Fabrication of W–Ni–Fe alloys with gradient structures

A sintering couple of green compacts with compositions of 88W–5Mo–4.9–2.1Fe and 93W–4.9Ni–2.1Fe respectively, were processed by liquid phase sintering. The microstructure and content of binding phase at different regions along the direction perpendicular to the original interface were investigated by scanning electron microscopy (SEM). The distribution of Mo content in composite was determined by energy dispersive analysis (EDS) and the micro hardness in different regions were measured by Vickers micro hardness tester. Results show that the grain size, volume fraction of binding phase and micro hardness vary gradually due to the graded distribution of molybdenum, which also introduces a solid/liquid interfacial tension gradient and the unbalanced liquid phase pressure serving as the driving force for liquid phase migration during liquid phase sintering.

► We investigated molybdenum distribution, grain size, micro hardness, and the distribution of binding phase in 88W-5Mo-4.9-2.1Fe /93W-4.9Ni-2.1Fe diffusion couple.
► The grain size, volume fraction of binding phase and micro hardness vary gradually due to the graded distribution of molybdenum.
► The gradient of interfacial tension, caused by the graded distribution of molybdenum, is the driving force for liquid phase migration during sintering.