Effect of Y 2 O 3 Addition on Microstructure and Properties of Laser Cladded Al-Si Coatings on AZ91D Magnesium Alloy.

The effect of YO addition on the microstructure and properties of the laser cladded Al-Si alloy coating on the surface of AZ91D magnesium alloy was investigated in this study. The experimental results showed that the Al-Si + YO cladding layers contained α-Mg, MgSi, AlMgY and a small amount of AlMg phases. The coarse dendrites, reticulated eutectic structures and massive phases in the coatings tended to be refined and gradually uniformly distributed with the increased amount of YO. The introduction of YO into the cladding layer favored the improvement of microhardness and wear resistance due to the grain refinement strengthening and dispersion strengthening. The addition of YO also promoted the reduction of localized corrosion sites and made the corrosion surface smoother, implying that the corrosion resistance of the YO-modified coatings was better than that of the unmodified cladding layer.