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

Thermal Stability of an Al/Ni3Al Composite Processed by Powder Metallurgy. Lieblich, M., González-Carrasco, J.L., Caruana, G.: Intermetallics, 1997, 5[7], 515-24