Interdiffusion and diffusion structure development in selected refractory metal silicides

摘要: Abstract Solid–solid diffusion couples set up with disks of Mo, W, Re, Nb, or Ta in contact a single crystal MoSi 2 were annealed at selected temperatures between 1300° and 1700°C for structure, determination interdiffusion coefficients energies activation various silicides developed the couples. The analyzed characterized by SEM optical microscopy, microprobe analysis, X-ray diffraction orientation imaging microscopy. From fluxes determined directly from concentration profiles, integrated average effective calculated components binary ternary silicide layers. Mo vs. 5 Si 3 layers non-planar interface morphologies; layer exhibited oriented growth microcracking. W (W,Mo) little structure Re consisted Si, (Re,Mo)Si (Re,Mo) phases cracks blunted layer. Nb (Nb,Mo) phase porosity zone. Layers (Ta,Mo) observed ( Q ) both are to be about 360 450 kJ mol −1 layers, respectively. Values 190 phase, 325 270 phase. For values 300 240 , respectively; is 265 Zero-flux planes (ZFP) uphill (Me,Mo) where Me=W, Ta; these cross coefficient D MoMe as large main MoMo enhanced down Me gradient.