Laser surface engineering of copper with chromium for enhanced wear resistance

Pure copper is extensively used as electrical and thermal conductors in electromechanical and thermal appliances/machines. However, poor resistance to wear is a serious impediment against its use as components subjected to abrasion and/or erosion. Chromium as an alloying element in copper is known to significantly improve its wear resistance without deteriorating its thermal and electrical conductivity. However, the insignificant solid solubility limit of chromium in copper (maximum 0.89 at% at 1,350 K) restricts the scope of solid solution or precipitation strengthening in this system. Laser surface engineering (LSE) involves rapid melting of a deposit and a part of the underlying substrate followed by instantaneous intermixing and solidification of the melt pool on top of the solid substrate to form an alloyed zone (AZ) enabling a significant improvement of the surface dependent properties of interest. The extreme rate of quenching in LSE is capable of extending the equilibrium solubility limit. In the present study, the authors report an attempt of LSE of copper with chromium adopting a different technique of pre-deposition of chromium, and correlate the observed improvement in microhardness and wear resistance with the microstructure and composition of the AZ.

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