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对纯镍激光熔凝组织特征及其氧化行为进行研究,对形成机理和氧化动力学作了分析和探讨。结果表明:随着扫描速度的增加,纯镍激光熔凝组织特征依次显示为粗大等轴晶、等轴晶和树枝晶、树枝晶和脆状晶。由于激光高温作用促进了氧分子的电离,裂纹、孔洞等机械破坏的形成以及强烈的熔池对流又加速了氧离子的扩散,因此,激光处理与一般常规处理相比,具有更高的氧化速度。
The characteristics and oxidation behavior of pure nickel laser melted tissue were studied, and the formation mechanism and oxidation kinetics were analyzed and discussed. The results show that with the increase of scanning speed, the laser solidification microstructures show as follows: coarse equiaxed grains, equiaxed grains, dendrites, dendrites and brittle grains. Due to the high temperature of the laser, the formation of mechanical damage such as ionization, cracks and holes in the oxygen molecules and the accelerated convection of the molten pool accelerate the diffusion of oxygen ions. Therefore, the laser treatment has a higher oxidation rate than the conventional treatment .