【摘要】 选用合适的激光工艺参数及涂层成分,在45#钢基体表面得到了激光熔覆原位析出的Ni-Fe-Ti-B复合材料涂层.涂层中的粘结金属基体为γ-(Ni,Fe)和Nihcp,原位弥散析出相为呈现出颗粒状、细条状等分布的稳定相TiB2、Ni4B3及亚稳定相Ni2B、(Fe,Ni)3B型化合物.前两者已经细化成为纳米晶,而后两者晶粒度相对较粗.γ-(Ni,Fe)是稳定的Ni、Fe固溶体,而Nihcp形成于基体金属内部的堆垛层错作用;原位析出相产生于激光熔覆过程中涂层表面发生的原位燃烧反应或合金系快速凝固过程中的低熔点共晶作用.在基体与析出相的界面上存在高密度位错堆积,从而引起基体金属亚结构细化.更多还原

【Abstract】 In-situ separating out Ni-Fe-Ti-B composite coating has been fabricated on 45^# steel surface by laser cladding with optimal laser parameters and coating compositions. The bonding metal matrix is γ-（Ni, Fe） and Ni_hcp, and the in-situ separating out phases are stable TiB₂, Ni₄B₃ and metastable Ni₂B, （Fe, Ni）₃B type compounds with the shape of granular and thin strip. The former two are fine enough to present nano-crystalline while the latter two are relatively coarse. γ-（Ni, Fe） is stable solid solution of Ni and Fe, whereas the formation of Ni_hcp contributes to the stacking fault in the matrix. The in-situ separating out phases are produced from the combustion reaction in the coating surface or the low melting point eutectic reaction in the alloy system during laser cladding and the rapid solidification. High density dislocation pile-up lies in the interface of the matrix and the second phase, which induces the sub-structure fining of the matrix.更多还原