Accelerated screening of Tax(CoCrFeMnNi)1-x and Nbx(CoCrFeMnNi)1-x high-entropy alloys

High entropy alloys are a promising group of materials with seemingly limitless and unexplored composition spaces, capable of producing extraordinary physical/mechanical properties that exceed those of conventional materials. Utilizing an additive manufacturing enabled high throughput materials discovery framework, Ta and Nb graded additions to CoCrFeMnNi are explored. Compact metallurgical Ta,Nbx(CoCrFeMnNi)1-x specimens spanning x = 0 - 100 at.% were fabricated by powder based directed energy deposition. Microstructure evolution as a function of specific Ta,Nbx(CoCrFeMnNi)1-x compositions is investigated through a combination of XRD/XRF and SEM-EDS/EBSD. Microhardness measurements were also performed to rapidly establish base-line structure-property relationships. Results revealed that eutectic microstructures were largely suppressed throughout the explored composition ranges resulting in limited ductility and extraordinary hardness.