Interfacial Compatibility for Laser Melting Deposition of CoCrNiCu Medium-Entropy Alloy on 316L Austenitic Stainless Steel Surface

YH Yu and Y Xie and P Chen and HK Dong and JX Hou and ZX Xia, ACTA METALLURGICA SINICA, 60, 1213-1228 (2024).

Dissimilar materials can achieve multifunction and multiperformance coupling and have broad development prospects in areas, such as aerospace, energy, automotive, and biomedicine. The properties of dissimilar materials can be improved by enhancing the compatibility of the heterogeneous interface. Herein, a laser melting deposition experiment of CoCrNiCu medium-entropy alloy (MEA) on the surface of 316L stainless steel was carried out. The microstructure morphology and interface charac-teristics of the dissimilar materials were characterized using SEM, STEM, EBSD, and transmission Kiku-chi diffraction (TKD). The interfacial mechanical properties of the dissimilar materials were tested. The methods for promoting the bonding strength of dissimilar materials were then proposed by systematical-ly exploring the interfacial compatibility of the microstructure and crystallography. The results show that a total solution transition zone of CoCrNiCuFe, a high-entropy alloy, was formed at the interface be- tween CoCrNiCu MEA and 316L stainless steel. The shear strength of the dissimilar material can reach 324 MPa. Through the synergistic effect of austenite stability reduction caused by C interfacial partition-ing and the plastic deformation induced by residual stress, some austenite grains of 316L stainless steel near the interface of the dissimilar materials undergo strain-induced martensitic transformation. This can promote the transformation-induced plasticity (TRIP) effect to improve the strength and ductility of the dis-similar materials while reducing interface matching. Therefore, as for the dissimilar materials with small physical discrepancies, single-phase matching with the same crystal structure should be maintained to in-crease the interfacial bonding strength by improving the interfacial crystallography compatibility. The TRIP effect can be used to design a duplex structure to improve the process of coordinated deformation for dis-similar materials with large physical discrepancies.

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