High Entropy Alloys: Welding

Welding is an essential manufacturing process that often affects the microstructure and/or the mechanical properties of load-bearing metallic material. Thus, weldability assessment of candidate materials is necessary in the development of new alloys and manufacturing of the alloys for intended applications. High entropy alloys (HEAs), as a new class of alloys, have attracted alloy designers and metallurgists due to their superior mechanical properties (e.g., strength and toughness), resistance to oxidation and corrosion, etc. There are so far only limited studies on the welding and weldability of HEAs, mostly on the CoCrFeNiMn alloy and its derivatives, such as CoCrFeNiAlx alloys. Results showed their tendency to microstructural modification and mechanical property changes as a result of different welding processes such as gas tungsten arc welding, electron/laser beam welding and friction stir welding. The microstructure and property changes are also dependent on the types of HEAs. The limited studies so far suggest, in order to support broad materials based on the HEA concept for engineering applications, more extensive weldability assessments and studies on HEAs are needed to cover a wider range of composition in parallel with their property improvement. In addition, focuses of HEA welding studies should expand from laboratory-scale studies to investigation of industry scale parts.