Formation of MoSi₂-WSi₂ Alloy Powder by Carbothermal Reduction Method

Abstract

The preparation of MoSi₂-WSi₂ alloy powder by a carbothermal reduction process was investigated using ammonium paramolybdate, ammonium paratungstate, quartz and active carbon in Ar+H₂ atmosphere. The optimum starting composition for preparing MoSi₂-50mol% WSi₂ powder was Mo:W:Si:C=1:1:7:17. Mo₂C and WC appeared at a low temperature in the course of heating. At 1400°C an alloy of the lower silicides (Mo₅Si₃, W₅Si₃) was formed, subsequently changing into a MoSi₂-WSi₂ alloy. The alloy particles were fine with a size of 0.5-2μm. The sintered body exhibited a homogeneous distribution of Mo and W compared with a sintered body obtained from a mixture of coarse MoSi₂ and WSi₂ particles.