In Situ Formation of Intermetallic Compound Bonding by Laser Cladding Al2o3 to Enhance the Corrosion Resistance of Az31 Magnesium Alloy
D. Xiang, S. Li, L-H. Yi, T-F. Liu, J. Liu, C-M. Yang and L-H. Zhou
The AZ31 magnesium alloy attracts lots of interests owing to high specific strength, low specific density. But, high chemical reactivity and low resistance to corrosion limit its applications in automotive lightweight application. In this study Mg-Al intermetallic compounds formed between an Al2O3 coating and the AZ31 magnesium alloy substrate because of the lower melting point of Mg and its high diffusion rate, chemical reactivity, which produced a reliable metallurgical bonding. The cross-section could be divided into the cladding zone, interfacial zone, and substrate based on the microstructural difference. Electrochemical tests showed that Al2O3 laser cladding of the AZ31 magnesium alloy resulted in a higher corrosion potential and a lower current density than as-received samples. Immersion tests in 3.5 wt.% NaCl solution also showed similar trends. The Al2O3 laser cladding of the AZ31 magnesium alloy exhibited higher hardness and wear resistance over as-received samples owing to wear resistance ability of Al2O3 hard phase.
Keywords: Fibre laser, magnesium alloy, Al2O3 coating, intermetallic compounds, laser cladding, corrosion resistance, wear resistance