钛合金表面难熔陶瓷激光熔覆层的制备及性能

Preparation and properties of refractory ceramic laser cladding layer on titanium alloy surface

基于难熔合金的设计理论,利用激光熔覆技术,以Ti-6Al-4V为基粉,HfC、ZrC、TaC和NbC这4种粉末为增强相,使用优化后的激光加工工艺参数,在钛合金板上制备了钛基金属-难熔陶瓷复合熔覆层,并通过实验对激光熔覆层的组织和显微硬度进行了分析。结果表明,熔覆层截面组织以不同形态的TiC晶体为主,存在等轴α-Ti和β-Ti组织;加入的陶瓷相颗粒弥散分布在熔覆层中,组织晶粒得到了细化,其细化程度随着过渡金属元素加入比例的增大而增大;添加陶瓷粉末熔覆层的硬度明显高于未加陶瓷粉末的熔覆层显微硬度;随着陶瓷粉末加入比例的增大,硬度逐渐增大,当陶瓷相含量为10%时,熔覆层的硬度最高为675 HV,比基材硬度提高了1.7~2.0倍。

Based on the design theory of refractory alloys,using laser cladding technology,taking Ti-6Al-4V as the base powder,and four kinds of powder HfC,ZrC,TaC,NbC as the reinforcing phase,the composite cladding layer was fabricated on titanium alloy plate by using optimized laser processing parameters.The microstructure and microhardness of laser cladding layer were analyzed by experiments.The results show that TiC crystals with different morphologies are the main microstructure in the cross section of the cladding layer,and there are equiaxedα-Ti andβ-Ti microstructures.The ceramic phase particles are diffusively distributed in the cladding layer,and the microstructure grains are refined,and the degree of refinement increases with the increase of the proportion of transition metal elements.The hardness of the cladding layer with added ceramic powder is significantly higher than that of the cladding layer without added ceramic powder.As the proportion of ceramic powder added increases,the hardness gradually increases,when the ceramic phase content is 10%,the maximum hardness of the cladding layer is 675 HV,which is 1.7-2.0 times higher than that of the base material.