激光熔覆制备原位颗粒增强金属基复合表层组织性能的研究  

The Investigation on the Microstructure and properties of In situ particulate reinforced metal matrix composites Layer Produced by Laser Cladding

作　　者：张庆茂[1] 何金江[1] 刘文今[1] 钟敏霖[1] 

机构地区：[1]清华大学机械系激光加工研究中心

出　　处：《应用激光》2002年第2期109-112,共4页Applied Laser

基　　金：清华大学985重点项目

摘　　要：采用激光预置熔覆技术,通过在FeCSiBRe合金粉末中单独添加强碳化物形成元素Zr和复合添加Zr、Ti、WC元素和碳化物,在中碳钢基体上制备出原位析出的颗粒增强铁基复合材料表层。利用光学显微镜、扫描电子显微镜(SEM)、能谱仪(EDAX),对熔覆层显微组织特征以及硬质颗粒的分布规律进行了观察、分析;利用显微硬度计检测了熔覆层的显微硬度。熔覆层显微组织特征是树枝状的先共晶奥氏体分布在共晶基体上的亚共晶组织。熔覆层与基体成良好的冶金结合且未观察到裂纹和孔隙。熔覆层内析出的硬质颗粒分别是以ZrC和Zr、Ti、W为主的复合碳化物,由于凝固前沿对颗粒的特殊扑获作用,主要分布在枝晶内与枝晶间。Metal matrix composite layers reinforced by in situ particles were formed by laser cladding using prepasted 2.4%Zr/FeCSiBRE and (2.4 wt% Zr+1.2 wt%Ti+ 15wt% WC)/FeCSiBRE alloy powders on the medium carbon steel substrate respectively. Due to the right selection of the processing parameters during the laser cladding, the porosity and crack free in situ paniculate metal matrix composites layers have been produced. The morphology, microstructure, interface structure and the distribution of the in situ particles in the clad layers were observed with optical microscope, scanning electron microscope with EDAX. The microstructural characteristics of metal matrix composite are the typical austen-ite dendrite distributed on the eutectic substrate. In situ particles can not only be trapped by the advanced solid/ liquid interface and thus distribute within dendrite, but also be pushed away by the interface into interdendritic regions together with the eutectics. The martensite transformation is observed after the rapid cooling processes also. There is good metallurgical bonding between the layer and substrate. The EDAX chemical compositional analysis proved that the particles are Zr compound carbide and Zr、Ti、 W compound carbide respectively in different layers. The microhardness varied from Hv0. 2 800 to Hv0.2 1100 and Hv0. 2 800 to Hv0.2 1000 from the top to the bottom of the cross section respectively.

关 键 词：原位析出 亚共晶组织 马氏体 相变 激光熔覆 金属基复合材料 颗粒增强 

分 类 号：TB33[一般工业技术—材料科学与工程] TG174.44[金属学及工艺—金属表面处理]