Alloy Research Papers - Academia.edu (original) (raw)

Aluminum alloys have a high strength-to-weight ratio and proper anti-corrosion properties that are used in the automotive, shipbuilding and aerospace industries. The major problem with forming aluminum sheets is the low formability of aluminum sheets at room temperature. Therefore, in the present study, warm deep drawing (WDD) of AA5052-O aluminum alloy sheets with a thickness of 1mm was investigated at the different forming temperatures of 25, 80, 160, and 240°C (in the two isothermal and nonisothermal conditions) and punch speeds of 260, 560 and 1950 mm min-1 using experimental tests and finite elements simulation. The ﬁnite element simulation predictions show a good agreement with the experimental data. The results showed that an increase in forming temperature and a decrease in forming speed led to a decrease in forming force and an increase in cup height. Additionally, a microstructural and experimental investigation showed that the fracture of the cup corner radii occurs in th...

- by
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- Materials Science, Alloy, Deep Drawing

In the work, an elemental mixture of Ni and Ti was deposited by atmospheric plasma spray technology on the mild steel substrate by varying the process parameters such as primary gas flow rate and plasma arc current. The properties such as surface roughness, microhardness, and erosion rate of the coating were determined and the relationship between process parameters and coating properties was established. To optimize the process parameters and to find out the optimum parametric setting, the fuzzy technique for order preference by similarity to an ideal solution hybrid technique was im-plemented. By keeping all the parameters constant, the coating with better properties was obtained at an optimum parametric setting of 550 A arc current and 45 lpm primary gas flow rate. Furthermore, by implementing the Analysis of Variance, the primary gas flow rate was found to be a significant con-tributing factor. The X-ray diffraction analysis of the coating developed at an optimized parametric setting revealed Ni, Ti, NiTi-B2 phase, Ni3Ti, Ti2Ni, Ni4Ti3, TiO, and NiO phases. The bonding of the coating with the substrate was confirmed by the line scan energy dispersive spectroscopy analysis. The surface morphology of the eroded surface of the coating developed at the optimum parameter revealed the crater formation, chip formation, lip formation, plastic deformation, and groove formation mechanisms.

- by Ajit Behera
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- Surface Coatings, TOPSIS, Alloy, Parametric Optimization

Plastically deformed hand-filed Cu–Sn–5Zn ternary alloys with Sn concentrations 1, 2.5, and 5 wt % are investigated. Microstructural parameters are studied in terms of x-ray diffraction profile fitting analysis. It is observed by Dey et al. Acta. Mater. 53, 4635 2005 that the change in stacking fault probability with Sn concentration for ternary Cu–Sn–5Zn alloys is similar to Cu-based binary alloy Cu–Sn system but behaves in a different manner from Cu–1Sn–Zn ternary alloy systems. The crystallite size distribution is broader for alloy with 1 wt % Sn and becomes narrower with increasing Sn concentration. Value of dislocation density is of the order of 10 15 m −2 and shows a compositional dependence. Type of dislocation is found to be predominantly screw; 100-type dipoles may also be present in the cold-worked alloys. The dislocation arrangement is found to be more correlated in case of 1 wt % Sn compared to other alloys of higher Sn concentration. The stacking fault energy is obtained from modified Reed-Schramm equation and is of the order of 20 mJ m −2 with no significant compositional dependence.

- by Dr. Somenath Dey
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- Alloy

Four thousand eight hundred (4800) questionnaires targeted at establishing the frequency, causes and nature of injuries sustained in road accidents by commercial motorcycle operators within a period of five (5) years (2006 - 2010) were administered on operators, Motorcycle Hire Association (MOHA), Federal Road Safety Corps (FRSC) and the Transport Unit of the Nigerian Police Force in four major commercial towns of Benue State, Nigeria. Victims were also interviewed on nature of injuries sustained. Analysis of results revealed that, over speeding accounted for 22.9 % of accidents. Brake failure and non-compliant to traffic rules had 17.8 % respectively, followed by sudden stoppage by the law enforcement agent 15.4 %, recklessness 14.2 % and poor state of the road 11.8 %. Similarly, 38 %, 35 %, and 26 % of injuries recorded in Makurdi were fractures, bruises, and head injuries respectively. Oturkpo recorded 31 % bruises,
30 % fractures and 38 % head injuries. While Gboko recorded 24 % bruises, 22 % fractures and 53.8 % head injuries. ZakiBiam had 25 % bruises, 27 % fractures, and 46.9 % head
injuries. Conclusively Makurdi had 646 accidents, followed by
Oturkpo with 582, Gboko with 520 and Zaki-Biam with 330. These ranking can be justified by the population of the commercial towns. There is an urgent need to enforce the use of safety helmets and speed limits to reduce the number of accidents and the resulting injuries sustained by the users of this mode of transport. This paper also proposed a synergy of stakeholders aimed at manpower development of riders in line with the contemporary Science, Technology and Innovations (STI) policy on Nigeria.

- by kazeem Abubakar
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- Information, Mechanical properties, Magnesium, Copper

The following work gives an overview of lead importation in Augusta Raurica in the Roman period. For this, the lead isotope composition of 30 Roman lead objects (from the 1 st to the 4 th centuries A. D.) was compared with that of more than 2000 mines throughout Europe. The results show that, in the first and second centuries, lead was mostly imported from large centres of production in northern Germany and Great Britain. In the late Roman period, with the appearance of political tensions (Alaman raids, inflation, etc.), the lead seems to have been recycled. So far, evidence has been found in Augusta Raurica of local production from the Valais from the 1 st century A. D. onwards. But its role as producer of lead was only secondary.

