Microstructure And Properties Of Laser Cladding Al/TiC/Y₂O₃ Composite Coating On AZ91D Magnesium Alloy

Magnesium alloy has a huge application market in space,military,electronic communication,transportation and biomedical because of its advantages such as low density,high specific strength,high rigidity,high shock absorption and easy processing.However,due to the hardness of magnesium alloy,wear resistance and high temperature performance is low,poor corrosion resistance,which to some extent,has restricted the performance advantages of magnesium alloy material play.Laser cladding is an important research direction of laser surface modification technology,which is of great significance to improve the comprehensive performance of magnesium alloy,such as strength,hardness,wear resistance,heat resistance and corrosion resistance.The Al-TiC composite coating and the Al-TiC-Y₂O₃ composite coating were prepared by laser cladding on the surface of AZ91 D magnesium alloy by Nd:YAG solid laser.The mass ratio of Al and TiC was 9:1,6:1 and 3:1,Y₂O₃ additions were 0%,0.6%,0.8%,1.2% and 2.0%,respectively.The microstructures,microhardness and corrosion resistance of the cladding were measured and analyzed by optical microscope,scanning electron microscope,X-ray diffractometer,microhardness tester and electrochemical workstation.The results show that the Al-TiC cladding layer is mainly composed of Ti₃ AlC,Al₃Mg₂,Mg₂Al₃,AlMg,Al,Mg,Ti₆ O and TiC phases,after adding rare earth oxides of Y₂O₃,Al₃ Y and Al₄ MgY Al-TiC-Y₂O₃ of rare earth compounds were formed in the cladding layer.The microhardness of Al-TiC composite coating and Al-TiC-Y₂O₃ composite coating were higher than that of matrix composite.For Al-TiC composite coating,the microhardness of Al:TiC = 9:1 coating was slightly higher than that of Al:TiC = 6:1 and 3:1 cladding layer.For the Al-TiC-Y₂O₃ composite coating,when the cladding layer microhardness of Al:TiC = 3:1 of adding rare earth oxide was higher than the hardness of cladding layer without the addition of Y₂O₃,in a certain proportion,adding rare earth to improve the effect of cladding layer hardness was very obvious.As for corrosion resistance,the self corrosion potential of the matrix was-1.475 V,which is lower than that of Al-TiC composite coating and Al-TiC-Y₂O₃ composite coating,which indicates that the corrosion resistance of the cladding layer was improved.For Al-TiC composite coating,the corrosion resistance of 9:1 coating was better than that of 6:1 and 3:1 cladding layer.For the Al-TiC-Y₂O₃ composite coating,the corrosion resistance of the cladding layer were the best when Al:TiC = 6:1 was added to 2.0%Y₂O₃,and the corrosion resistance of the cladding layer was the best when Al:TiC = 3:1 was added to 0.6%Y₂O₃.