Design principles of low-activation high entropy alloys
Liangzhi Tan, Kawsar Ali, P. S. Ghosh, Ashok Arya, Ying Zhou, Roger Smith, Pooja Goddard, D.J. Patel, Hamed Shahmir, Amy S. Gandy
Abstract
The present study combines density functional theory (DFT) based calculations and experimental techniques to investigate the formation of equiatomic quaternary “low-activation" high entropy alloys (HEAs) for nuclear fission/fusion applications. DFT based techniques are adopted to screen the formation of possible single-phase ternary and quaternary alloys in chemical space consisting of the low-activation elements (Ti, V, Cr, Mn, Fe, Ta and W). The results indicate that TaTiVW and CrFeMnV can be formed in a single body centred cubic phase (BCC). Based on the DFT based screening, HEAs are fabricated by a vacuum arc melting process. Further characterisation by X-ray diffraction, energy dispersive X-Ray analysis, X-ray fluorescence and scanning electron microscopy confirms the formation of TaTiVW in a BCC single phase. Microstructures of CrTiVW and CrTaVW in as-cast conditions, consist of two BCC phases with very similar lattice parameters. CrTaTiW and CrTaTiV showed evidence of C15 Laves formation comprising of TaCr2 and TiV2, respectively.