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 mu m/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 mu m/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 (lambda) were found to be HV = k(1) V(0.10), HV = k(2) G(0.13) and HV = k(3) lambda(-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. (C) 2011 Elsevier B. V. All rights reserved.