La2O3含量对激光熔覆TiB/Ti涂层显微结构的影响

目的 改善钛合金表面激光熔覆复合涂层的组织结构,提高钛合金的硬度,使其在相应领域得到更广泛的应用.方法 采用激光熔覆快速非平衡合成方法 制备原位反应合成L2O3-TiB增强钛基复合涂层.用L2O3、Ti和B的混合粉末在Ti-6Al-4V基体表面激光熔覆制备L2O3-TiB/Ti复合涂层,并对其进行XRD物相分析、SEM显微结构观察及显微硬度分析.结果 添加不同含量的L2O3的激光熔覆钛合金复合涂层均与基体较好的结合,涂层中均只有α-Ti和TiB两种物相.随L2O3含量的增加,激光熔覆复合涂层中的增强相TiB的形貌越均匀细小,添加不同含量的L2O3的激光熔覆复合涂层的硬度值约为基体材料的2~3倍,添加质量分数为3%的L2O3的激光熔覆复合涂层硬度最高,其显微硬度值大约为1300HV.结论 添加稀土氧化物L2O3后制备的激光熔覆钛合金复合涂层与基体结合良好,稀土元素的添加使涂层组织细化,硬度得到了明显提高.

Effect of La2O3 Content on Microstructure of the TiB / Ti Composite Coatings Prepared by Laser Cladding

Objective To improve the microhardness and microstructure of composite coatings on titanium alloys prepared by la-ser cladding, in order to enable its wide application in corresponding fields. Methods In-situ reaction synthesized L2O3-TiB rein-forced titanium matrix composites were fabricated using rapid non-equilibrium synthesis techniques of laser cladding. L2O3-TiB/Ti composite coating was fabricated on Ti-6Al-4V surface using L2O3 , Ti and B powder mixture by laser cladding. XRD spectrum, SEM morphology observation and Hardness test of the in situ synthesized Y2O3-TiB/Ti composite coatings were investigated. Results The coatings containing different amounts of L2 O3 were well bonded with the substrate, and there were only α-Ti and TiB phases in the coatings. With the increase of La2 O3 content, the TiB morphology became more uniform and the grain size became fi-ner in the composite coatings. The microhardness values of the composite coatings prepared by laser cladding were 2~3 times high-er than that of the substrate material. The composite coatings with 3wt.% L2O3 content had the highest hardness of about 1300HV.Conclusion The laser cladding titanium alloy composite coatings bonded well with the substrate, and the addition of L2 O3 powder could improve the microhardness of composite coatings, and fine-grained matrix microstructure was formed in the composite coatings.