激光熔覆Ni-Ti-Si合金的组织及微观力学性能  

Microstructure and Micromechanical Properties of Ni-Ti-Si Coating Deposited by Laser Cladding

作　　者：李明川 张培磊[1,2] 于治水 闫华[1,2] 叶欣 李绍伟[1,2] Li Mingchuan;Zhang Peilei;Yu Zhishui;Yan Hua;Ye Xin;Li Shaowei(Shanghai University of Engineering Science,Shanghai 201620,China;Shanghai Collaborative Innovation Center of Laser Advanced Manufacturing Technology,Shanghai 201620,China)

机构地区：[1]上海工程技术大学,上海201620 [2]上海市激光先进制造技术协同创新中心,上海201620

出　　处：《稀有金属材料与工程》2019年第4期1225-1230,共6页Rare Metal Materials and Engineering

基　　金：国家自然科学基金(51375294;51605276;51405288);上海汽车工业科技发展基金会(1604);上海市"创新行动计划"基础研究领域项目(17JC1400600;17JC1400601)

摘　　要：采用激光熔覆技术在铜表面制备了55Ni-35Ti-10Si (at%)合金熔覆层,熔覆层呈现上、下两层。利用光学显微镜(OM)、扫描电子显微镜(SEM)、X射线衍射仪(XRD)、能谱仪(EDS)分析合金熔覆层的组织。结果表明,熔覆层上层组织为树枝晶,组成相为初生钛固溶体+枝晶间Ni_3Si;下层组织为胞状晶,组成相为初生钛固溶体+枝晶间铜固溶体,胞状晶区高度约为200μm。利用KGT和LKT改进模型计算得出熔覆层熔池凝固过程枝晶尖端过冷度-凝固速度曲线,从热力学角度分析熔覆层出现分层的机理。对熔覆层进行显微硬度试验,得到上层树枝晶区域和下层胞状晶区域平均硬度(HV)分别为8000和2200 MPa。下层胞状晶区域的存在有利于熔覆层与基体间性能过渡,提高了熔覆层稳定性。A cladding layer 55Ni-35Ti-10Si(at%) was synthesized on copper using laser cladding, which was composed of two kinds of microstructures. The microstructures of the cladding layer were characterized by optical microscope(OM), scanning electron microscope(SEM), X-ray diffraction(XRD) and energy dispersive spectrometer(EDS). The results show that the phases in upper layer are Ti solid solution+Ni3Si and the morphology is dendritic. The under layer is composed of Ti solid solution+Cu solid solution and the morphology is cellulate. The crystal growth in solidification process was analysed using a modification model which is combined Kurz-Giovanola-Trivedi(KGT) model with Lipton-Kurz-Trivedi(LKT) model. The mechanism of cladding layer stratification was studied by thermodynamics. The microhardness of cladding layer was tested. The average hardness(HV) of upper layer and under layer are 8000 and 2200 MPa,respectively. The synthesis of under layer is beneficial to the performance transition between the cladding layer and substrate, increasing the stability of cladding layer.

关 键 词：激光熔覆 镍基合金 铜表面改性 快速凝固 

分 类 号：TG174.44[金属学及工艺—金属表面处理]