- by Alex R. Furger
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- Archaeometallurgy, Copper, Silver, Iron

The paper presents the microstructure and corrosion behavior of an AlTiNiCuAgSn new equiatomic multicomponent alloy. The alloy was obtained using the vacuum arc remelting (VAR) technique in MRF-ABJ900 equipment. The microstructural analysis was performed by optical and scanning electron microscopy (SEM microscope, SEM-EDS) and the phase transformations were highlighted by dilatometric analysis and differential thermal analysis (DTA). The results show that the as-cast alloy microstructure is three-phase, with an average microhardness of 487 HV0.1/15. The obtained alloy could be included in the group of compositionally complex alloys (CCA). The corrosion resistance was studied using the potentiodynamic method in saline solution with 3.5% NaCl. Considering the high corrosion resistance, the obtained alloy can be used for surface coating applications.

- by Ionelia Voiculescu
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- Engineering, Materials Science, Microstructure, Materials

selective and sensitive spectrophotometric method has been proposed for the
determination of copper by forming red-brown chelate at pH 3.5 (3-4) with 2,3,4,6/-tetrahydroxy-3/-
sulfoazobenzene (THSA). Molar absorptivity of the complex having metal ligand ratio of 1:2 is 4.03
× 104 L mol−1 cm−1 at 485 nm. Its conditional stability constant (log K) is 7.98. The developed
method obeys Beer’s law for 0.032–1.905 μg mL−1 Cu(II). Group 1A elements, group 2A elements,
rare earth elements, group 7A elements, phosphates, ascorbic acid and cations do not interfere
copper determination. The proposed method is rapid and simple, and it can be easily applied on
certificated alloys and pharmaceutical formulations for determining copper.

- by Ülkü Dilek Uysal
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- Copper, Pharmaceutical, Alloy, Determination

The application of aluminium alloys in automotive body structure is one of the main developments in recent years. The increase of the mechanical properties of the ductile die-casting is one of the most critical topics for the application. In this work, the effect of melt superheating on the morphology, size and distribution of α-Al phase and Fe-rich intermetallics, and on the mechanical properties of the Al-Mg-Si-Mn diecast alloy was investigated. The results showed that the refined microstructure could be obtained through melt superheating. The volume fraction of dendritic α-Al phase and the Fe-rich intermetallic phase formed in the shot sleeve was significantly reduced, resulting in the refined microstructure. Overall, the melt superheating could improve the mechanical properties of the yield strength, ultimate tensile strength, and elongation of the diecast Al-Mg-Si-Mn alloy. And, the Fe-rich intermetallic phase formed in the shot sleeve with the coarse compact morphology and formed in the die cavity with the fine compact particles were identified as the same α-Al12(Fe,Mn)3Si composition in the present experimental conditions, which was not affected by the melt superheating.

- by xinliang yang and +1
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- Materials Science, Microstructure, Mechanical properties, Solidification

In this paper we present a short synthesis about iron, lead, copper and silver metallurgical activities in the Southern Meseta. At present, analytical researches in this area are quite scarce and there are little data from metallurgical workshops. More detailed information has been obtained about the pattern of alloys in copper-based metals since the 2nd Iron Age,
standing out the relevant presence of leaded bronze objects (approximately 30%). The first lead isotopes analyses from this region have been already published.

- by Ignacio Montero Ruiz
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- Archaeometallurgy, Copper, Silver, Iron

—The proposed article describes a compressor design for using the heat generated in the hydrogen absorption process into the metal alloy during compression. The absorption of hydrogen into the alloy occurs after the desired pressure has been achieved, whereby the catalytic effect of the used metals to dissociate the hydrogen molecule and the subsequent diffusion of the hydrogen atoms into the intermetallic space of the lattice occur. The absorption process is accompanied by a gradual increase in pressure up to the total saturation value of the metal. The equilibrium pressure at which the absorption occurs is highly dependent on the temperature of the alloy. The difference in the equilibrium pressures of MH materials at an acceptable temperature change has led to efforts of creating a hydrogen compressor that would use MH heating and refrigeration heat cycle.

- by Engineering Journal Publication of Research work
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- Engineering, Hydrogen, Research, Compressor

Service Oriented Architecture (SOA) is one of the most popular concepts to implement different systems. However it faces many challenges in terms of security. As a result, a number of standard and frame works are formed as supporters. The main purpose of this survey is to create a model for a secure Service-oriented Architecture (SOA) based on a formal model specified in the Alloy modeling language. The proposed model is based on the basic SOA as well as CIA and include secure identities, secure interaction, secure publish and secure discover. To validate that our model is secure, we created an Alloy model for security. We create predicates that model our security definitions and the obstacles which violate these security definitions. Then we use each security definition against the obstacle that violates it to define secure elements in our model.

