Laser surface alloying of copper with chromium. II. Improvement in mechanical properties

The present study concerns the scope and extent of improvement in the abrasion and erosion resistance of pure Cu by laser surface alloying (LSA) with Cr using a continuous wave CO2 laser. Following LSA, the alloyed zone (AZ) registers 2-3 times enhancement in microhardness. This increase has been correlated with the microstructure and composition of the AZ. The optimum processing conditions for achieving the desired mechanical properties in the AZ have been summarized in the form of a process optimization diagram. Subsequently, a detailed study concerning wear (both adhesive and abrasive) and erosion resistance has been undertaken. It is found that both adhesive and abrasive wear losses are directly related to the applied load and time. Besides dry adhesive/abrasive wear, LSA seems to markedly improve the erosive wear both at room and elevated temperature. Thus, it is finally concluded that LSA of Cu with Cr may significantly improve the microhardness, wear and erosion resistance of pure Cu.