Microstructure, Mechanical, Electrical and Thermal Properties of the Al-Si-Ni Ternary Alloy (original) (raw)
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Measurements of Microstructural, Mechanical, Electrical, and Thermal Properties of an Al–Ni Alloy
International Journal of Thermophysics, 2013
The Al-7.5 wt% Ni alloy was directionally solidified upwards with different temperature gradients, G (0.86 K • mm −1 to 4.24 K • mm −1) at a constant growth rate, V (8.34 µm • s −1). The dependence of dendritic microstructures such as the primary dendrite arm spacing (λ 1), the secondary dendrite arm spacing (λ 2), the dendrite tip radius (R), and the mushy zone depth (d) on the temperature gradient were analyzed. The dendritic microstructures in this study were also compared with current theoretical models, and similar previous experimental results. Measurements of the microhardness (HV) and electrical resistivity (ρ) of the directionally solidified samples were carried out. Variations of the electrical resistivity (ρ) with temperature (T) were also measured by using a standard dc four-point probe technique. And also, the dependence of the microhardness and electrical resistivity on the temperature gradient was analyzed. According to these results, it has been found that the values of HV and ρ increase with increasing values of G. But, the values of HV and ρ decrease with increasing values of dendritic microstructures (λ 1 , λ 2 , R, and d). It has been also found that, on increasing the values of temperature, the values of ρ increase. The enthalpy of fusion (H) for the Al-7.5 wt%Ni alloy was determined by a differential scanning calorimeter from a heating trace during the transformation from solid to liquid.
International Journal of Cast Metals Research, 2017
In this work, effect of alloying elements (X = Cu, Co, Ni, Sb and Bi) and growth rates on the microstructure, physical properties (electrical resistivity, enthalpy and specific heat) of the directionally solidified Al-Si eutectic alloy have been investigated. Al-12.6Si-2X (wt. %) samples were prepared using metals of 99.99% high purity in the vacuum atmosphere. These alloys were directionally solidified under constant temperature gradient, G (7.80 K/mm) and different growth rates, V (8.3-166.0 μm/s). Flake spacing (λ) and electrical resistivity (ρ) were measured from the solidified samples. The variation of electrical resistivity with temperature in the range of 300-500 K for alloying elements in the Al-Si eutectic cast alloy was also measured. The enthalpy of fusion (ΔH) and specific heat (C p) for the same alloy were determined by a differential scanning calorimeter from the heating curve during the transformation from solid to liquid.
Metallic Materials
The effect of Si content (0.5, 1.5, and 5 wt.%) and growth velocity on the microstructure, microhardness, ultimate tensile strength, electrical resistivity, enthalpy, and specific heat properties of the directionally solidified Al-Mn eutectic alloy have been investigated. Al-1.94Mn-xSi (x = 0.5, 1.5, 5 wt.%) samples were prepared from pure metals (99.99 % purity) under the vacuum. These alloys were directionally solidified under constant temperature gradient G (4.9 K mm −1) and different growth velocities V (from 8.3 to 978 µm s −1) in a Bridgman-type growth apparatus. Measurements of primary dendrite arm spacing (λ), microhardness (HV), ultimate tensile strength (UTS) and electrical resistivity (ρ) of the samples were carried out and then expressed as functions of growth velocity and Si content (Co). Additionally, the enthalpy of fusion (ΔH) and specific heat capacity (Cp) for the same alloys were determined by a differential scanning calorimeter (DSC) from the heating curves. It has been found that the values of HV, UTS, and ρ increase with increasing values of V and Co. On the contrary, the values of λ decrease with increasing V. The increasing Si content in Al-Mn leads to a decrease of ΔH and Cp.
International Journal of Engineering Research, 2015
This Paper investigated effects of annealing and age hardening on the ultimate tensile strength (UTS) and electrical conductivity of aluminium-nickel cast using sand mould. Pure aluminium melt was alloyed with nickel, which was added in 2% to 10% step 2. Annealing and age hardenings were carried out and obtained results showed that Al-2%Ni alloy has the highest UTS of 604.44MPa. On the other hand, Al-6%Ni Annealed alloy has the highest electrical conductivity, with a value of 6.15 × 10 7 S/m. The Al-4%Ni alloy combined both high strength and conductivity, having UTS of 603.28MPa and electrical conductivity of 5.69 × 10 7 S/m.
Materials Research
Metals solidification involves the transformation of the molten metal back into the solid state. Solidification structures impact heavily on the final product's characteristics. The microstructure effects on metallic alloys properties have been highlighted in various studies and particularly the dendrite arm spacing influence upon the mechanical properties such as tensile strength has been reported. In the present investigation, Al-10wt%Si-2wt%Cu and Al-10wt%Si-5wt%Cu alloys were directionally solidified upward under transient heat flow conditions. The experimental results include solidification thermal parameters such as tip growth rate and cooling rate, optical microscopy, volume fraction of the eutectic mixture, primary dendritic arm spacing and ultimate tensile strength. Experimental growth laws of primary dendrite arm spacing as a function of the solidification thermal parameters are proposed. The Hall-Petch mathematical expressions were used to correlate the ultimate tensile strength as a function of the primary dendritic arm spacing. It was found that the alloy with higher copper content had a more refined structure. More refined structures had higher ultimate tensile strength values.