- by ACSIJ Journal
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- Authentication, SOA, Alloy, Non-Repudiation
- by Jien-wei Yeh
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- Engineering, Materials Engineering, Materials Science, High Entropy Alloys

Zr-2.5 Nballoy is used as a pressure tube material in pressurized heavy water reactor (PHWR). It is one of the most critical component which decides the lifespan of the reactor. The in-reactor degrading phenomenon of prime concern is dimensional changes caused by irradiation induced creep and growth processes. The present study aims to understand the mechanism of irradiation damage by irradiating the alloy with heavy ion. Such type of irradiation study would facilitate larger damage of material in a shorter time. Zr-2.5Nb alloy samples were irradiated using 315 keV Ar9+ ion for different durations. The irradiation doses were varied in the range of 3.1X1015 to 4.17X1016 Ar9+/cm2. SRIM calculation was carried out to evaluate damage profile in the irradiated samples. Beam based Positron Annihilation Spectroscopy (PAS) technique was used for depth profiling to characterize defect distribution in the alloys. The no. of defects generated is seen to increase with the increase in the fluence.

- by aruna devi
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- Engineering, Physics, Materials Science, Physical sciences

A study has been conducted of the influence of the surface finish on the behaviour against the corrosion of samples of alloy AA 5083 immersed in aerated solutions of NaCl at 3.5%. Samples polished from 80 to 1200 grit have been tested, utilising as experimental techniques, measurements of weight loss, optical and scanning electron microscopy, linear polarisations and electrochemical noise measurement (ENM). In the conditions studied, the principal corrosion process that takes place is localised alkaline corrosion (LAC). This type of corrosion occurs as a consequence of the alkalinisation of the area surrounding the Al(Mn,Fe,Cr) cathodic precipitates that exist in the alloy. The results obtained indicate that the samples polished to 1200 grit present a greater susceptibility to processes of localised alkaline corrosion than the samples polished to 80 grit. It has been found that the degree of polishing conditions the number of intermetallic particles exposed. Hence the differences of behaviour observed between the sets of results obtained have been interpreted as an effect function of the density of cathodic intermetallic particles exposed on the surface.

A new a biocompatible Ti 42 Zr 40 Ta 3 Si 15 (atomic %) porous bulk glassy alloy was produced by combination of rapid solidification and powder metallurgy techniques. Amorphous alloy ribbons were fabricated by melt spinning, i.e. extremely fast quenching the molten alloy with 10 6 K/s from T = 1973 K down to room temperature. The ribbons were then cryo-milled at liquid nitrogen temperature in order to produce powder, which was subsequently hot pressed. The resulting thick pellets have a porosity of about 14 vol%, a high compression strength of 337 MPa and a Young's modulus of about E = 52 GPa, values very close to those characteristic of cortical bone. Moreover, the morphology of the samples is very similar to that of cortical bone. The biocompatibility, which is due to the absence of any toxic element in the chemical composition, together with the suitable mechanical behavior, make these samples promising for orthopedic and dentistry applications. Statement of Significance Ti-based alloys are nowadays the standard solution for biomedical implants. However, both the conventional crystalline and amorphous alloys have higher rigidity as the human bone, leading to the damage of the bone at the interface, and contains harmful elements like vanadium, aluminum, nickel or beryllium. The hierarchical porous structures based on glassy alloys with biocompatible elements is a much better alternative. This work presents for the first time the manufacturing of such porous bodies starting from Ti-based amorphous alloy ribbons, which contains only non-harmful elements. The morphology and the compressive mechanical properties of these new products are analyzed in regard with those characteristic to the cortical bone.

- by A. Raduta
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- Materials Science, Biomaterials, Multidisciplinary, Porous Materials

Abstract This study investigates the effect of adding 0.5 wt% ZnO nanoparticles into Sn–5 wt% Sb–0.5 wt% Cu (SSC505) solder alloy on the growth of intermetallic compounds (IMCs) as well as the associated changes of microstructure. It was found that, the morphologies of the IMCs transformed to refinement forms due to the adsorption effect of ZnO nanoparticles. Systematic study of tensile properties was performed for bulk solders over a wide range of strain rates at various temperatures to determine the plastic deformation mechanism. Obviously, the ultimate tensile strength (UTS) and the yield stress ( σ y ) were improved. This can be attributed to reinforcement of ZnO nanoparticles, refined β-Sn grains and IMCs that could obstruct the dislocation slipping. The obtained results are consistent with the prediction of the classic theory of dispersion strengthening. Furthermore, the average activation energy ( Q ) for plain and composite solders were 57 and 59 kJ/mol, respectively, which close to that of pipe-diffusion mechanism in Sn based solder matrix.

- by Eid Elsayed
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- Materials Engineering, Mechanical Engineering, Materials Science, Microstructure

The interaction of the physiological medium and living tissues with the implant surfaces in biological environments is regulated by biopotentials that induce changes in the chemical composition, structure and thickness of the oxide film. In this work, oxide films grown on CoCr alloys at 0.5 V vs Ag/AgCl and 0.7 V vs Ag/AgCl have been characterized through overall and localized electrochemical techniques in a phosphate buffer solution and 0.3% hyaluronic acid. Nanopores of 10-50nm diameter are homogeneously distributed along the surface in the oxide film formed at 0.7 V vs Ag/AgCl. The distribution of the Constant Phase Element studied by local electrochemical impedance spectroscopy showed a three-dimensional (3D) model on the oxide films grown at 0.5 V vs Ag/AgCl and 0.7 V vs Ag/AgCl. This behaviour is especially noticeable in oxide films grown at 0.7 V vs Ag/AgCl, probably due to surface inhomogeneities, and resistive properties generated by the potentiostatic growth of the oxide f...

