Effect of hot rolling and annealing on the mechanical properties and thermal conductivity of W-0.5 wt.% TaC alloys

摘要

The mechanical properties and thermal conductivity of W-0.5 wt.% TaC alloys prepared by spark plasma sintering as well as ordinary sintering followed by hot rolling and annealing treatment, respectively, were investigated. Tensile tests indicate that below 600 degrees C there is no tensile plastic deformation while at 700 degrees C the total elongation of spark plasma sintered (SPSed) W-0.5 wt.% TaC is up to 36%, which is about 3.3 times that of spark plasma sintered W samples. In contrast, the tensile strength and total elongation of rolled W-0.5 wt% TaC are 717 MPa and 10.7% at 250 degrees C, respectively. The ductile-brittle transition temperature (DBTT) of rolled W-0.5 wt% TaC is between 200 degrees C and 250 degrees C, about 300 degrees C lower than that of spark plasma sintered W-0.5 wt.% TaC (similar to 600 degrees C). Annealing decreases the DBTT (similar to 200 degrees C) and improves thermal conductivity from 175 to 186 W/m.K at room temperature. Microstructure analyses indicates that TaC could purify and strengthen grain boundaries by capturing impurity oxygen in tungsten to form Ta2O5. The results indicate that strength, ductility and thermal conductivity can be improved by purifying, hot rolling and subsequent annealing. (C) 2015 Elsevier Ltd. All rights reserved.