Investigation of the Implementation of Laser Surface Alloying of Cu with Cr–WC

Abstract

This paper presents research on the microstructure and mechanical properties of an alloyed composite copper (Cu) surface layer, reinforced with a mixture of chromium–tungsten carbide (Cr–WC) powders. Copper alloying was performed using a high-power diode laser (HPDL). In the tests, three mixtures of powders with different percentage contents (75%Cr 25%WC, 50%Cr 50%WC, 25%Cr 75%WC) were injected into the melting pool during the laser surface alloying process. Microstructural evolution and the properties of the surface layer of copper after laser alloying were investigated. Structural investigations were performed using light microscopy, scanning and transmission electron microscopy (SEM, TEM) and X-ray diffraction (XRD). Microhardness and wear resistance of the modified surface layer were examined as well. After laser treatment the applied powders appear as uniformly distributed particles in the alloyed zone as well as nanoscale precipitates in the Cu matrix. Several types of precipitate characteristics, in terms of morphology, structure and chemical composition, were observed. Laser alloying of the surface layer modified the microstructure, which resulted in an increase in the hardness of the surface layers compared to the base material.