A variety of seemingly unrelated processes, such as core-mantle interaction, desulfurization, and direct precipitation from a silicate melt have been proposed to explain the formation of Ru-Os-Ir alloys (here referred to as osmiridiums) found in terrestrial mantle rocks. However, no consensus has yet been reached on how these important micrometer-sized phases form. In this paper we report the results of an experimental study on the solubilities of Ru, Os and Ir in sulfide melts (or mattes) as a function of alloy composition at 1300°C. Considering the low solubilities of Ru, Os, and Ir in silicate melts, coupled with their high matte/silicate-melt partition coefficients, our results indicate that these elements concentrate initially at the ppm level in a matte phase in the mantle source region. During partial melting, the extraction of sulfur into silicate melt leads to a decrease in fS 2 that triggers the exsolution of osmiridiums from the refractory matte in the residue. The newly formed osmiridiums may persist in the terrestrial mantle for periods exceeding billions of years.

- by Klaus Jochum
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- Geology, Geochemistry, PGE, Genesis

The antibiofouling ability of three hybrid sol-gel coatings against P. aeruginosa for the protection of AA2024-T3 aluminium alloy has been investigated. The polymers were synthesized by mixing tetraethoxysilane (TEOS) with three precursors: (a) triethoxypropylsilane (TEPRS), (b) triethoxypentylsilane (TEPES) and (c) triethoxyoctylsilane (TEOCS). The main difference between the three precursors is the length of the aliphatic chain of one of the substituents. The antibacterial properties of the polymers were examined using viability techniques. The morphology of the polymers was characterized using scanning electron microscopy (SEM). The resistance of the AA2024 alloy coated with the respective polymers to microbiologically influenced corrosion was evaluated by potentiodynamic polarization. The results showed that the polymers possess antibacterial ability against P. aeruginosa and that the length of the aliphatic chain of the precursors does not significantly affect this property. Further, the electrochemical measurements revealed that the coatings inhibited microbiologically influenced corrosion in the mixture of P. aeruginosa and 0.1 M NaCl, due to the antibacterial properties of the polymers. A correlation between the degree of protection and the length of the aliphatic chain was revealed. Thus, the longer the chain length, the greater the protective effect. The antibiofouling ability resides mainly on the hydrophobic characteristic of polymers and the pH change occurring at the polymer-electrolyte interface when the coated aluminium alloy was immersed in the electrolytes.

- by nelson vejar
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- Microbiology, Materials Science, Chemistry, Nanotechnology

The starting microstructure of a dispersion fuel plate will impact the overall performance of the plate during irradiation. To improve the understanding of the as-fabricated microstructures of U-Mo dispersion fuel plates, particularly the interaction layers that can form between the fuel particles and the matrix, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses have been performed on samples from depleted U-7Mo (U-7Mo) dispersion fuel plates with either Al-2 wt.% Si(Al-2Si) or AA4043 alloy matrix. It was observed that in the thick interaction layers, U(Al, Si)3 and U6Mo4Al43 were present, and in the thin interaction layers, (U, Mo) (Al, Si)3, U(Al, Si)4, U3Si3Al2, U3Si5, and possibly USi-type phases were observed. The U3Si3Al2 phase contained some Mo. Based on the results of this investigation, the time that a dispersion fuel plate is exposed to a relatively high temperature during fabrication will impact the nature of the interaction layers around the fuel particles. Uniformly thin, Si-rich layers will develop around the U-7Mo particles for shorter exposure times, and thicker, Si-depleted layers will develop for the longer exposure times.

Brazing of titanium provides a joining technique suitable for the fabrication of highly-loaded aerospace components, but it still poses numerous challenges, such as the formation of brittle intermetallic interphases. This study of the interphase formation in brazed joints consisting of different titanium alloys (Ti-CP2, Ti-CP4, Ti-6Al-4V, Ti-6Al-2Mo-4Zr-2Sn) and Ag28Cu shows that complex reactions lead to the formation of various intermetallic phases including a Ti2Cu-TiCu boundary zone. The compositions of the titanium alloys influenced the particular microstructures, which have been characterized with various methods including synchrotron X-ray microtomography. Tensile tests evidence high ultimate tensile strengths that are, importantly, not directly limited by the strength of the brazing alloy. The strength of the Ti2Cu-TiCu phase boundary is significantly increased by the alloying elements in Ti-6Al-4V and Ti-6Al-2Mo-4Zr-2Sn and the crack paths change from boundary failure to tr...

- by Galina Kasperovich
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- Materials Science, Open Access, Metallurgy, Brazing

Aluminium (Al) alloys are employed, from aerospace, automotive body panel, building industry to kitchen wares. This paper attempts to close an existing gap in the usage and variation in the percentage weight (% w.t.) of two constituents [Magnesium (Mg) and Copper (Cu)] in Al alloy and evaluate the impact of such variations on yield strength in N/mm2 and percentage elongation (% e) at ambient temperature. Experimental X7475 alloy was prepared from constituents drawn from 6 % Zn, 2.5 % - 3.5 % Mg, 1.8 % - 3.0 % Cu, 0.03 % Mn, 0.23 % Cr and Al as balance in all cases. The result revealed that yield strength increased with increase in Mg and decreased with increase in Cu as a maximum yield strength of 384.57 N/mm2 was displayed by an alloy of 2.5 % Mg, 3.0 % Cu while the least yield strength of 130.00 N/mm2 was recorded by an alloy of 3.5 % Mg, 3.0 % Cu. Ductility (% e) increased with increase in Cu. The paper submitted that mechanical properties of Al alloys depend not only on the content of alloying elements, but also on their relative chemistries with each other, impact of impurities and heat treatments.

