Elevated temperature mechanical properties of MoSi2/Si3N4, MoSi2/SiC composites produced by self-propagating high temperature synthesis

Abstract

MoSi₂/Si₃N₄ and MoSi₂/SiC composite powders were produced via a novel self-propagating high temperature synthesis technique (SHS) and consolidated both by hot-pressing and plasma spraying. Mechanical testing subsequently was performed under four-point bending at a variety of elevated temperatures and strain rates. Damage accumulation in the hot-pressed materials, either by particle cracking or particle/matrix separation, resulted in composite mechanical properties that were reduced below the level of the unreinforced material. Plasma sprayed materials showed power-law hardening behaviour caused by Mo₅Si₃ precipitates and increased strain tolerance because of the fine grain size and reduced yield strength of the matrix.