Toughening of a low-activation tungsten alloy using tungsten short fibers and particles reinforcement for fusion plasma-facing applications

Abstract

Novel low-activation tungsten (W) alloy-based composites are investigated here. A W0.5TaTiVCr matrix (M) was selected due to its promising strength (more than two times that of pure W) and low activation properties. W short fibers (W-sf) or W particles (W-p) were embedded in W0.5TaTiVCr in an effort to improve the fracture strain. Unlike W-fiber-reinforced-W-matrix-composites, near-isotropic composites with nearly full densities were developed via the simple fabrication method (as compared to hot isostatic pressing and chemical vapor infiltration) of elemental powder mixing followed by spark plasma sintering (SPS) at 1600 degrees C. Microstructural characterization reveals randomly dispersed and wellbonded W reinforcements with the matrix, which shows the body-centered cubic (BCC) crystal structure and multiple phases. The fracture strain of W0.5TaTiVCr under compressive stress shows a two-fold improvement from similar to 4.3% to similar to 9.3% due to the addition of 10 wt.%W-p while maintaining a high yield strength of similar to 1900MPa. An addition of 50 wt.%W-p results in similar to 16% fracture strain. The addition of 10 wt.%W-sf results in four times higher fracture toughness (from similar to 7.7 to similar to 29.6MPa . m(1/2)). The mechanisms determining the improvement in the fracture strain and toughness due to the addition of the W-sf and W-p are discussed based on the fracture surface analysis.