Effect of heat treatment on microstructure of near-eutectic Al-Ni-Mn alloy, and determination of mechanical and thermoelectrical properties

Abstract

This study examined the impact of solution heat treatment on the microstructure, mechanical characteristics, thermophysical properties, and electrical resistivity of an Al-Ni-Mn near-eutectic alloy. The investigation focused on varying temperatures and holding periods. The composition of the Al-Ni-Mn near-eutectic alloy system was chosen as Al-5.3%Ni-1.0%Mn (wt). In the non-heat-treated sample, the matrix phase (-Al) is in equilibrium with the intermetallic Al9(Mn,Ni)2 and Al3Ni phases. The hardness value of the non-heat-treated sample (49.8 kg/mm2) increased to 70.1 kg/mm2 with 2 hours of solution heat treatment at 570oC and then 8 hours of artificial aging at 180oC. The hardness value increased by approximately 41%. TE: 651.81oC for the non-heat-treated sample and TE:648.79oC for the heat-treated sample. Fusion enthalpy (H) value was determined as 336.79 (J/g) for the non-heat-treated sample and 516.36 (J/g) for the heat-treated sample. Heat Capacity (Cpl) value was found to be 0.364 J/g.K for the non-heat-treated sample and 0.560 J/g.K for the heat-treated sample. The electrical resistivity value of the 2 hours’ solution heat-treated sample at 600oC reached its highest value.