Reduced Activation W Alloys for Plasma Facing Materials

In order to improve the in-service characteristics of W, thorough research on W-based composites, new W alloys and functionally graded materials are in progress. The limitations of conventional W alloys such as such as high brittleness, high activation energy for dislocation's mobility, reduced mechanical strength due to reaction phases, poor fabricability, defective passive layer, poor workability and unavailability of good number of alloy systems have persuaded us to divert research focus towards W-based high entropy alloys. The core effects of high entropy alloys include enhanced mixing entropy, sluggish diffusion, severe lattice distortion and cocktail effects. These key characteristics of high entropy alloys promote the formation of solid solution of 5 to 13 principle elements with exceptionally high strength, hardness, thermal stability, wear resistance, fatigue and creep resistance. Although the synthesis and exploitation of high entropy alloys have been in progress, this study comprises of our work in which we developed a reduced activation W-based high entropy alloy by not incorporating Mo, Cu, Nb and by reducing Ti content. In this research a powder metallurgical technique has been successfully used for producing novel W-based alloy with enhanced mechanical properties. An undiscovered potential of an unusual and so far disregarded powder metallurgical technique i. e. simple mixing in the development of W based material for future fusion power plants has been exploited by fabricating and analyzing a novel tungsten based high entropy alloy system x%W-(100-x)/4%(TaTiCrV). The characterization of HEA samples by XRD showed BCC crystal structure of the alloys. Microstructural examination SEM-EDS revealed the presence of bright and dark regions as W and Ti-rich phases, respectively. The evaluation of microstructures by using image processing software and Vickers hardness via micro-Vickers hardness tester showed the similar dependency of phase fraction and hardness on composition and sintering temperature