A novel and sustainable method to develop non-equiatomic CoCrFeNiMox
high entropy alloys via spark plasma sintering using commercial commodity
powders and evaluation of its mechanical behaviour
A novel approach to developing high entropy alloys (HEAs) using spark plasma
sintering (SPS) was explored in this work where a mix of commercial commodity
powders like Ni625, CoCrF75, and 316L was used instead of pre-alloyed powders
avoiding the expensive pre-alloying steps like mechanical alloying or gas
atomizing. Three non-equiatomic HEAs, based on Co, Cr, Fe, Ni, and Mo were
designed and developed by blending the powders which were sintered via SPS and
resulted in a single FCC phase after homogenization. The HEAs were
microstructurally and mechanically characterized with tensile and hot
compression tests up to a temperature of 750oC showing excellent properties.
The maximum room temperature tensile strength and ductility demonstrated was
712 MPa and 62% respectively, by the alloy Co23.28Cr28.57Fe25.03Ni21.01Mo2.1.
Moreover, the same alloy exhibited a compression strength greater than 640 MPa
with a ductility above 45% at a temperature of 750oC. Also, this study paves
the way for a novel fabrication route that offers more flexibility to develop
new HEAs cost-effectively and efficiently which is crucial for the discovery of
new materials over high-throughput techniques. Using such commodity alloys also
opens the possibility of developing ingot casting from recycled scraps avoiding
the direct use of critical metals