钛合金表面激光熔覆Ni基梯度涂层的研究

Microstructure and Microhardness of Laser Cladding Nickel-Based Gradient Coating on Ti6Al4V Alloy

为了改善Ti6Al4V钛合金表面耐磨性能和抗高温氧化性能,采用CO2激光在Ti6Al4V钛合金表面进行激光熔覆Ni基梯度涂层试验。利用扫描电镜和显微硬度计等手段分析了熔覆层组织,测试了基体和熔覆层的显微硬度。结果表明,采用适当的工艺参数,可以在钛合金表面获得连续、均匀、无裂纹和气孔的熔覆层。熔覆层组织由树枝晶和晶间共晶组织构成,并与基体形成牢固的冶金结合。由基体到表面,显微硬度过渡平稳,呈明显梯度渐变特征。

CO_2 laser was performed to prepare laser cladding Ni-based gradient coating on the surface of Ti6Al4V alloy so as to improve the wear resistance and high-temperature oxidation resistance of the alloy. The microstructure and microhardness of the laser cladding Ni-based gradient coating were analyzed using a scanning electron microscope and microhardness meter, respectively, using the Ti6Al4V substrate as the reference. As a result, it was feasible to prepare continuous and homogeneous Ni-based coating free of pores and cracks by optimizing the laser cladding parameters. The resulting Ni-based laser cladding coating was composed of dendrite and intergranular eutectic and had good metallurgical bonding to the substrate. Moreover, the Ni-based coating had gradient microhardness, with the maicrohardness to gradually vary from the surface to the Ti-alloy substrate.