Investigation of the microstructure and properties of a ZrC-reinforced TZM molybdenum alloy

Abstract

TZM-ZrC composites with different particle content were produced by high-energy ball milling and discharge plasma sintering technology. The density, microstructure and phase composition of the composites with different particle content were investigated. The microhardness and compressive strength at room and high temperature were tested. The strengthening mechanism was explored. The grain size and density of the composites gradually decrease as the ZrC content increase. The addition of ZrC particles provides C element to the matrix, and in situ reacts with the matrix Mo to form Mo₂C and ZrC_0.7. The generated reinforced phase and the unreacted stable carbide particles coexist in the grain and at the grain boundaries of the Mo matrix, which inhibit the growth of the grains. The average microhardness of TZM-ZrC composites reaches 670.66 HV, and the compressive strength at room temperature and high temperature (600 °C) is about 2200 MPa and 2000 MPa when the ZrC particle content is 10 %. The excellent mechanical properties and thermal stability of the TZM-ZrC composites are attributed to a synergistic effect of nano-scale dispersion strengthening of ZrC particles and fine-grain strengthening. The study can be used to develop other refractory alloys that have both high strength and high thermal stability for high-temperature applications.