Aluminium Alloy Development Research Papers (original) (raw)

The electrochemical properties of high strength 7xxx aluminium alloys strongly depend on the substitutional occupancy of Zn by Cu and Al in the strengthening η-phase with the two-sublattice structure, and its microstructural and compositional prediction is the key to design of new generation corrosion resistant alloys. In this work, we have developed a chemical-potential-based phase-field model capable of describing multi-component and two-sublattice ordered phases, during commercial multi-stage artificial ageing treatments, by directly incorporating the compound energy CALPHAD formalism. The model developed has been employed to explore the complex compositional pathway for the formation of the η-phase in Al-Zn-Mg-Cu alloys during heat treatments. In particular, the influence of alloy composition, solute diffusivity, and heat treatment parameters on the microstructural and compositional evolution of η-phase precipitates, was systematically investigated from a thermodynamic and kinetic perspective and compared to electron probe microanalysis validation data. The simulated η-phase growth kinetics and the matrix residual solute evolution in the AA7050 alloy indicates that Zn depletion mainly controlled the η-phase growth process during the early stage of ageing, resulting in fast η-phase growth kinetics, enrichment of Zn in the η-phase, and an excess in residual Cu in the matrix. The gradual substitution of Zn by Cu atoms in the η-phase during the later ageing stage was in principle a kinetically controlled process, owing to the slower diffusivity of Cu relative to Zn in the matrix. It was also found that the higher nominal Zn content in alloys like the AA7085 alloy, compared to the AA7050 alloy, could significantly enhance the chemical potential of Zn, but this had a minor influence on Cu, which essentially led to the higher Zn content (and consequently lower Cu) seen in the η-phase. Finally, substantial depletion of Zn and supersaturation of Cu in the matrix of the AA7050 alloy was predicted after 24 h ageing at 120 • C , whereas the second higher-temperature ageing stage at 180 • C markedly enhanced the diffusion of Cu from the supersaturated matrix into the η-phase, while the matrix residual Zn content was only slightly affected.

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- Computational Materials Science, Modeling, Heat treatment of metals and alloys, Simulation

Guinea holds a third of the world's bauxite reserves, tops the list with about 7.4 billion Metric tons (MT) and mines only 7% of the world total, being the biggest exporter. Ghana's reserve is approximately 160 million MT with traces in Mozambique and Nigeria. Australia, second to Guinea in reserve, and China top the world production chart with the former producing about 31% and the latter about 16%. This is an indication that African countries lack the critical inputs necessary to derive the competitive beneficiation of the Aluminium industry, hence the low downstream value addition observed on the continent. Aluminium and its alloys find application in aerospace, automotive, building and kitchen utensil industries. This light metal may drastically change the landscape of energy demand of automobile industry before 2040 with about 187 kg lighter than the steel electric vehicle and demand up 13 percent in 2017. A promising X7475 alloy (Al-Zinc group) has the potentials to change the account of Aluminium Industry in Africa if well harnessed. This study fully appreciated data from the monthly Primary Aluminium Production of International Aluminium Institute (IAI). Data were processed in Microsoft Excel and used to peddle X7475 alloy as an option for African countries to explore. The study suggests that African countries should collaborate with governments, Industries, Financial Institutes and Academics to develop homegrown aluminium alloys targeted at closing the demand gap created by the electric vehicles (EVs) industry and beyond.

- by kazeem Abubakar
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- Aluminium Alloys, Aluminium Alloy Development, Aluminium Industry, Aluminium

In this study, the effect of Sc addition on the grain reﬁnement, modiﬁcation of the eutectic Si, mechanical and wear properties of A356 and A356–10 wt% TiB2 in situ composite has been investigated. The A356– 10 wt% TiB2 composites were prepared by an in situ reaction between K2TiF6 and KBF4 salts, which are added in proper stoichiometric ratio to form TiB2 in the A356 alloy melt at a temperature of 1073 K (800 C). Al–2 wt% Sc master alloy was added to A356 and A356–10 wt% TiB2 melt to introduce 0.2 and 0.4 wt% Sc in the alloy and the composite. Addition of Sc reduced the secondary dendrite arms spacing (SDAS) by 50% and changed the Si morphology from needle-like to ﬁne spheroidal particles. Microstructure of Sc modiﬁed alloys which were cast for different holding times of 0, 30, 60 and 120 min indicated that there was no fading or poisoning effect on the SDAS and eutectic Si morphology. Hardness was found to increase due to addition of Sc and TiB2 Pin-on-disk wear tests indicated that Sc addition increase the wear resistance of A356 alloy but reduced the wear resistance of A356–TiB2 composite.

The present investigation studies the prospects of using nanoparticles as reinforcement agents to
gain improved performance of A356 Al cast alloy by adding up to 5% Al2O3 and TiO2 particles.
The particles size was intentionally reduced from 10 mm to 500 nm to 40 nm. To evaluate the
results, the alloys were further characterised by various metallurgical and mechanical
characterisation methods. The results showed that introducing nanoparticles into semisolid
slurries has a beneficial effect on optimising strength–ductility relationship in Al–Si cast alloys. The
new material showed higher strength values with improved ductility compared to the monolithic
alloy under the same casting conditions. Those particles were incorporated and entrapped within
the interdendritic and/or grain boundary interface, as well as within the grains, developed during
solidification.

