Microstructure of tungsten metal alloys produced by Field Assisted Sintering Technology (FAST)

Abstract

Tungsten (W) refractory alloys are of high importance in the development of high temperature application products seen in furnace elements, the aerospace industry, and many other areas. Traditional manufacturing processes produce tungsten alloys with undesirable mechanical properties due to a large grain microstructure. Commercial sintering techniques yield low density products due to the poor sinterability of tungsten alloys. Field Assisted Sintering Technology (FAST) is used in this work to produce tungsten alloys with high density, and acceptable microstructures. Limited research has been done with hafnium carbide (HfC) as grain growth inhibitors. 100% W, W-1vol%HfC, W-2vol%HfC, and W-5vol%HfC were sintered at 2100 °C, 35 MPa, for 25 min. Microstructure of each composition was characterized and reported. For volume additions of 2% or more of hafnium carbide shows a decrease in grain size of over 67% while increasing the hardness by over 19% when compared with a pure tungsten composition. These results include imaging between the W-HfC interfaces gathered from high resolution transmission electron microscopy (HRTEM).