激光熔覆(Zr+WC)/FeCSiBRE合金的组织和性能

Investigation on Microstructural Characteristics and Properties of (1.2%Zr+40%WC)/FeCSiBRE Layer Produced by Laser Cladding

采用预置激光熔覆技术 ,在 4 5号钢基体表面上熔覆 (1.2 %Zr+40 %WC) /FeC SiBRE合金粉末 ,制备出原位析出的颗粒增强金属基复合材料表层。利用光学显微镜、扫描电子显微镜、能谱仪 ,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 ;利用显微硬度计对熔覆层显微硬度的分布进行了测量。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 ;奥氏体在随后的冷却过程中转变为马氏体。熔覆层与基体成良好的冶金结合 ;能谱分析表明熔覆层内原位析出的硬质颗粒是以WC为主的复合碳化物 ,弥散分布在枝晶内 ,也可被固液界面推移至晶间与共晶共存。颗粒的尺寸小于 1μm ;熔覆层显微硬度在 5 0 0～ 6 0 0HV0 .

Metal matrix composite layers reinforced by in situ WC particles were formed by laser cladding using pre pasted (1.2%Zr+40%WC)/FeCSiBRE alloy powder on the medium carbon steel substrate.The morphologies,microstructures,interface structure and the distribution of the WC particles in the clad layers were observed with optical microscope,scanning electron microscope with EDAX.The microstructure characteristics of metal matrix composites are the typical γ austenite dendrite distributed on the eutectic substrate.In situ WC particles can not only be trapped by the advanced solid/ liquid interface and 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 microhardness varies between 500～600 HV 0.2 .