TiC含量对TC4合金激光熔覆层组织和性能的影响

采用激光熔覆工艺在TC4钛合金基体表面制备了添加不同质量分数(0%、2%、4%、6%)TiC的Ni60A复合熔覆层,通过光学显微镜、显微硬度计、X射线衍射仪、摩擦磨损机分析了不同TiC含量对熔覆层组织及性能的影响。结果表明:未添加TiC的熔覆层组织以树枝晶为主,添加TiC后出现了花瓣状物相;XRD分析发现熔覆层中出现了AlCCr₂、Al_0.24B_0.01Ni_0.75等硬质增强相,这些能够显著提高熔覆层的硬度。显微硬度及摩擦磨损试验结果表明,添加TiC的熔覆层平均硬度均较基体硬度有大幅提高,摩擦因数显著降低,且随TiC含量的增加,熔覆层硬度先增加后降低,摩擦因数先降低后增加,4%TiC熔覆层的硬度最大,相比基体提高了213.3%,摩擦因数最小,为0.309 774。

Effect of TiC content on microstructure and properties of laser clad layer on TC4 alloy

Ni60A and (2%, 4%, 6%)TiC+Ni60A composite coatings were prepared on the surface of TC4 titanium alloy by laser cladding process. The influence of different TiC mass fractions on the microstructure and properties of the clad layer were analyzed by metallographic microscope, microhardness tester, X-ray diffractometer, and friction-wear machine. The results show that the microstructure of the clad layer without TiC is dominated by dendrites, and the TiC addition leads to the appearance of petal phase. The XRD analysis shows that hard reinforcing phases AlCCr₂, Al_0.24B_0.01Ni_0.75 appear in the clad layer, which can significantly increase the hardness of the clad layer. The results of microhardness and friction and wear tests show that the average hardness of the clad layer with TiC is significantly higher than that of the matrix, and the friction coefficient is significantly reduced. With the increase of TiC content, the hardness of the clad layer increases first and then decreases, while the friction coefficient decreases first and then increases. The hardness of the clad layer with 4% TiC is the highest, which is 213.3% higher than that of the matrix, and the friction coefficient is the lowest, which is 0.309 774.