【摘要】 利用预置涂层法对三种不同成分的合金粉（Ni60A+10,15.20wt%（Ti+C））在45号钢表面进行了一系列激光表面熔覆实验。实验结果表明:利用预置涂层激光表面熔覆技术,可以在碳钢表面直接原位合成TiC颗粒增强的Ni基合金复合涂层,TiC颗粒在激光重熔过程中由石墨和钛原位反应而成。涂层与基体呈良好的冶金结合,涂层宏观质量完好,无裂纹和气孔等缺陷。涂层组织呈典型的外延生长特征,由r—奥氏体、CrB、、M₂₃C₆和TiC等相组成。原位形成的TiC颗粒与基体界面洁净,无任何附着物存在、熔覆层内TiC颗粒呈梯度分布。熔覆层内增强颗粒的数量和尺寸随涂层中添加（TiC）量的增加而增加。涂层显微硬度呈梯度分布,最大可达HV_0.2850,约为基材显微硬度的3.5倍。更多还原

【Abstract】 A composite coating with TiC particles of various shapes and sizes embedded in nickel based alloy has been in - situ synthesized by laser melting a precursor mixture of nickel based alloy powder, graphite and titanium powders using a 3 kW continuous wave CO2 laser. The experiment result showed that the coating epitaxially grew from the substrate with excellent bonding between the coating and the carbon steel substrate was ensured by the strong metallurgical interface. The coating is uniform, continuous and free of pores and cracks, and about 0. 6mm thick. The microstructure of the coating is mainly composed of γ-Ni dendrite, a small amount of CrB and M23C6, and dispersed TiC particles. The volume fraction of TiC particles increase with increasing of volume fraction of Ti and C. The microhardness gradually increased from the bottom to the top of the coating layer, the maximum is HV0.2840, about 3. 5 times larger than that of the steel substrate.更多还原