Study on the high intensity tungsten alloys with the addition of rhenium metal prepared by microwave sintering

Abstract

Tungsten alloys are widely used in military, industrial and medical fields due to their excellent mechanical properties. However, they also face the problem of insufficient strength in extreme environments at the same time. In this study, green embryos were prepared by powder metallurgy and sintered in a microwave tube furnace at different temperatures. Tungsten alloy samples of 90 W-7Ni-3Fe (90 W) and 90 W-7Ni-3Fe with an additional 1 wt% Re(90 W-Re) were successfully prepared. The surface and cross-sectional morphologies of both were analyzed, and the influence of adding rhenium on the grain size and mechanical properties of tungsten alloys was studied. In this experiment, 90 W-Re achieved a density of 98.93 % at 1475 °C and a maximum bending strength of 2024.1 MPa at 1500 °C, which was 229.1 MPa higher than that of 90 W under the same conditions. It was explored that with the increase of temperature, the fracture mode changed from being dominated by intergranular fracture to transgranular fracture and the dissociation of tungsten from the binder phase γ(Ni, Fe) was dominated. Comprehensively considered, 90 W and 90 W-Re were held at 1475 °C for 10 min to obtain the optimal sintering points of this experiment. The preparation of 90 W-Re through microwave sintering provides a new way to improve the bending strength of tungsten alloys.