Thermal stability of an composite processed by powder metallurgy

Abstract

Abstract The potential of Al Ni 3 Al composites for high-temperature applications, especially when friction is involved, is currently being explored. In this work, the thermal stability of an Al Ni 3 Al composite obtained by extrusion of Al and 5 vol% of spherical Ni3Al powder particles was investigated at temperatures up to 500 °C. The metal/intermetallic composite proved stable up to 300 °C. At higher temperatures, dissolution of Ni3Al particles occurred with formation of concentric layers of Al3Ni and Al3Ni2 phases. The amount of Ni aluminides for each annealing condition was determined by applying a specifically developed mathematical procedure. Dissolution of Ni3Al up to 500 °C was found to obey a parabolic-type law with an activation energy of 156 kJ mol−1. Activation energies for growth of Al3Ni2 and Al3Ni were 209 and 110 kJ mol−1, respectively, in agreement with the literature. The thermal stability shown by this composite makes it a good candidate for high-temperature applications up to 300 °C.