镍基合金激光熔覆成形的快速凝固组织特征研究

The Rapid Solidification Characteristics of Ni-based Alloy Fabricated by Laser Cladding Forming

利用激光熔覆成形技术制备出平整无变形的镍基合金样品,对显微组织中的层生长模式、晶粒生长模式,重熔情况以及一些缺陷等凝固组织的特征进行了详细分析。结果表明层的形状主要取决于激光功率和粉末熔化状况,显微组织以细长的柱状晶为主。为使层与层之间具有良好的冶金结合,每层的重熔区域必须保持一定的厚度。激光功率过低时组织中易形成气孔,而成形件的卷曲现象可以通过预热等方法加以解决。

Laser cladding forming （CLF） has been used to build up solid samples from the Ni-based powders. The appearances of these samples are smooth and no apparent shape distortion. The solidification characteristics including layer growth mode, grain growth mode, remelting condition, defects, etc. , were analyzed in detail. The results show that the layer profile was determined by laser power and the melted powder ratio. The mierostrueture mainly consists of fine columnar grains. A certain remelted thickness is necessary to keep metallurgical bonding between layers. Pores appeared in the structure when the input power was insufficient while curling distortion can be efficiently eliminated by pre-heating substrate.