Investigation of the effect of solidification processing parameters on microhardness and determination of thermo-physical properties in the Zn-Cu peritectic alloy
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Zn-1.5wt.% Cu peritectic alloy was directionally solidified upward with different growth rates (8.41-661.11 mu m/s) at a constant temperature gradient (7.81 K/mm) and with different temperature gradients (1.99-7.81 K/mm) at a constant growth rate (16.44 mu m/s) using a Bridgman-type directional solidification apparatus. The measurements of microhardness of directionally solidified samples were made by using a microhardness test device. The dependence of microhardness (HV) on the growth rate (V) and temperature gradient (G) were analyzed. According to these results, it has been found that with the increasing the values of V and G the values of HV increase. Variation of electrical resistivity (rho) and electrical conductivity (sigma) with the temperature in the range of 300 similar to 670 K for casting samples were also measured by using a standard d.c. four-point probe technique. The variation of Lorenz coefficient with the temperature was determined by using the measured values of electrical conductivity and thermal conductivity. The enthalpy of fusion and specific heat for same alloy were determined by means of differential scanning calorimeter (DSC) from the heating curve during the transformation from peritectic solid to peritectic liquid. (C) 2009 Elsevier B.V. All rights reserved.