冷却速度对Sn-Bi-X合金微观组织的影响  

Effects of Cooling Rates on Microstructure of Sn-Bi-X Solders

作　　者：陈海燕[1] 林振龙[1] 揭晓华[1] 张海燕[1] 郭黎 

机构地区：[1]广东工业大学材料与能源学院,广东广州510006 [2]高新锡业有限公司,广东惠州516123

出　　处：《铸造技术》2014年第1期1-4,共4页Foundry Technology

基　　金：国家自然科学基金资助项目(20971027);广东省部产学研结合项目(2010B090400207)

摘　　要：在Sn-5.0X-1.5Cu-Ni焊料合金中添加10%(质量分数,下同)的Bi,以期降低焊料熔点的同时消除Bi的偏析和合金脆性,研究了浇铸空冷和真空吸铸水冷两种不同冷却速度下无铅焊料合金的微观组织。用X射线衍射分析的方法,按最小二乘法原理,精确测定β-Sn的点阵参数,对Sn-10Bi-5.0X-1.5Cu-Ni合金的固溶度进行了测定;采用光学显微镜、扫描电镜和透视电镜观察合金微观组织和结构;通过DSC分析焊料的熔化和凝固过程;并测试了焊料的润湿性和力学性能。结果表明:随着凝固速度增加,晶格常数进一步增大,Bi在Sn中的固溶度也得到了提高;缓慢冷却的浇铸态合金显微组织中存在着大量的粗大针状Sn-Bi共晶组织,吸铸态合金组织中Bi以细小颗粒状均匀分布在Sn基体,没有偏析相形成,吸铸快冷条件下制备的Sn-10Bi-5.0X-1.5Cu-Ni的熔点为208.96℃,具有优良的润湿性,合金和焊点具有良好的力学性能。10%Bi （mass concentration） was added into Sn-5.0X-1.5Cu-Ni solder alloy to produce lead-flee solder at low melting point and eliminate the brittleness of soldering joint. The microstructure of the solders was explored at the cooling rates of air cooling under casting process and rapid water cooling under vacuum suction casting process. The solubility of the solder was measured with X-ray diffraction method by analyzing the crystal constant accurately base on the mathematic fundamentals of least square method. The microstructure of the alloys was studied using OM, SEM and TEM.The phase transformation and melting property were detected by DSC test. Spreading rate and mechanical properties of the solder were studied. The results show that the solubility of the alloy increases with the increase of cooling rate, the acicular coarse Sn-Bi eutectic microstructures exist in the alloy structure under slow air cooling during casting process. Under rapid water cooling condition, the lead-free solder Sn-10Bi-5.0X-1.5Cu-Ni has a melting point as low as 208.96 ℃, good wetting performance, high mechanical performance and the finer primary β-Sn crystal microstructure without forming Bi-segregation phase.

关 键 词：无铅焊料 快速凝固 偏析 熔点 力学性能 

分 类 号：TG425.1[金属学及工艺—焊接]