关键词: 激光熔覆, 镁合金, 稀土氧化物, Al-Cu涂层

Abstract: Al-Cu coatings with different additions of La2O3 were cladded on AZ91D magnesium alloys using Nd: YAG laser. Surface morphology, microstructure and phase structure of the cladding layers were investigated with the aid of scanning electron microscope, energy disperse spectroscopy and X-ray diffraction technology. The results show that the grain sizes of the coatings may be refined with the additions of La2O3 in Al-Cu powders and the properties of the cladding layers are improved. Intermetallic compounds Mg17La2 and LaAl3 are generated in the cladding layers. Micro-hardness distributions and friction coefficients of the cladding layers were tested by micro-hardness tester and sliding wear testing machine. Al-Cu coatings with the addition of 1.2% La2O3 have the dramatically refined grains and the highest micro-hardness, which leads to the excellent performance of the cladding layers. The average friction coefficients of the cladding layers with La2O3 additions are lower than that without La2O3 additions or magnesium matrix. Obviously, the friction coefficients of cladding layers may be reduced by the additions of La2O3, thus the wear resistance of the cladding layers is improved.

Key words: laser cladding, magnesium alloy, rare earth, Al-Cu coating