Study on microstructure and mechanical properties of W-Ni₃Al alloys prepared by ball milling and two-step sintering

In this paper, W-Ni₃Al alloys with the different Ni₃Al contents were prepared via ball milling and two-step sintering processes. The relationship of Ni₃Al contents, microstructural evolution, and mechanical properties of W-Ni₃Al alloys were also clarified. The results show that the milled powder has a lamellar structure and cold welding phenomenon. This structure encloses a small amount of ethanol, and this causes an Al₂O₃ phase to form when it undergoes an oxidizing reaction of Ni₃Al with oxygen in ethanol during ball milling and drying. The W-rich phase is the network structure, and this structure is finer and denser with an increase in Ni₃Al contents as a result of the grain refining effect of Al₂O₃ particles and the densification effect of liquid sintering. Under a load, the Al₂O₃ particles at the interface of W/binder phases increase the resistance of crack growth and compressive strain, which improves the mechanical properties and deformability of W-Ni₃Al alloys. The Ni₃Al binder provides a new strategy for improving the mechanical properties of tungsten alloys. (paper)