Effect of Ta, Nb and Zr additions on the microstructures and mechanical properties of 70 vol% TiC/Al cermets

Abstract

In this work, 70 vol% TiC/Al cermets with the addition of 5 vol% Ta, Nb and Zr elements were successfully fabricated by combustion synthesis and hot-pressing method. Among them, Ta, Nb and Zr elements generated (Ti, X)C (X = Ta, Nb and Zr) solid solutions and Al3X (X = Ta, Nb and Zr) intermediate phases during the reaction process, and refine TiC particles significantly. Especially, Ta and Nb elements decreased the crystallographic mismatch of the Al/TiC interface. The addition of Ta improves the compression properties of TiC/Al cermets at room temperature and high temperature. The addition of Nb and Zr impairs the room temperature compressibility of the TiC/Al cermet, but improves the high temperature (300 °C) compressibility. The strengthening mechanisms of TiC/Al cermets after adding Ta, Nb and Zr were mainly solid solution strengthening, grain refinement strengthening and the reduction of lattice mismatch at the Al/TiC interface. The reduced mechanical properties of TiC/Al cermets at room temperature after the addition of Nb and Zr elements were due to the presence of intermediate phases.