Gd元素对激光熔覆镁合金涂层组织和性能的影响

发布时间：2018-06-29 01:48

本文选题：激光技术 + 激光熔覆　；参考：《中国激光》2015年03期

【摘要】：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 grain boundary of ZM5 magnesium alloy laser cladding coating is easy to precipitate banded 尾 -Mg17Al12 phase, which results in the decrease of the tensile properties of the coating. The effect of Gd element on the microstructure and properties of laser cladding Mg-Al-Gd coating on ZM5 cast magnesium alloy was studied by adding rare earth Gd element to the surface of ZM5 magnesium alloy. The results show that Al _ 2Gd particle phase is formed in the cladding coating with 5.0% Gd by mass fraction, and Mg17Al12 eutectic phase at grain boundary is refined into spherical particles and short rod shape, and the amount of precipitation decreases significantly, and the high temperature tensile strength of the coating containing Gd magnesium alloy is decreased. The yield strength and yield strength ratio are improved greatly, and the morphology of tensile fracture surface of ZM5 magnesium alloy laser cladding coating is found to have local grain boundary melting characteristics, and the tensile fracture surface of laser cladding coating of ZM5 magnesium alloy is characterized by local grain boundary melting. However, no grain boundary melting was observed on the fracture surface of laser cladding coating of magnesium alloy with Gd element, which indicates that Gd element can inhibit the precipitation of eutectic phase at low melting point Mg17Al12 between dendrites and strengthen grain boundary, thus improving the high temperature tensile properties of the cladding coating.
【作者单位】：上海交通大学上海市激光制造与材料改性重点实验室;
【分类号】：TG174.4

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