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采用激光熔覆方法制备了Ni-Sn共晶合金熔覆层,通过对不同扫描速度下熔覆层的组织特征进行分析,发现熔覆层组织主要由α-Ni+Ni-Sn层片共晶组成,层片间距相比基材明显细化,并且在熔覆层与基材界面处,共晶层片基本沿熔覆层沉积方向外延生长,随着远离基材,层片共晶生长方向逐渐向激光扫描方向偏转,在垂直激光扫描方向的熔覆层横截面呈现出类等轴的共晶团组织。随着扫描速度的增加,熔覆层中的带状组织和顶部的少量非规则共晶团逐渐消失,共晶层片间距减小。用描述快速共晶生长的TMK模型对熔覆层底部的共晶层片间距随激光扫描速度的变化规律进行了分析,实验结果与理论模型基本吻合。
The cladding layer of Ni-Sn eutectic alloy was prepared by laser cladding. The microstructure of the cladding layer was analyzed by scanning electron microscopy (SEM). The microstructure of the cladding layer was mainly composed of α-Ni + Ni-Sn And the interlayer spacing is obviously thinner than that of the substrate. At the interface between the cladding layer and the substrate, the eutectic layer epitaxially grows along the deposition direction of the cladding layer. With the distance from the substrate, the eutectic layer growth direction Gradually deflected to the direction of laser scanning, the cross-section of cladding layer in the direction of vertical laser scanning showed equiaxed eutectic texture. With the increase of scanning speed, a small amount of irregular eutectic clusters in the cladding layer and the top gradually disappear, and the eutectic layer spacing decreases. The TMK model, which describes the rapid eutectic growth, was used to analyze the variation of eutectic layer spacing at the bottom of cladding layer with the laser scanning speed. The experimental results are in good agreement with the theoretical model.