The International Conference on Applied Mechanics and Mechanical Engineering, 2018
Eutectic Al-13 wt. % Si and hypereutectic Al-16 wt. % Si were prepared by using permanent mould casting technique. Effect of the cooling technique on the cast microstructure, mechanical properties, and electrical conductivity of Al-Si alloys was investigated by using the conventional water-cooled and air-cooled methods. The mechanical properties such as the yield stress, tensile strength, hardness, and impact energy were measured at various cooling methods. Microstructure with scanning electron microscope (SEM) and Energy dispersive spectrometer (EDS) analysis of Al-Si alloys have been studied. In addition, the hardness after solution treatment at 529 °C for 2 h and artificial ageing at various temperatures 180 °C and 210° C for aging time 2-10 h was measured. The results show enhancement in the mechanical and electrical properties for the eutectic Al-13 wt. % Si and hypereutectic Al-16 wt. % Si alloys for the water-cooled over the air-cooled technique. In addition, the largest value of the impact energy (4.91 J) was obtained for the eutectic Al-13 wt. % Si alloys compared to the hypereutectic Al-16 wt. % Si alloys at 3.09 J for watercooled-medium. The total solidification time (TST) of Al 13% wt. Si was longer than that time for the hypereutectic Al 16% wt. Si at various cooling mediums. Aging studies of Al-Si alloys with aging temperatures 180 ºC and 210 ºC show that the hardness values increased as the silicon content increases. For hypereutectic Al-16 wt. % Si at aging temperature 180 ºC and aging time 4 h by using water-cooled technique, it was observed that the maximum hardness value reached to 100 HRD compared that value was 87 HRD for the eutectic Al-13 wt. % Si alloy.
Properties Comparison of Ti-Al-Si Alloys Produced by Various Metallurgy Methods
Materials, 2019
Melting metallurgy is still the most frequently used and simplest method for the processing of metallic materials. Some of the materials (especially intermetallics) are very difficult to prepare by this method due to the high melting points, poor fluidity, or formation of cracks and pores after casting. This article describes the processing of Ti-Al-Si alloys by arc melting, and shows the microstructure, phase composition, hardness, fracture toughness, and compression tests of these alloys. These results are compared with the same alloys prepared by powder metallurgy by the means of a combination of mechanical alloying and spark plasma sintering. Ti-Al-Si alloys processed by melting metallurgy are characterized by a very coarse structure with central porosity. The phase composition is formed by titanium aluminides and titanium silicides, which are full of cracks. Ti-Al-Si alloys processed by the powder metallurgy route have a relatively homogeneous fine-grained structure with higher...
The effect of main alloying elements on the physical properties of Al–Si foundry alloys
Materials Science and Engineering: A, 2013
In this study we describe the effect of the main alloying elements Si, Cu and Ni on the thermal properties of hypoeutectic and near-eutectic Al-Si foundry alloys. By means of systematic variations of the chemical composition, the influence of the amount of 'second phases' on the thermal conductivity, thermal expansion coefficient, and thermal shock resistance is evaluated. Thermodynamic calculations predicting the phase formation in multi-component Al-Si cast alloys were carried out and verified using SEM, EDX and XRD analysis. The experimentally obtained data are discussed on a systematic basis of thermodynamic calculations and compared to theoretical models for the thermal conductivity and thermal expansion of heterogeneous solids.
Materials Research
Ternary Al-9.0wt%Si-4.0wt%Cu alloy was solidified in a vertical directional solidification system under unsteady-state heat flow conditions. The resulting dendritic morphology and microsegregation were investigated. A more detailed analysis was dedicated to the microsegregation phenomena where a multielement interaction was observed. The solidification parameters such as: solidification speed (V L) and cooling rate () were determined from the cooling curves obtained during the solidification process. The thermal variables effect on the dendritic morphology is presented. The measurements of tertiary dendrite arm spacing (λ 3) and microsegregation were performed for different positions along the casting. The experimental curves for microsegregation were obtained for Si and Cu from the center of dendritic tertiary arm to the next nearest tertiary arm. The solidification speed (V L) influence is "built into" the effective partition coefficient (K ef_Cu and K ef_Si) that has been determined for the range of V L and microsegregation curves are calculated by Scheil's equation for comparison with experimental data. Good agreements of the Scheil's equation with experimental data on microsegregation curves of the Si and Cuwere obtained when effective partition coefficient (K ef_Cu and K ef_Si) is taken into consideration. The multielement interaction effect on the Si microsegregation is investigated. Experimental results show that, Cu-rich dendrites were accompanied by minute amounts of Si. The concentration profiles obtained experimentally point to a strong negative correlation between Si and V L on ternary Al-9.0wt%Si-4.0wt%Cu alloy.
Journal of Alloys and Compounds, 2017
In this research, effect of alloying elements (X=Cu, Co, Ni, Sb and Bi) and growth rates on the microstructure and mechanical properties (microhardness and tensile strength) of the directionally solidified Al-Si eutectic alloy have been investigated. Al-12.6Si-2X (wt. %) samples were prepared using metals of 99.99% high purity in the vacuum atmosphere. These alloys were directionally solidified under constant temperature gradient and different growth rates (8.3-166.0 µm/s) by using a Bridgman-type growth apparatus. Interflake spacings, microhardness and tensile strength were expressed as functions of growth rate. The effects of alloying elements and growth rates on microstructure, microhardness and tensile strength were determined. According to experimental results, the microstructures, microhardness and tensile strength of the solidified Al-SiX samples changes with alloying elements (Cu, Co, Ni, Sb and Bi) and the growth rates. The results obtained in this work have been compared with the similar experimental research in the literature.