- by kazeem Abubakar
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- Information, Mechanical properties, Magnesium, Copper

Molybdenum and its alloys are potential materials for high-temperature applications. However, molybdenum is susceptible to embrittlement because of oxygen segregation at the grain boundaries. In order to alleviate the embrittlement small amounts of zirconium were alloyed to a solid solution of Mo-1.5Si alloy. Two Mo-based alloys, namely Mo-1.5Si and Mo-1.5Si-1Zr, were investigated by the complementary high-resolution methods transmission electron microscopy and atom probe tomography. The Mo-1.5Si alloy shows a polycrystalline structure with two silicon-rich intermetallic phases Mo(5)Si(3) and Mo(3)Si located at the grain boundaries and within the grains. In addition, small clusters with up to 10 at% Si were found within the molybdenum solid solution. Addition of a small amount of zirconium to Mo-1.5Si leads to the formation of two intermetallic phases Mo(2)Zr and MoZr(2), which are located at the grain boundaries as well as within the interior of the grain. Transmission electron microscopy shows that small spherical Mo-Zr-rich precipitates (<10nm) decorate the grain boundaries. The stoichiometry of the small precipitates was identified as Mo(2)Zr by atom probe tomography. No Si-enriched small precipitates were detected in the Mo-1.5Si-1Zr alloy. It is concluded that the presence of zirconium hinders their formation.

This research focused on the investigation of the metallurgical behavior of the Al0.8CoCrFeNi high-entropy alloy and S235JR structural steel, welded with (Ni, Fe)-rich filler metal, by the Gas Tungsten Arc Welding (GTAW) method. The electric arc and the welding pool were protected against the contamination with gases from the environment, by employing high-purity Ar 4.8 inert gas that plays an important role in reducing the oxidation effects and the development of cracks in the weld and the adjacent areas. The microstructure and microhardness analysis did not reveal the existence of fragile phases, cracks, inadequate penetration, or other imperfections, showing an appropriate adhesion between the deposited metal and the substrates. At the interface between the Ni-rich weld metal and the high-entropy alloy, a higher hardness (448 HV0.2) than in the base material (358 HV0.2) was measured. Energy-dispersive X-ray analysis (EDS), performed at the interface between the weld metal and the...

- by Ionelia Voiculescu
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- Materials Science, Microstructure, Metallurgy, Welding

High Entropy Alloys are a class of alloys which have been shown to largely exhibit stable microstructures, as well as frequently good mechanical properties, particularly when manufactured by additive manufacturing. Due to the large number of potential compositions that their multi-component nature introduces, high throughput alloy development methods are desirable to speed up the investigation of novel alloys. Here, we explore once such method, in-situ alloying during Additive Manufacture, where a powder of a certain pre-alloyed composition is mixed with the required composition of powder of an additional element, such that alloying takes place when powders are melted during the process. To test the effectiveness and capability of the approach, selective laser melting has been used to manufacture pre-alloyed CoCrFeNi, and also CoCrFeNiCu and CoCrFeNiTi alloys by combining pre-alloyed CoCrFeNi powder with elemental powders of Cu and Ti. Processing parameter variations are used to fin...

- by Russell Goodall
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- Materials Science, Microstructure, Metallurgy, High Entropy Alloys
- by Frank C Walsh
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- Materials Engineering, Condensed Matter Physics, Materials Science, Microstructure
- by Audrey Fasching
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- Materials Engineering, Materials Science, Medical Device, Nickel

ABSTRACT The effect of pre-straining of 1%, 3%, 5%, and 7% on fatigue life of 7050-T7451 aluminium alloy has been evaluated. Using dogbone unnotched flat specimens, axial fatigue tests were conducted under a constant amplitude sinusoidal wave loading at stress ratio of 0.1 in air at room temperature. The results demonstrate a tendency of fatigue life reduction with the pre-straining level. Optical microscopy analysis revealed that the pre-straining anticipates some microstructural changes occurring during fatigue testing, such as slipped grains and persistent slip bands (PSBs) formation, which are commonly related to fatigue life reduction. However, heterogeneities observed in the material make this reduction less prominent. Statistical analysis using a bootstrap method suggests also a reduction in fatigue life with increasing the pre-strain level.

- by joud joud
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- Materials Engineering, Mechanical Engineering, Materials Science, Statistical Analysis

Precipitation in Fe-Cr-Ni-Al-(Cu) model alloys was investigated after ageing for 0.25, 3, 10 and 100 h at 798 K. Characterization of nanoscale precipitates was performed using three-dimensional atom probe microscopy and transmission electron microscopy. The precipitates are found to be enriched in Ni and Al (Cu) and depleted in Fe and Cr. After 0.25 h of ageing the number density of precipitates is $8 Â 10 24 m À3 , their volume fraction is about 15.5% and they are near-spherical with an average diameter of about 2-3 nm. During further ageing the precipitates in the both alloys grow, but the coarsening behaviour is different for both alloys. The precipitates of the Cu-free alloy grow much faster compared with the Cu-containing alloy and their density decreases. Precipitates in Cu-free alloy change to plate shaped even after 10 h of ageing, whereas those of Cu-containing alloy remain spherical up to 10 h of ageing. The influence of Cu addition on precipitation in these model alloys is discussed with respect to the different coarsening mechanisms.

