铜合金表面激光熔覆Ni基涂层的组织及界面结构

Microstructure and Interfacial Characteristics of LASER Cladding Ni-based Coating on Copper Alloy

采用预置粉末法,在Cu-0.9Cr-0.26Zr铜合金基体上激光熔覆了Ni基涂层。利用X射线衍射、扫描电镜、能谱仪及透射电镜等研究了Ni基涂层组织、涂层/基体的界面结构和互扩散行为。结果表明,含适量Al的KF-6合金在激光与反应放热耦合作用下形成了与基体润湿良好、冶金结合的界面,熔覆层无缺陷,且组织致密呈细小枝晶状。熔覆层主要由γ-Ni固溶体、AlNi3和Al3Ni5组成,界面区为(Ni,Cu)固溶体。激光非平衡作用下,熔池内溶质再分配,界面附近固相的实际浓度增大,相应界面附近熔体浓度降低,界面区成分过冷而形成层状光亮带。界面区TEM组织大小均匀,晶粒达亚μm级,(Ni,Cu)固溶体是良好冶金结合界面的基础。

The Ni-based coating containing A1 was deposited on Cr-Zr-Cu alloy by Nd. YAG laser cladding. Interfacial characteristics and inter-diffusion behavior at the coating/copper substrate interface of the coated Cr-Zr-Cu alloy were investigated by X-ray diffraction （XRD） and scanning electron microscopy （SEM） equipped with X-ray energy dispersive microanalysis （EDX）, as well as transmission electron microscopy （TEM）. The results indicate that the Ni-based alloy coating exhibits metallurgical bonding with copper substrate as a result of chemical heat release between Ni and A1 induced by laser. The absence of defects in cladding layer with fine and compact structure can be observed. The microstructure of the coating is composed of γ-Ni,A1Ni3 and A13Nis. （Ni, Cu） solid solution phase is formed at interface, which is responsible for metallurgical bonding by diffusion between Ni-based coating and copper substrate. During the rapid solidification process of molten pool, actual concentration of solid phase near the interface is increased and actual concentration of liquid phase near the interface is decreased as a result of redistribution fo the solute in the molten pool in unequilibrium effects of the laser.