Two-step laser cladding of Inconel 625 on copper

Abstract

Copper is widely used in many industrial applications although its poor mechanical properties limit its use. Nevertheless, nickel-based alloys offer high wear resistance that applied on copper as surface coating could overcome this lack. The direct application of coatings with laser technologies on a copper substrate presents difficulties due to the poor absorption of this metal in the usual wavelengths of lasers, and this study is focused precisely on solving them. The results of the two-step laser cladding of Inconel 625 on the copper substrate are analyzed in terms of microstructure, chemical analysis, and hardness. Moreover, the metallurgical bonding of (Cu and Ni) solid solution between the direct laser cladding coating of the Ni alloy and copper is studied as well as the absence of interfacial cracks and pores under specific process parameters. This bond is assured by the high dilution and the presence of 27 wt. % of copper. The second functional Inconel 625 layer shows a dendritic microstructure with a γ-Ni matrix and Mo- and Nb-rich precipitates in the interdendritic regions with no trace of copper.