TU2无氧铜与铪的真空钎焊

使用BAg72Cu钎料对TU2无氧铜与稀有金属铪(Hf)进行真空钎焊。借助金相显微镜、超景深显微镜、扫描电镜、能谱分析、室温剪切试验等手段,分析了钎焊工艺参数(钎焊温度和保温时间)对钎焊接头组织及性能的影响。结果表明:真空钎焊后获得的焊缝组织致密而连续,焊缝区均存在三个不同形貌的区域:铪侧的黑色区、中间花纹状Ag-Cu共晶区和铜侧的峰峦状或鹅卵石状铜基固溶体区。随着钎焊温度升高和保温时间的延长,焊缝中峰峦状或鹅卵石状组织越来越大,黑色区也越来越宽,而中间共晶区则减小。黑色带状区域中的Hf元素含量均大于4%,明显超过了相图中Hf在Ag、Cu中的饱和固溶度,说明该区域中不可能仅存在铜或银与铪的二元固溶体组织,有可能存在三元固溶体或含铪金属化合物。两种工艺参数均对接头的剪切破断应力影响不大。

Vacuum Brazing Process of TU2 Oxygen-free Copper and Hafnium

The vacuum brazing process of TU2 oxygen-flee copper and hafnium was studied by using BAg72Cu filler metal.Through SEM,EDS,metailographic microscope and shear test,the effects of different process parameters(brazing temperature and holding time)on microstructure and properties of the joints were analyzed.The results show that the main microstructure of brazing ioints is composed of three main areas with different patterns-the black area beside nf,the mid area of Ag-Cu eutectic structure and the area of coppcer based solid solution near Cu.With the increase of brazing temperature and holding time,both the black area and the area of copper based solid solution become wider,however the mid area Of Ag-Cu eutectic structure become narrower.In the black area,Hf content is about over 4%,which is significantly more than the solid solubility limit of Hf both in Cu-Hf phase diagram and Ag-Hf phase diagram.That shows that it is impossible for only the binary solid solution of Cu-Hf or Ag-Hf to exist in the area.Maybe there is ternary solid solution or metallic compound with Hf.The two process parameters slightly influence the shear breaking stress.