(1. 四川大学 材料科学与工程学院，成都 610065；2. 西华大学 材料科学与工程学院，成都 610039)
摘 要: 测试了Sn-3.5Ag-2Bi无铅焊料的压入蠕变应力指数n、蠕变激活能Q及其结构常数A，推导了压入蠕变稳态蠕变速率的本构方程，总结了压入蠕变随温度和应力的变化规律以及蠕变塑性变形机制，并初步探讨提高Sn-3.5Ag-2Bi无铅焊料抗蠕变性能的有效途径。结果表明：Sn-3.5Ag-2Bi无铅焊料的应力指数(n)为3.304、蠕变激活能(Q)为61.181 kJ/mol，材料的结构常数(A)为0.679；并得出压入蠕变稳态蠕变速率的本构方程；压入蠕变的位移量随温度的升高和应力的增加有规律地变大；通过分析其蠕变前后的微观结构和组织的变化，认为Sn-3.5Ag-2Bi无铅焊料蠕变塑性变形机制主要由位错滑移和位错攀移共同控制。
关键字: Sn-3.5Ag-2Bi无铅焊料；压入蠕变；应力指数；激活能；微观组织
（1. College of Materials Science and Engineering, Sichuan University, Chengdu 610065, China;2. College of Materials Science and Engineering, Xihua University, Chengdu 610039, China）
Abstract:The indentation creep stress exponent (n), creep activation energy (Q) and material structure constant (A) of Sn-3.5Ag-2Bi lead-free solder were measured, and the constitutive equation of the indentation creep steady-state creep rate was derived. The law that indentation creep changes with the stress and the temperature changing and creep plastic deformation mechanisms were summarized. The effective ways of raising Sn-3.5Ag-2Bi lead-free solder anti- creep property was also discussed. The results show that the stress exponent (n) is 3.304, creep activation energy (Q) is 61.181 kJ/mol and the material structure constant (A) is 0.679. The constitutive equation of the indentation creep steady-state creep rate is also derived. The displacement of indentation creep is enlarged regularly with the rising temperature and increasing stress. Through the analysis of changes of the micro-structure and organization before creep and after creep, the plastic deformation mechanisms of Sn-3.5Ag-2Bi lead-free solder creep are dominated by both dislocation slipping and dislocation climbing mainly.
Key words: Sn-3.5Ag-2Bi lead-free solder; indentation creep; stress exponent; activation energy; microstructure