- by N. Wanderka
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- Materials Science, Chemistry, Medicine, Ultramicroscopy

The mechanical properties of age hardenable Al alloys depend strongly on the precipitate microstructure. This work has investigated the relationship between properties such as strength and ductility and the distribution of precipitates, using three Al-Mg-Si(-Cu) alloys (Cu≲0.1 at.%). A range of ageing conditions was examined in order to understand the effect of an evolving precipitate microstructure, and the results were used as input for strengthening models. The mechanical properties were obtained by tensile tests and microstructure characterisation was attained by transmission electron microscopy. The results showed that minor changes to the Si, Mg, and Cu additionsthe total addition (at.%) kept approximately equalhad a significant impact on material properties, with corresponding changes in the precipitate microstructure. On the peak strength plateaus differences as large as 35 MPa in yield strength were measured between the strongest and the weakest alloy, obtained as 410 MPa and 375 MPa, respectively. Higher material yield strength correlated well with a refined precipitate microstructure comprising higher number densities of smaller precipitates. Differences with respect to material ductility first appeared after moderate overageing of the alloys, showing negative correlation with material strength. At significantly overaged conditions the differences in strength exceeded 100 MPa, demonstrating large differences with respect to the thermal stability of these materials, which has important consequences for alloys exposed to elevated temperatures under in-service conditions. The highly comprehensive body of data presented here should serve as a valuable reference in the development of precipitation and strengthening models for the Al-Mg-Si-Cu system and will hopefully incite further investigations on the topics covered.

- by Bjørn Holmedal
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- Materials Engineering, Mechanical Engineering, Materials Science, Microstructure
- by Frank Goodwin
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- Materials Science, Design, Metallurgy, Experimental Design

In this study, nanostructured biodegradable pure Zn, Zn-4 wt. % Mn and Zn-24 wt. % Mn alloys were produced by 20 h mechanical alloying and consequent cold pressing and sintering. Structural evolutions were investigated using the X-ray diffraction technique. Also, the microstructure was characterized by scanning electron microscopy. The effects of alloy composition on density, mechanical properties, corrosion behavior in Hank's solution, cell viability and cell attachment were investigated. Crystallite size of the synthesized alloys after 20 h of milling reached to less than 40 nm and remained less than 80 nm after consolidation and sintering for 1 h. Alloys contain MnZn 13 as second phase which affect mechanical and corrosion properties. Compressive yield strength of Zn, Zn-4Mn and Zn-24Mn alloys reached from 33 to 290 and 132 MPa and corrosion rate of Zn-4Mn tailored to 0.72 mm/yr. Cell viability and cell attachment show biocompatibility of these alloys. Results demonstrate that Zn-Mn alloy can be a new suitable biodegradable candidate.

Amaç: Bu çalışmanın amacı ortodontik tedavi görmemiş, Sınıf I oklüzyon gösteren ve ortodontik tedavi geçmişi olmayan Türk bireylerden oluşan bir örneklem grubundan elde edilen mandibular ark boyutları ile farklı üretici firmalar tarafından üretilen ark tellerinin boyutları arasındaki uyumun değerlendirilmesidir. Gereç ve Yöntemler: Bu araştırma kapsamında iskeletsel ve dental Sınıf I ilişkiye sahip, minimal çapraşıklığı bulunan toplam 40 bireyden mandibular alçı model elde edilmiştir. Ortodontik modeller fotokopi makinesi aracılığı ile iki boyuta indirgenmiş, interkanin mesafe, kanin derinliği, intermolar mesafe ve molar derinliği kaydedilmiştir. Aynı parametreler 5 üretici firma tarafından pazarlanan dikdörtgen kesitli 8 ark telinde (A'dan H'ye kadar isimlendirilmiş) de ölçülerek aradaki fark karşılaştırılmıştır.

- by kübra yaradanakul
- •
- Materials Science, Metallurgy, Arch, TURKISH

In the present investigation, electrochemical corrosion techniques (cyclic potentiodynamic and potentiostatic) were used to study the localized corrosion (pitting/crevice) behaviour of a a cobalt-base alloy, Stellite-6. This alloy was produced by two different powder metallurgy (P/M) processing routes, namely, hot isostatic pressing (HIP) and wet powder pouring (WPP). The behaviour of the wrought alloy was also investigated for comparison. Corrosion tests were performed in neutral 3 % NaCl solution at ambient temperature. The results showed that the HIP material possessed the highest resistance to localized corrosion. This was explained in relation to the processing parameters and the microstructure of the alloy. The results of runs conducted in neutral test solutions showed that the critical crevice temperature. CCT, is certainly above the test temperature (room temperature). However, lowering the test solution pH (to 3 and 1.5) led to the onset of crevice corrosion. It was clear t...

