Effects of pre-heating induced interfacial diffusion on microstructure and related mechanical properties of direct laser metal deposited Inconel 625 superalloy on a Cu-Cr-Zr substrate

Copper-based alloys possess outstanding thermal and electrical conductivity, making them popular in the electronic and aerospace industries. However, its low hardness makes it vulnerable to failure in harsh service environments, which require surface coating. By using the direct laser metal deposition method to coat harder alloys on the surface of Cu alloys, the challenge of this copper alloy's high laser reflectivity was noted. To solve this problem, both substrate preheating and high-power LMD methods were employed, which established an excellent metallurgical bonding between the coating and substrate with a 2 μm diffusion layer and enhanced the Cu-Cr-Zr substrate's hardness and wear resistance. Due to the presence of copper elements in the fusion zone, the constituent supercooling zone is increased, resulting in a finer columnar crystal structure in the fusion zone. Such elements exchange process during LMD produces will also improve the mechanical properties of the Cu-Cr-Zr substrate by solid solution strengthening. •Novel LMD Strategy for tightly connected superalloy coatings on copper substrate.•Pre-heating increases the strength of interfacial region by enhanced diffusion.•Constitutional supercooling of Cr and Zr elements increases interfacial strength.•Diffused Cu is homogeneously distributed in the coating and causes grain refinement.