Effect of Laser Scan Speed on Microstructure and Mircohardness on Titanium Clad Magnesium

Magnesium and its alloys surfaces could be protected by various surface modification techniques. Among them, laser cladding has been identified as a prominent technique. In this present work, Ti6Al4V titanium alloy was clad on pure magnesium by laser cladding and the influence of the laser scan speed on the coating morphology, microstructure and microhardness were investigated. The results revealed that the increasing scan speed above 300 mm/min has resulted in inadequate coating deposition. The Fe2O3Ti secondary phase particle had precipitated at the grain boundaries of the clad material and MgO phase was formed at the interface. The Al12Mg17 phases were present in both clad and heat affected substrate material. The influence of laser scan speed on grain size and their orientation was limited. However, the scan speed influences the intensities of precipitated intermetallic particles. Higher microhardness was observed in the sample processed at 300 mm/min scan due to the presence of higher intensities of intermetallic particles in its clad zones.