Effect of sintering temperature on the microstructures and properties of 93W-4.9Ni-2.1Fe alloy by spark plasma sintering

A 93W-4.9Ni-2.1Fe heavy alloy was prepared by spark plasma sintering with 93W-4.9Ni-2.1Fe composite powders synthesized by high energy ball milling as raw materials,and the influences of sintering temperature on its microstructure and properties were studied.The fracture morphology and composition of the alloy were measured by scanning electron microscopy and energy dispersive spectrometry,respectively.It is shown that the properties of samples change significantly with sintering temperature,and the tensile strength appears a peak of 981 MPa at 1 350℃,where the relative density and the W crystalline grain size arrive at 98.9% and 5 μm,respectively.Ni element in samples tends to volatilize when the sintering temperature reaches 1 375℃,and it is completely volatilized when the sintering temperature hits 1 425℃.The fracture mode of the alloy sintered from 1 250℃ to 1 350℃ changes from W-W cleavage to tungsten-matrix fracture,while it transforms into W-W cleavage again beyond 1 350℃.Grain growth can be effectively inhibited by spark plasma sintering,which prompts fine grain strengthening of the alloy.