- by Ahmed Nassef
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- Nuclear Engineering, Materials Science, Metallurgy, Corrosion Engineering
- by Romy Romantiko
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- Materials Science, Microstructure, Metallurgy, Composite Material

An evaluation of aluminium alloy for plasticity applications was undertaken to bridge the gap in appraising the impact of variation of alloying elements such as magnesium (Mg) and copper (Cu) on plasticity as a mechanical property of the aluminium alloy. To this end, twenty seven (27) samples of aluminium alloys were produced with constituents drawn from 6 % zinc (Zn), 2.5 % - 3.5 % magnesium (Mg), 1.8 % - 3.0 % copper (Cu), 0.03 % manganese (Mn), 0.23 % chromium (Cr) and aluminium (Al) as balance in all cases. 0.1 gram of sulphur (S), which the same as the quantity of iron (Fe) in chromium (Cr) and manganese (Mn), was added to oxidize (eradicate) iron (Fe). Samples were subjected to hardness test; to measure the ability of the alloy to resist plastic deformation and percentage elongation (% e) to unveil the mechanical properties of the alloy. Maximum Vickers hardness (Hv) of 130.7 was displayed by an alloy of 6 % zinc (Zn), 2.5 % magnesium (Mg), 1.8 % copper (Cu), 0.03 % manganese ...

- by kazeem Abubakar
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- Engineering, Electronic Engineering, Mechanical Engineering, Chemical Engineering

Aluminium (Al) alloys are employed, from aerospace, automotive body panel, building industry to kitchen wares. This paper attempts to close an existing gap in the usage and variation in the percentage weight (% w.t.) of two constituents [Magnesium (Mg) and Copper (Cu)] in Al alloy and evaluate the impact of such variations on yield strength in N/mm 2 and percentage elongation (% e) at ambient temperature. Experimental X7475 alloy was prepared from constituents drawn from 6 % Zn, 2.5 %-3.5 % Mg, 1.8 %-3.0 % Cu, 0.03 % Mn, 0.23 % Cr and Al as balance in all cases. The result revealed that yield strength increased with increase in Mg and decreased with increase in Cu as a maximum yield strength of 384.57 N/mm 2 was displayed by an alloy of 2.5 % Mg, 3.0 % Cu while the least yield strength of 130.00 N/mm 2 was recorded by an alloy of 3.5 % Mg, 3.0 % Cu. Ductility (% e) increased with increase in Cu. The paper submitted that mechanical properties of Al alloys depend not only on the content of alloying elements, but also on their relative chemistries with each other, impact of impurities and heat treatments.

- by kazeem Abubakar
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- Materials Science, Metallurgy, Materials Science and Engineering, Information

The present work aims to study the tribological behavior of an extruded ZK60 alloy in the presence of Ce; in a previous study, among ZK60 alloys with different Ce addition rates, an alloy with 3 wt% of Ce was found to exhibit the most promising mechanical (e.g., hardness and strengths) properties, while its wear behavior remained unknown. The results of microstructural examinations by optical and electron microscopes show that Ce addition reduces the grain size from 6.1 to 2.0 μm. Besides, in addition to the precipitates already distributed in the base alloy (Mg7Zn3), Ce could promote the formation of a new precipitate (MgZn2Ce), increasing the total fraction of the precipitates. These microstructural evolutions enhance the strengths of the studied ZK60 alloy, as the yield and tensile strengths increase from 212 to 308 MPa and from 297 to 354 MPa, respectively. A pin on disc tribometer was employed to study the wear behavior of the developed alloy under different normal loads (5, 20...

- by Masih Banijamali
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- Materials Engineering, Materials Science, Microstructure, Metallurgy
- by John Olawale
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- Materials Engineering, Genetics, Materials Science, Metallurgy

Two new alloy compositions for possible disk rotor applications have been examined. Both were intended to have higher γʹ content than the existing alloy, RR lO00, and be produced using powder metallurgy and isothermal forging to enable forgings to show a consistent coarse grain microstructure. Small pancake forgings of the new alloys and RRlO00 were made and from these, blanks were cut, solution heat treated, cooled at measured rates and aged. Results of screening tests to understand the tensile, creep and dwell crack growth behavior, oxidation resistance and phase stability of these new alloys and coarse grain RRlO00 are reported. The development alloys were similar in composition but exhibited different tensile and creep properties, phase stability and resistance to oxidation damage. Despite attempts to minimize variation in microstructure from heat treatment, differ ences in γʹ size distribution were found to influence tensile and creep behavior. One of the new alloys (Alloy 2) showed improved yield and tensile strength compared to RRlO00. Alloy 2 displayed similar initial creep strain behavior to RRl000 but superior resistance to subsequent creep damage , producing longer creep rupture lives. All of the alloys showed crack retardation at low stress intensity factor ranges (LlK) from 3600 s dwell cycles at 700 °C in air. This occurred whilst crack growth was intergranular. Alloy 1 was found to precipitate C14 Laves phase from long term exposure at 800 °C. Like RRlO00, CT phase was not detected in the new alloys after 750 h at 800 °C.

