Microstructural evolution of ZrB2–MoSi2 composites during heat treatment

The microstructural evolution of ZrB2–20 vol% MoSi2 composites during heat treatment with and without pressure at 2000 °C for 1 h in argon was investigated. Results showed the materials exhibited a multiphase layered structure after heat treatment without pressure. From surface to center, the layered structure consisted of (1) a Mo layer, (2) a Si layer, (3) a ZrB2–MoSi2 layer and (4) a partially MoSi2-depleted ZrB2 layer. The formation mechanism of layered structure was analyzed. After heat treatment with pressure, the materials with high toughness mainly contained ZrB2 phase.