纯金属Ni在激光熔凝处理后的缺陷

Defects of laser remelting on pure metal Ni surface

本文采用HG-2型高功率CW CO_2激光器对有色金属Ni进行了熔凝处理。实验材料是纯度为99.9％的电解Ni。实验结果表明纯Ni的激光熔凝组织特征明显有别于Fe及其合金的激光熔凝组织、纯镍经激光熔凝处理后,其熔化区内存在大量的各种缺陷。这些缺陷包括激光熔化区与其基体的严重分层;熔凝区内存在大量球形气泡和显微空隙;同时,熔化金属被严重氧化,经x衍射分析判明这些氧化产物主要是NiO和Ni_3N。本文深入探讨了形成这些缺陷的原因。

In this paper, nonferrous metal Ni remelted by a model HG-2 high power CW CO2 laser is examined by optical microscopy and electron microscopy. The experimental material is high purity Ni(99.9%wt).The studied results show that the feature of remeking structure for pure metal nickel is obviously different from the one for pure iron and its alloy. After nonferrous metal nickel is remelted by laser, many various defects exist in its melted zone. These defects include severe separation between laser remelting zone and its matrix,many globular bubbles and microscopical cavities in remelting zone,and severe oxidation of molten metal. X ray diffraction analysis ascertains that the oxide products are mainly NiO and Ni3N. Finally, the causes resulting in these defects are forward probed into.