- by Hangyue Li
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- Materials Science, Superalloys, Alloy

Hypo-eutectic Ti-6.5 wt% Si alloy modified by separate additions of misch metal and low surface tension elements (Na, Sr, Se and Bi) has been examined by microscopic study and thermal analysis. Addition of third element led to modification of microstructure with apparently no significant enhancement of tensile ductility, with the exception of bismuth. Bismuth enhanced the ductility of the alloy by a factor of two and elastic-plastic fracture toughness to 9 MPa m-1/2 from a value of almost zero. The improved ductility of bismuth modified alloy is attributed to the reduced interconnectivity of the eutectic silicide, absence of significant silicide precipitation in the eutectic region and increase in the volume fraction of uniformly distributed dendrites. These changes are accompanied by a decrease in the temperature of eutectic solidification.

- by Kallarackel Jacob
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- Engineering, Materials Science, Microstructure, Alloy

Abstract The composition, microstructure and corrosion behavior of Al Mg Ga In Sn alloy in cast and heat-treatment were investigated by XRD (X-ray diffraction), SEM (scanning electron microscope) and EDS (energy dispersive spectrometer). The hydrogen evolution parameters, and the electrochemical properties based on different heat-treatment parameters conditions and immersion temperature were also tested. As the heat-treated temperature increased, the second phases were found to be spheroidizing or ellipsoidal shape due to the diffusion and solid solution. The reaction can be divided into three stages: i) the amalgamation initial stage; ii) the micro-galvanic reaction for propagation corrosion; iii) the dissolution-precipitation reaction for uniform corrosion. The hydrolysis rate reached the maximum value when the sample was annealed at temperature of 500 °C for 9 h. The hydrogen generation rate and the open electrochemical potential of the activated aluminum under water are both depending on heat treatment time, heat treatment temperature, and reaction temperature. A corrosion mechanism was also proposed in which Mg2Sn and eutectic phase acted as the induction reaction stage during hydrolysis reaction.

- by Yongni Gou
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- Engineering, Materials Science, Hydrogen, Hydrogen Energy
- by Irakli Paghava
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- History of Georgia, Alloy, Medieval Georgia, Georgian Numismatics

Fe-26Si-9B alloy was selected as a potential phase change material (PCM) to store energy at temperatures up to 1300 °C. A suitable refractory material is crucial to building a PCM container for Fe-26Si-9B alloy in thermal energy storage systems. The refractory material should have the ability to withstand corrosion from liquid Fe-26Si-9B alloy and should not pollute the alloy after long-term thermal cycles at high temperatures. In this work, Si3N4 was selected as a candidate refractory material. To investigate the interaction between Si3N4 and Fe-26Si-9B alloy, the wettability property of an Fe-26Si-9B/Si3N4 system was examined in a sessile drop furnace at temperatures up to 1350 °C. Moreover, Fe-26Si-9B alloy was subjected to 1–12 thermal cycles at temperatures between 1100 and 1300 °C, where the alloys were placed in Si3N4 crucibles in a resistance furnace under argon. According to the experiments, the equilibrium contact angle between the Fe-26Si-9B droplet and Si3N4 substrate wa...

- by Merete Tangstad
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- Materials Science, Metallurgy, Crystals, Wetting

Nanoparticles (NPs) of noble metals, namely gold and silver, remain promising anticancer agents capable of enhancing current surgery-and chemotherapeutic-based approaches in cancer treatment. Bimetallic AgAu composition can be used as a more effective agent due to the synergetic effect. Among the physicochemical parameters affecting gold and silver nanoparticle biological activity, a primary concern relates to their size, shape, composition, charge, etc. However, the impact of metal components/composition as well as metal topological distribution within NPs is incompletely characterized and remains to be further elucidated and clarified. In the present work, we tested a series of colloidal solutions of AgAu NPs of alloy and core-shell type for an antitumor activity depending on metal molar ratios (Ag:Au = 1:1; 1:3; 3:1) and topological distribution of gold and silver within NPs (Au core Ag shell ; Ag core Au shell). The efficacy at which an administration of the gold and silver NPs inhibits mouse Lewis lung carcinoma (LLC) growth in vivo was compared. The data suggest that in vivo antitumor activity of the studied NPs strongly depends on gold and silver interaction arising from their ordered topological distribution. NPs with Ag core covered by Au shell were the most effective among the NPs tested towards LLC tumor growth and metastasizing inhibition. Our data show that among the NPs tested in this study, Ag core Au shell NPs may serve as a suitable anticancerous prototype.

- by Anna M Eremenko
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- Materials Engineering, Condensed Matter Physics, Materials Science, Nanoparticle

Aluminium-nickel alloy with nominal composition 6.5 wt.% Ni has been manufactured by chill-casting and melt-spinning methods. The resulting microstructures have been examined by optical microscopy (OM) and scanning electron microscopy (SEM). These results showed that the microstructure of the rapidly solidified ribbons is clearly different from that of the chill-casting alloy. The effect of the wheel speed on rapidly solidified ribbons dimension and the relationship between ribbon thickness and wheel speed was also examined. It was found that there is good relationship between ribbon thickness and wheel speed. The ribbon thickness decreased inversely with the wheel speed. Furthermore, the microhardness of the chill-casting alloy and the rapidly solidified ribbons were measured by using a Vickers indenter. The result showed that the microhardness of the rapidly solidified ribbons is higher than that of chill-casting alloy.

- by Musa Göğebakan
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- Materials Engineering, Mechanical Engineering, Materials Science, Metallurgy
- by Martín A. Rodríguez
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- Materials Science, Electrochemistry, Corrosion, Alloy