纳米La_2O_3含量对NiCrCoAlY熔覆涂层组织及硬度的影响

Influence of different contents of nano-La_2O_3 particles on microstructure and hardness of NiCoCrAlY coatings

基于激光熔覆技术在TC4合金表面制备NiCoCrAlY熔覆涂层,考察纳米稀土La2O3含量对熔覆涂层质量的影响。利用金相显微镜、扫描电镜以及显微硬度计对添加稀土La2O3含量分别为0,1%,2%和3%的涂层的微观形貌、组织及硬度进行观察和研究。结果表明,随着纳米稀土La2O3含量的增加,熔覆层的稀释率逐渐降低,抑制了熔覆层中柱状晶的生长,加速了枝状晶的形成,且枝状晶的分支加剧,二次枝状晶的间距减小,使熔覆层的晶粒得到细化,并且出现花朵状。添加纳米稀土La2O3的熔覆层硬度相对未添加的都较高,但随着其含量的增加呈现逐渐下降趋势。

NiCoCrAlY laser cladding coatings were prepared on TC4 alloy by laser cladding technology.Influence of different contents of nano-La2 O 3 particles on quality of coatings was investigated.Morphology,microstructure and micro-hardness of the laser cladding coatings with 0,1%,2% and 3% nano-La2 O 3 were investigated by means of metallographic microscope,SEM and micro-hardness tester.The result indicated that with the content of nano-La2 O 3 increasing,dilution rate of cladding layers decreased gradually.The growth of dendritic crystal was inhibited,and the formation of dendritic crystal accelerated.Branch of dendritic crystal was aggravated and the space of with secondary dendritic crystal was decreased,which caused that the grain was refined, and the flower-like grain appeared in the cladding coating.The micro-hardness of cladding layers with nano-La2 O 3 was higher than without nano-La2 O 3 ,and the micro-hardness of cladding layers decreased gradually with the increase of content of nano-La2 O 3 .