Structure, Phase Composition, and Hardness of Ni3Al–TiC Composite Fabricated by Thermal Explosion of Nickel, Aluminum, and Titanium Carbide Powder Mixture

Abstract

Using scanning electron microscopy, X-ray phase analysis, and hardness measurement we investigated the structure, phase composition, and mechanical properties of Ni₃Al–TiC composite (TiC content varied in the interval from 0 to 30 vol %) fabricated by self-propagating high-temperature synthesis in the thermal explosion mode from a powder mixture of nickel, aluminum, and titanium carbide. It was found that the synthesis of Ni₃Al intermetallic compound occurred almost completely when TiC content in the green powder mixture was up to 15 vol %. TiC particles were arranged in clusters and individually. Each particle, including in the clusters, was surrounded with the matrix material. The hardness of the composite essentially increased with an increase in the TiC content in the green powder mixture up to 10 vol %. Then the hardness gain was slow. The matrix of the composite contained Ni₃Al and NiAl intermetallic phases as well as unreacted nickel when the fraction of TiC in the green powder mixture increased to 30 vol %. TiC particles were adjacent to each other in the clusters and there was a free volume between them. Thus, it was concluded that the synthesis of Ni₃Al–TiC composite under thermal explosion condition from the mixture of nickel, aluminum, and titanium carbide powders satisfactorily took place when the fraction of titanium carbide in the green powder mixture was 15 vol % and less.