Gd元素对激光熔覆镁合金涂层组织和性能的影响

ZM5镁合金激光熔覆涂层的晶界易析出条带状β -Mg17Al12相，导致涂层的拉伸性能下降。通过添加稀土Gd元素，在ZM5 铸造镁合金表面激光熔覆Mg-Al-Gd 涂层，研究Gd 元素对ZM5 镁合金激光熔覆涂层组织和性能的影响。结果表明，添加质量分数为5.0%的Gd元素的熔覆涂层中生成了Al2Gd颗粒相，晶界处Mg17Al12共晶相细化成球形颗粒和短棒状，且析出量显著减少；含Gd镁合金熔覆涂层高温抗拉强度、屈服强度以及屈强比均有较大提高；高温拉伸断口形貌分析发现，ZM5 镁合金激光熔覆涂层拉伸断口出现局部的晶界熔化特征，而添加Gd 元素的镁合金激光熔覆涂层断口未观察到晶界熔化，这表明Gd元素能抑制枝晶间低熔点Mg17Al12共晶相析出而强化晶界，从而可提高熔覆涂层的高温拉伸性能。

Abstract

The mechanical properties of ZM5 magnesium laser clad coatings are weaken by the lamellar β -Mg17Al12 phases on grain boundaries. The Mg-Al-Gd coatings on cast magnesium alloy are fabricated by laser cladding. The effects of Gd addition on the microstructures and tensile behaviors of coatings have been investigated. The results indicate that the Gd addition led to the formation of a cubic Al2Gd phase as well as suppresses the precipitation of the eutectic Mg17Al12 phase. The laser clad coating with 5.0% mass fraction Gd presents higher ultimate tensile strength and yield strength than that without Gd element at both room temperature and high temperature. The enhancement of heat resistant capacities is chiefly attributed to the existence of thermally stable Al2Gd particles, which prevents tiny liquation of eutectic phases along the grain boundaries and makes great contributions on maintaining high yield ratio during high-temperature deformation.

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陈宏, 李铸国, 姚成武, 吴毅雄. Gd元素对激光熔覆镁合金涂层组织和性能的影响[J]. 中国激光, 2015, 42(3): 0306002. Chen Hong, Li Zhuguo, Yao Chengwu, Wu Yixiong. Effect of Gd on Microstructure and Properties of Laser Clad Magnesium Coatings[J]. Chinese Journal of Lasers, 2015, 42(3): 0306002.

Gd元素对激光熔覆镁合金涂层组织和性能的影响

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