Ultra-high strength of additively manufactured CoCrNi medium entropy alloy with high-fraction TiC

Abstract

In this work, the novel CoCrNi composite with as high fraction as 5 wt% TiC reinforcements were additively manufactured (AMed) by laser powder bed fusion (LPBF) of blended powders of nano-C particles, spherical micro-Ti powders and spherical CoCrNi powders, instead of blended powders of nano-TiC and CoCrNi powders. This method resulted in fully melting of C and Ti elements during laser fusion and subsequent precipitation of nano-TiC during solidification. The agglomeration of nano-TiC in the matrix is reduced by this method, resulting in an 1800 MPa ultrahigh strength, simultaneously maintaining a considerable elongation of 12 %. Rise in the fractions of TiC from 0 to 5 wt% reduces intensity of the texture and grain size in the matrix and convert the strong 〈101〉 texture to relative weak 〈100〉 texture along building direction (BD).