(1. 北京航空航天大学 材料科学与工程学院，北京 100191；
2. 中国航发北京航科发动机控制系统科技有限公司，北京 100191)
摘 要: 金属表面熔覆处理是改善其耐磨性的有效手段，但熔覆过程温度变化较快，不易于直接测量。基于ANSYS模拟计算获得熔覆层温度变化，并进行组织分析，构建工艺-温度-与组织性能之间的关系规律。利用氩弧作为热源在铜基体上微区熔凝制备锡青铜熔覆层。通过金相显微镜、电子探针等对熔覆过程温度场不同位置处的微观组织观察分析，确定微观组织和热流密度之间的定性关系。通过对微小熔池内部温度分布的数值模拟和微观组织的观察分析，建立熔池内部晶体形态、大小、分布和过冷度与冷却速率的关系模型，重点对锡青铜熔覆层中柱状晶向等轴晶的转变进行研究。结果表明：晶粒尺寸、枝晶臂间距、析出相δ相和单质Pb大小与热流密度负相关，确定了柱状晶/等轴晶转变(CET转变)与热流密度的数学模型。通过对模拟参数的调整可将该模型扩展应用至不同材料微区熔覆制备工艺。
关键字: 微区熔覆；凝固组织；有限元模拟；热流密度；CET转变
（1. School of Material Science and Engineering, Beijing University of Aeronautics and Astronautics, Beijing100191, China;
2. China Aero Beijing Aero Engine Control System Technology Co., Ltd., Beijing 100191, China）
Abstract:The metal surface cladding is an effective means to improve the wear resistance of the metal, but the temperature of cladding process changes rapidly and is not easy to be measured directly. The temperature change of cladding layer was obtained based on ANSYS simulation calculation, and the relationships between process, temperature and microstructure were established. The tin bronze cladding layer was prepared on the copper substrate, using argon arc as the heat source. The qualitative relationship between the microstructure and heat flux was determined by analyzing microstructure at different positions of the temperature field during cladding process. Through the numerical simulation of the temperature distribution in a small molten pool and analyses of microstructures, the relationship model of the crystal form and size, super-cooling degree and cooling rate was proposed to determine. The results show that the grain size, the dendrite arm spacing and the size of precipitate phase are negatively correlated with the heat flux, and the model of columnar crystal/equiaxial crystal transition (CET transition) and heat flux was established. By adjusting the simulation parameters, the model can be extended to different materials micro-zone cladding processes.
Key words: microzone cladding; solidification microstructure; finite element simulation; heat flux; CET transition
