Synthesis and Sintering of Ultrafine MoSi2-WSi2 Composite Powders

In this work, ultrafine MoSi2-WSi2 composite powders with different volume fractions of WSi2 were controllably prepared via silicothermic reduction of MoS2-WS2 mixtures. The micromorphology observation shows that the as-prepared particles inherited the sheet-like morphology of MoS2 or WS2 and consisted of ultrafine grains. The vacuum pressureless sintering results indicated that the addition of WSi2 can greatly enhance the mechanical properties of the MoSi2 matrix, attributed to the solid solution strength of WSi2, grain refinement and increase of relative density of the samples caused by the introduction of Fe element. When the volume fraction of WSi2 was between 1% and 20%, after sintering at 1500°C for 2 h, the MoSi2-20 vol.% WSi2 composite sample had the highest densification degree, hardness, and flexural strength of 95.21%, 10.72 GPa and 297 MPa, respectively. The MoSi2-10 vol.% WSi2 composite sample had a maximum fracture toughness value of 7.28 MPa m1/2.