纳米Al_2O_3/Ni基合金复合材料激光熔覆层组织  

Al_2O_3 Nanocrystalline/Ni-Based Alloy Composite Coatings Produced by Laser Cladding

作　　者：李明喜[1] 何宜柱[1] 孙国雄[2] 

机构地区：[1]安徽工业大学激光加工研究中心,安徽马鞍山243002 [2]东南大学材料科学与工程系,江苏南京210096

出　　处：《中国激光》2004年第9期1149-1152,共4页Chinese Journal of Lasers

基　　金：安徽省科技厅重点科研项目 (0 4 0 2 2 0 0 4 )资助课题。

摘　　要：采用横流 5 k W CO2 激光 ,在 Ni基高温合金表面制备了纳米 Al2 O3/ Ni基合金复合材料激光熔覆层。利用光学显微镜、扫描电镜 (SEM)及附件 (EDS)分析了熔覆层的快速凝固组织、成分及纳米颗粒的分布。结果表明 ,未加纳米 Al2 O3时界面区为垂直于界面、定向生长的柱状树枝晶组织 ;加入纳米 Al2 O3后 ,熔池凝固结晶组织形态发生变化 ,由细长的柱状树枝晶逐步过渡为较短的树枝晶 ;当 Al2 O3的加入量为 1%时 ,熔覆层与基体的界面区不出现定向生长 ,整个断面呈现等轴枝晶组织 ;纳米 Al2 O3促进固液界面前沿形核 ,纳米 Al2 O3附着在晶体生长的前沿 ,阻碍晶体的长大 ,凝固组织得到显著细化 ;纳米 Al2 O3颗粒抑制了熔覆层裂纹的形成。Composite coatings of Al_2O_3 nanocrystalline/Ni-based powder produced by transverse flow CO_2 laser on Ni-based superalloy were introduced. With Olympus Pme-3 type optical microscope, Philip-XL 30 type scanning electronic microscope (SEM) and energy dispersive X-ray spectroscopy (EDS), the microstructure, chemical composition and distribution of nano particles of the cross-sections of the coatings were analyzed. The results showed that columnar dendrite grew perpendicularly to the interface without nano Al_2O_3 particles. And the growth morphologies of dendrite transformed from long columnar to short form by adding nano additives. Non-directional dendrite growth at the interface and equaxied dendrite across the section of the clad appeared with the additive amount of Al_2O_3 particles to 1%. The solidified microstructure was greatly refined because the nano Al_2O_3 accelerated nucleation ahead of the advancing interface of solid/liquid and held back crystal growth by its concentration. Nano particles prevented the formation of cracks in the coatings.

关 键 词：激光技术 激光熔覆 纳米AL2O3 组织 

分 类 号：TG156.99[金属学及工艺—热处理]