Laser powder bed fusion additive manufacturing of Ti-coated diamond/ (CoCrNi)82Al9Ti9 composites: Process optimization, microstructure features and wear resistance

Deep drilling faces a series of complex and harsh conditions (i.e., high temperature, high pressure and high hardness crystalline rock), thus putting forward higher requirements for the strength, toughness, and rock crushing ability of deep-hole drill bits. As a result, new drill material composition are required urgently. In this study, we attempted to prepare the Ti-coated diamond (20 vol%)/(CoCrNi)82Al9Ti9 composite by using laser powder bed fusion (LPBF) additive manufacturing technology. The densification behavior, microstructure features and wear properties of the as-fabricated composites were systematically studied. The results showed that the Ti-coated diamond/MEA composite exhibited a relatively narrow LPBF processing window, and the optimized laser energy density was determined to be in a range of 156-233.33 J/mm3 with a combination of low P and low v . Significant diamond graphitization was detected, and the corresponding 'D/'G was increased from 0.67 to 0.77 with the applied v increasing from 400 mm/s to 600 mm/s. Due to the significant diffusion of carbon atoms from the diamond, massive carbide dendrites were also formed within the matrix. Increasing the applied v not only resulted in a significant decrease in the characteristic size and relative content of these carbide dendrite phases, but also caused a decrease in thickness of the interfacial carbide layer. At an optimized v = 400 mm/s, the best wear properties were presented with a steady COF of 0.32 and a low worn volume of 5.17 x 10- 2 mm3.