Room and high temperature tensile behaviour of a P/M 2124/MoSi2 composite at different heat treatment conditions

In the present work, a 2124/15 vol%MoSi₂ composite was obtained by powder metallurgy. Its microstructure and mechanical properties were investigated at room and at high temperature (up to 200°C) in conditions T351, T4 and after heat treatments at 495°C for up to 100 h. Up to 150°C, tensile properties of 2124/MoSi₂ in T351 resulted similar to those of a ceramic reinforced 2124/SiC composite. Yield stress of the 2124/MoSi₂ material, after heating at 495°C for up to 100 h, resulted higher than that of the monolith 2124 alloy heated for the same periods. No diffusion reaction phases were formed surrounding the MoSi₂ reinforcing particles during such long exposures to high temperature. Only at 100 h, large plate-like precipitates that contain Al, Cu, Mg and Si appeared. The high thermal stability of this 2124/MoSi₂ composite and its good mechanical properties at room and at elevated temperature makes MoSi₂ intermetallic a competitor of ceramic reinforcements.