THE MICROSTRUCTURE AND INTERFACE BEHAVIOR OF NI NIAL COMPOSITES PRODUCED BY THE EXPLOSIVE COMPACTION OF POWDERS/

Explosive compaction of Ni and NiAl powders was utilized for the proce ssing of Ni/NiAl metal-matrix composites containing up to 57 vol % NiA l particulate. The microstructure, the Vickers microhardness and the N i/NiAl interfacial bonding strength were studied. The resulting micros tructure had a very low volume fraction of porosity (similar to 1 vol %) except for the melting zone formed in the upper portion of a cylind rical specimen. NiAl particles underwent welding during explosive comp action; this was particularly pronounced at the highest volume fractio ns of NiAl. The lowest microhardness of the Ni matrix was observed in the central portion of a cylindrical specimen. Other parts of the matr ix were heavily cold-worked, indicating that a recrystallization had o ccurred in the centre. NiAl particles were also highly cold-worked reg ardless of their volume fraction in the composite. The Ni/NiAl interfa cial bond strength, measured by the indentation debonding technique, w as highest in a composite containing 57 vol % of NiAl particulate.