Variations of microhardness with solidification parameters and electrical resistivity with temperature for Al–Cu–Ag eutectic alloy

Abstract

Al–Cu–Ag eutectic alloy was directionally solidified upwards with different growth rates (1.83–498.25 μm/s) at a constant temperature gradient (8.79 K/mm) and with different temperature gradients (3.99–8.79 K/mm) at a constant growth rate (8.30 μm/s) by using a Bridgman type directional solidification apparatus. The dependence of microhardness (HV) on the growth rate (V), temperature gradient (G) and microstructure parameter (λ) were found to be HV = k 1 V 0.10, HV = k 2 G 0.13 and HV = k 3 λ −0.22, respectively. The electrical resistivity of the Al–Cu–Ag eutectic cast alloy increases linearly with the temperature in the range of 300–780 K. The enthalpy of fusion and specific heat change during melting for same alloy were also determined to be 223.8 J/g, and 0.433 J/g K, respectively by a differential scanning calorimeter from heating curve during the transformation from eutectic solid to eutectic liquid.