Impression Creep Behavior of Atmospheric Plasma-Sprayed and Hot Pressed MoSi₂/Si₃N₄

The use of MoSi₂ as a high temperature oxidation resistant structural material is hindered by its poor elevated temperature creep resistance. The addition of second phase Si₃N₄ holds promise for improving the creep properties of MoSi₂ without decreasing oxidation resistance. The high temperature impression creep behavior of atmospheric plasma sprayed (APS) and hot pressed (HP) MoSi₂/Si₃N₄ composites was investigated. Values for steady state creep rates, creep activation energies, and creep stress exponents were measured. Grain boundary sliding and splat sliding were found to be the dominant creep mechanisms for the APS samples while grain boundary sliding and plastic deformation were found to be the dominant creep mechanisms for the HP samples.