Ti-28Ni钎料真空钎焊TZM合金接头界面组织与力学性能

Interfacial Microstructure and Properties of TZM Alloy Joints Brazed Using Ti-28Ni Filler Metal

摘要:

在钎焊温度为1040 ℃时,采用Ti-28Ni(质量分数,%)钎料实现了TZM合金的真空钎焊连接。采用SEM、EDS等方法分析了接头界面的微观组织结构,并研究了保温时间对TZM合金接头界面结构和性能的影响规律。结果表明,接头的典型界面组织结构为：TZM/Ti_ss/δ-Ti₂Ni/Ti_ss/TZM；随保温时间的延长,焊缝宽度逐渐变小,其中连续的Ti_ss层厚度基本无变化,中间的δ-Ti₂Ni层厚度有所降低；同时,TZM母材向焊缝中的溶解量增加。保温时间较短时,焊缝中残留有未溶解的TZM块,延长保温时间使母材溶解更充分。当保温时间为10 min时,接头平均抗剪强度最高为92.6 MPa,断裂发生于δ-Ti₂Ni层,为脆性沿晶断裂。

关键词:TZM合金;真空钎焊;界面组织;力学性能

Abstract:

TZM alloy was successfully brazed using Ti-28Ni as filler metal at 1040℃. The effect of holding time on interfacial microstructure and mechanical properties of brazed joints was studied and the typical microstructure of joint was detected using SEM, EDS. As a result, the typical interfacial microstructure was: TZM/Ti_ss/δ-Ti₂Ni/Ti_ss/TZM. As increased the holding time, the width of the braze seam decreased, the continuous width of Ti_ss basically did not change, and the width of central δ-Ti₂Ni layer decreased to some extent. Meanwhile, the diffusion of TZM into base materials enhanced. When the holding time was relatively short, there was undissolved TZM block in the weld joints, and the base metal could dissolve thoroughly while extending the holding time. The highest average shear strength of 92.6 MPa was achieved when the holding time was 10 min, and the fracture happened at δ-Ti₂Ni layer, which was intergranular brittle fracture.

Key words:TZM alloy; Vacuum brazing; Interfacial microstructure; Mechanical property