Designing co-reinforced in-situ (Cr3C2(w) + Cr2O3(p))/CoCrFeNi composite with excellent strengthening efficiency

A process is developed for fabricating in-situ CoCrFeNi matrix composite co-reinforced with Cr3C2 whiskers and Cr2O3 nanoparticles. Initially, mechanical alloying of the powder was carried out to obtain powder containing laminates of FCC and thin Cr rich layers along with carbon dispersed at the laminate interfaces. The powder was then reaction sintered as the Cr layers reacted with carbon and transformed into Cr3C2 phase. Concomitantly, a uniform precipitation of Cr2O3 nanoparticles took place across the microstructure. The designed microstructure exhibited excellent reinforcement efficiency and a yield strength of over 1 GPa along with elongation of 12% was achieved. According to the calculation based on strengthening mechanism models, the reinforcements were estimated to be responsible for a more than 100% increase in matrix yield strength.