【摘要】 采用钛铁、硼铁为预置粉末,利用激光熔覆搭接技术在碳钢基体上制备了Fe-Ti-B系原位自生颗粒增强Fe基复合涂层。利用X射线衍射仪、光学显微镜、扫描电镜、电子探针对熔覆层的相组成和显微组织进行了研究,并用洛氏硬度计测量了涂层硬度。结果表明,涂层中原位自生的增强粒子包括TiB2、FeB、Fe2B和Fe2Ti。且随着涂层中Ti,B原子比例的不同,涂层的相结构发生相应演变。当涂层增强相为FeB+Fe2B+TiB2和TiB2+Fe2Ti时,涂层的塑性降低,在激光熔覆应力的作用下产生裂纹,当涂层增强相为Fe2B+TiB2及TiB2,可获得致密、无缺陷的熔覆层。同被强化基体相比,熔覆层硬度有较大提高,且增强相为FeB+Fe2B+TiB2的涂层具有最高的硬度。更多还原

【Abstract】 In situ Fe-Ti-B particulate reinforced Fe-based composite coatings were fabricated on mild carbon steel substrate by laser cladding using ferrotitanium and ferroboron powder mixtures as the precursor.The phase constituents and microstructure of the composite coatings were investigated by means of XRD,OM,SEM and EPMA.The hardness of the composite coatings was examined by Rockwell hardness test.The results show that in situ formed reinforcements in the composite coatings were TiB₂,FeB,Fe₂B and Fe₂Ti.The phase constituents of the coatings varys with the changing of mole ratio of Ti and B in the precursor.When the reinforcements presented in the composite coatings were FeB+Fe₂B+TiB₂ or TiB₂+Fe₂Ti,plasticity of the composite coatings deteriorated and cracking occurred due to the residual stress formed in the laser cladding process.However,with Fe₂B+TiB₂ or TiB₂ as reinforcements,dense and defect-free coatings were obtained.Compared with the substrate,hardness of the clad layers improved markedly.Furthermore,the coating with FeB+Fe₂B+TiB₂ as reinforcements showed the highest hardness.更多还原