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 (Wsf) or W particles (Wp) 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 °C. Microstructural characterization reveals randomly dispersed and well-bonded 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 ~4.3% to ~9.3% due to the addition of 10 wt.%Wp while maintaining a high yield strength of ~1900 MPa. An addition of 50 wt.%Wp results in ~16% fracture strain. The addition of 10 wt.%Wsf results in four times higher fracture toughness (from ~7.7 to ~29.6 MPa · m1/2). The mechanisms determining the improvement in the fracture strain and toughness due to the addition of the Wsf and Wp are discussed based on the fracture surface analysis.

W0.5TaTiVCr-based composite reinforced with W-mesh for fusion plasma-facing applications

“…The fracture toughness of W 0.5 TaTiVCr/10 wt%W mesh composite is shown The initial cracking dissipates the concentrated stress and increases the total displacement before catastrophic failure. The W 0.5 TaTiVCr/W mesh composite exhibits ~20 MPa m 1/2 fracture toughness, which is significantly higher than the fracture toughness of the matrix alone and of pure W (figure 6(c)) [26].…”

“…The boundary/interface between W mesh and W 0.5 TaTiVCr shows notable interdiffusion due to the lack of coating on W mesh (figure 3(a)). A detailed analysis of W 0.5 TaTiVCr/W mesh interface is given in [26].…”

High Temperature Performance of Spark Plasma Sintered W0.5(TaTiVCr)0.5 Alloy

“…The alloy showed increasing yield strength in the range of 1206-2265 MPa with decreasing W content. Amongst these W-based alloys, W 0.5 (TaTiVCr) 0.5 is of particular interest for the fusion applications due to its composition consisting of low activation elements, nearly full relative density, homogeneous microstructure, room temperature compressive strength of~2100 MPa and hardness of~788 HV [42,43]. Moreover, its powder metallurgy fabrication does not require high energy milling and make it energy efficient, cost effective and less time consuming [42,43].…”