激光熔覆MoSi2粉末涂层的组织结构和性能

用XRD、SEM、EDAX和显微硬度仪研究了 4 5钢基体激光熔覆MoSi2 粉末涂层的组织结构和硬度。结果表明 ,由于基体的稀释作用 ,涂层的相组成为FeMoSi、Fe2 Si和少量的Mo5Si3 。涂层组织呈现典型的细小枝晶组织特征 ,枝晶为FeMoSi领先相 ,枝晶间为FeMoSi和Fe2 Si两相共晶 ,组织中无孔隙和裂纹等缺陷。Mo、Si、Fe线扫描成分分析表明 ,这些元素都分布在涂层 基体界面处 ,且缓慢过渡 ,基体与涂层发生互扩散 ,为冶金结合。涂层硬度可达 84 5HV0 5 ,基体硬度为 180HV0 5 ,涂层硬度比基体高 3 7倍。从涂层到基体硬度逐渐降低 ,过渡区比较缓和。

Microstructure and Properties of the MoSi2 Powder Coating Clad by Laser Beam

Microstructure and hardness of the coating manufactured by laser cladding MoSi 2 powder on the 45 steel substrate were investigated through XRD,SEM and EDAX analyses and microhardness test respectively.The experimental results show that the phase constitution of the coating is composed of FeMoSi,Fe 2Si and a small amount of Mo 5Si 3 due to dilution of the substrate in the deposit.The microstructure of the coatings is characterized of typical fine dendrites.Dendrites are composed of FeMoSi primary phase and interdendritic areas are two eutectic phases of FeMoSi and Fe 2Si.There are no defects of pores,cracks etc.in microstructures.All composition distributions of line scanning of Mo,Si,Fe in the interfaces between coating and substrate change gradually,the elements of coating and substrate diffuse each other,the coating and the substrate are bonded metallurgically.The hardness of the coating reaches 845HV0 5,which is 3 7 times higher than that of the steel substrate(180HV0 5).Hardness decreases gradually from the coating to the substrate,the distribution of hardness is comparatively mild.