Tungsten-zirconium carbide-rhenium alloys with extraordinary thermal stability

The low recrystallization temperature (1200 degrees C) of pure W is a serious limitation for application as facing plasma materials in fusion reactor. In this paper, W-0.5wt.%ZrC-lwt.%Re (WZR) alloy with recrystallization temperature up to 1800 degrees C was prepared by mechanical milling and spark plasma sintering. The grain size of WZR alloy is about 2.6 mu m, smaller than that of pure W (4.4 mu m), which keeps unchanged until the annealing temperature increases to 1800 degrees C. Tensile tests indicate that the WZR alloys exhibit excellent comprehensive properties: the ductile to brittle transition temperature of WZR is in the range from 400 degrees C to 500 degrees C, about 200 degrees C lower than that of pure W prepared by the same process; the total elongation (TE) of WZR at 600 degrees C is above 30%, which is about 2 times that of pure W (at 700 degrees C). Meanwhile its tensile strength keeps 450 MPa before and after 1800 degrees C annealing as well as its TE increases after annealing. WZR alloy exhibits higher hardness (489HV) than that of pure W (453HV) at room temperature. Microstructure analysis indicates that the strengthening of nano-sized ZrC particles dispersion and Re solid solution improve tensile properties and thermal stability of WZR alloy. (C) 2016 Elsevier B.V. All rights reserved.