Ti活度对Al2O3/AgCuTi/Fe-Ni-Co钎焊接头机械性能和微观组织结构的影响

Effects of Ti Activity on Mechanical Performance and Microstructure of Al2O3/AgCuTi/Fe-Ni-Co Brazed Joints

摘要:

采用AgCuTi钎料实现了Al₂O₃陶瓷与Fe-Co-Ni合金的钎焊连接,并调查了不同钛含量的钎料对Al₂O₃/AgCuTi/Fe-Ni-Co钎焊接头机械性能和微观组织结构的影响。扫描电子显微镜(SEM), X射线能量色散光谱仪(EDS), X射线衍射仪(XRD)及电子万能试验机用于分析钎焊接头的机械性能和微观组织结构,结果表明:钛含量的增加明显提高AgCuTi钎料与Al₂O₃陶瓷的相互作用,在Al₂O₃/Ag-Cu-Ti界面生成一层由Ti-Al 和 Ti-O化合物组成的反应层。Al₂O₃/AgCuTi/Fe-Ni-Co钎焊接头的抗拉强度随钛含量的增加而增加,当钛含量提高到8wt.%时,抗拉强度达到最大值78Mpa。通过微观组织结构分析发现,采用AgCu4Ti在890℃保温5min的条件下可以获得较好的钎焊接头,典型接头的微观组织结构为Al₂O₃/TiAl+Ti₃O₅/NiTi+Cu₃Ti+Ag(s,s)/Ag(s,s)+Cu(s,s)+(Cu,Ni)/Fe-Ni-Co。采用AgCu8Ti获得的钎焊接头的界面反应层与AgCu4Ti差异不大,但反应层稍微增厚,并伴有TiO和Ti3Al在Al₂O₃/Ag-Cu-Ti界面生成。

Abstract:

Al₂O₃ ceramic/Fe-Ni-Co joints are achieved using Ag-Cu-Ti filler alloy in the study to investigate the dependence of the joint microstructure and mechanical performance on the Ti content. Scanning electron microscope (SEM), energy dispersive X-Ray spectrometer (EDS), X-Ray diffractometer (XRD) and electronic universal testing machine are used to characterize the microstructure and mechanical performance of the joints. The results show that the increase of Ti content can obviously intensify the interaction between Al₂O₃ and Ag-Cu-Ti. A layer of Ti-Al and Ti-O products is observed at the interface of Al₂O₃/AgCuTi. The tensile strength of Al₂O₃/AgCuTi/Fe-Ni-Co joint increase as the Ti content increased from 2 wt% to 8 wt.%, and the tensile strength of brazing joint reached the maximum value of 78MPa. Good reaction layer formed by metallurgical reaction at the interface of Al₂O₃/AgCu4Ti, and the typical microstructure is Al₂O₃/TiAl+Ti₃O₅/NiTi+Cu₃Ti+Ag(s,s)/Ag(s,s)+Cu(s,s)+(Cu,Ni)/Fe-Ni-Co brazed at 890_oC for 5 min. Compared with AgCu4Ti filler, the microstructure of the joints change slightly when addition of the active element Ti to 8 wt.% except for the increase of the thickness of reaction layer adjacent to Al₂O₃ ceramic and accompanied the formation of TiO and Ti₃Al in the Al₂O₃/Ag-Cu-Ti interface.