MoSi2-WSi2复合材料自蔓延热爆合成反应热力学

Reaction Thermodynamics of MoSi2-WSi2 Composites in the Thermal Explosion Mode of SHS

摘要:

对Mo-W-Si三元体系自蔓延热爆合成MoSi2-WSi2复合材料的反应吉布斯自由能、反应生成焓和绝热温度进行了理论分析和实验研究,并利用X射线衍射分析和扫描电镜及微区成分分析(EDAX)技术对产物进行了相组成和微区成分分析.结果表明在1685 K(Si熔点)时,MoSi2和WSi2的反应生成焓最大,分别为234.645 KJ/mol和195.670 KJ/mol.当初始温度为1685 K时,体系所有产物均完全熔融.利用自蔓延热爆合成可制备纯净的MoSi2-WSi2复合材料.MoSi2和WSi2以固溶体(Mox,W1-x)Si2的形式存在,但每个晶粒内的成分并不均匀.

Abstract:

The reactive Gibbs free energies, the reactive formation enthalpies and adiabatic temperatures concerning the preparation ofMoSi2-WSi2 composites using elemental powders of Mo, W and Si by the thermal explosion mode of SHS have been theoreticallycalculated and investigated by experiments. XRD, SEM and EDAX have analyzed the phase compositions and micro-area chemicalanalyses of the products. The results show that the reactive formation enthalpies of MoSi2 and WSi2 are biggest, 234.645 kJ/mol and195.670 kJ/mol respectively, when the reactions take place at 1685 K (the melting point of Si). And when the initial temperature is 1685 Kthe products of all systems have fused completely. Pure MoSi2-WSi2 composites are fabricated by the thermal explosion mode of SHS, andMoSi2-WSi2 exists as solid solution of (Mox,W1-x)Si2 while the chemical elements of every grain are not uniform.