Measurements of the microhardness, electrical and thermal properties of the Al-Ni eutectic alloy

Al-5.7 wt% Ni eutectic alloy was directionally solidified upward with different temperature gradients (0.83-4.02 K/mm) at a constant growth rate (0.008 mm/s) and with different growth rates (0.008-0.483 mm/s) at a constant temperature gradient (4.02 K/mm). Microhardness (HV) and electrical resistivity (rho) of directionally solidified samples were measured using microhardness test device and a standard d.c. four-point probe technique, respectively. Dependency of the microhardness and electrical resistivity on the solidification processing parameters (temperature gradient, G and growth rate, (V) were analyzed. According to these results, it has been found that the values of HV and rho increase with the increasing values of G and V. Variations of electrical resistivity and electrical conductivity (sigma) for casting Al-Ni eutectic alloy were also measured at the temperature in range 300-720 K. The enthalpy of fusion (Delta H) for the Al-Ni eutectic alloy was determined by differential scanning calorimeter (DSC) from heating trace during the transformation from solid to liquid. (C) 2011 Elsevier Ltd. All rights reserved.