Laser surface engineering of copper with chromium for enhanced wear resistance

• Published in: Scripta materialia 1996-08, Vol.35 (3), p.405-410
• Main Authors: Manna, I., Majumdar, J.Dutta, Chatterjee, U.K., Nath, A.K.
• Format: Article
• Language: English
• Subjects: Applied sciences; Exact sciences and technology; Metallic coatings; Metals. Metallurgy; Production techniques; Surface treatment
• ISSN: 1359-6462; 1872-8456
• DOI: 10.1016/1359-6462(96)00149-2

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 Cu is known to significantly improve its wear resistance without deteriorating its thermal and electrical conductivity. However, the insigificant solid solubility limit of Cr in Cu (maximum 0.89 at.% at 1350K) 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. Hirose and Kobayashi have recently attempted surface alloying of Cu with Cr by LSE and achieved an increase in hardness of the AZ (containing approx20 wt.% or 16 at.% Cr) than that of the substrate, presumably due to dispersion strengthening offered by the chromium-precipitates. However, the consequent improvement in wear resistance was not investigated in that study. Furthermore, the data presented by them were measured from isolated laser alloying tracks instead of that obtained from a surface lased with a suitable surface integration. In the present study, we will report a similar attempt of LSE of Cu with Cr adopting a different technique of pre-deposition of Cr, and correlate the observed improvement in microhardness and wear resistance with the microstructure and composition of the AZ.