The article is devoted to the performance restoration technology development of the aluminum radiator of tractor «John Deer 7830». The distinctive feature of the suggested technology is cold gas spraying application, which provides air tightness restoration of the radiator made of thin‐walled aluminum parts and having complicated form that causes troubles to technological operation fulfilment. The carried out experimental investigations resulted in determining rational technological parameters of gas dynamic spraying: nozzle angle of the facility and the distance from the nozzle exit to the spraying surface, providing optimal mechanical characteristics of the repair coating.

This research was undertaken to investigate the effect of nickel macro-addition on the structure and mechanical properties of aluminium bronze. Sand casting method was used in the production of a dual-phase aluminium bronze alloy with pre-selected composition of 10% Al-content. The properties studied were tensile strength, yield strength, percentage elongation using universal tensile testing machine (SRNO0723), impact strength using charpy machine (U1820) and hardness using Brinell hardness tester model B 3000(H). The tests were conducted according to BS 131-240 standards. The specimens were prepared by doping 1.0-10wt% of nickel into Cu-10%Al alloy at 1.0 percent interval. Microstructural analysis was conducted using L2003A reflected light metallurgical bench microscope and PHENOM ProX scanning electron microscope. Results obtained showed that optimally improved mechanical properties were achieved at 4wt% nickel addition with respect to ultimate tensile strength and %elongation. Hardness on the other hand, decreased with increase in nickel content while impact strength increased with increase in composition of nickel from 1-10wt%. Microstructural analysis revealed the presence of primary α-phase, β-phase (intermetallic phases) and fine stable reinforcing kappa phase and these phases gave rise to the enhanced mechanical properties. This research have established that aluminium bronze doped with nickel increased the tensile strength, ductility, and impact strength and reduces hardness and is therefore recommended for applications in automobiles and allied engineering industry.

- by Francis O Edoziuno and +3
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- Physical Metallurgy, Aluminium Alloy Development

Knowing the contact stresses in the dies during the extrusion of aluminum is very important, because it provides information to design new tools and materials, as well as to predict the wear and the useful life of these dies, being much more important in the case of extrusion. of precision profiles, where minimum wear is required. Thus, in this work, in order to determine the contact stresses on the die surface during aluminum extrusion, a simulation was performed using the Finite Element Method and the equation by ARCHARD. The Finite Element code "LUSAS" was used with which all the components were modeled independently in three dimensions in space using hexagonal elements of eight nodes (HX8) and put in contact later, considering the main characteristics of the extrusion process as friction. , material plasticity, etc., which causes a non-linear simulation procedure. The results obtained are in the form of tables and graphs and were compared with others obtained experimentally, confirming the validity of the model.

Friction Stir Welding pertama kali dikenalkan oleh The Welding Institute (TWI) pada tahun 1991 di Inggris. Friction Stir Welding merupakan salah satu dari beberapa welding method yang menggunakan fase solid-state atau dapat juga dibilang sebagai fase intermetallic dari material yang tidak pada lazimnya dipakai dalam menyambungkan logam. Friction stir welding (FSW) mulai banyak dikembangkan karena merupakan metode yang dapat menyambungkan dua buah material yang berbeda jenis. Untuk saat ini metode FSW terus dikembangkan agar nantinya didapatkan hasil pengelasan yang optimal, maka dari itu penelitian ini dibuat dan dikhususkan untuk mencari parameter permesinan yang sesuai untuk menyambungkan material yang berbeda. Penelitian ini menggunakan sambungan butt joint dengan material aluminium dan tembaga murni dengan parameter permesinan yakni kecepatan spindle 1096 rpm; 1452 rpm; 1842 rpm; dan 2257 rpm; 2906 rpm. Dari penelitian didapatkan hasil kekuatan tarik optimal pada kecepatan putaran spindle 1452 rpm dengan kekuatan tarik rata-rata sebesar 61.72 MPa.

- by sri haslah
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- Friction Stir Welding, Aluminium Alloy Development, Copper Alloys

Understanding the composition evolution of grain boundaries and grain boundary precipitation at near-atomic scale in aluminum alloys is crucial to tailor mechanical properties and to increase resistance to corrosion and stress corrosion cracking. Here, we elucidate the sequence of precipitation on grain boundaries in comparison to the bulk in a model Al-Zn-Mg-Cu alloy. We investigate the material from the solution heat treated state (475 C), through the very early stages of aging to the peak aged state at 120 C and further into the overaged regime at 180 C. The process starts with solute enrichment on grain boundaries due to equilibrium segregation accompanied by solute depletion in their vicinity, the formation of GuinierePreston (GP) zones in the solute-enriched grain boundary regions, and GP zones growth and transformation. The equilibrium segregation of solutes to grain boundaries during aging accelerates this sequence compared to the bulk. Analysis of the ~10 nm wide precipitate-free zones (PFZs) adjacent to the solute-enriched grain boundaries shows that the depletion zones are determined by (i) interface equilibrium segregation; (ii) formation and coarsening of the grain boundary precipitates and (iii) the diffusion range of solutes in the matrix. In addition, we quantify the difference in kinetics between grain boundary and bulk precipitation. The precipitation kinetics, as observed in terms of volume fraction, average radius, and number density, is almost identical next to the depletion zone in the bulk and far inside the bulk grain remote from any grain boundary influence. This observation shows that the region influenced by the grain boundaries does not extend beyond the PFZs.

- by Dierk Raabe
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- Thermodynamics, Phase Transformations, Kinetics, Aluminium Alloys