Effect Of Re On The Properties Of High Strength Ti-based Filler Metal

Ti-based filler metal has a moderate temperature, good corrosion resistance, high strength at room and high temperature,so it have been widely sused in the aerospace field. With the rapid development of space technology, brazed joint service environment become increasingly harsh, high strength and reliability of solder increasing attrak people’s attention. REE as minor alloying elements, known as "vitamin," in the metal filed. RE has also been recorded in solders applications, but few rare added into Ti-based filler metal which was used in aerospace. some technology development makes this study become very necessary.In this paper, Ti-15Cu-15 Ni, Ti-15Cu-25 Ni, Ti-21Cu-9Ni-13 Zr was researched. rare earth was added into this three filler metal to study the effect of RE on microstructure, physical properties, wetting properties and mechanical properties and then to optimize filler metal alloys’ composition to obtain the best overall performance, The results show that: Rare earths La and Nd was added into Ti-15Cu-15 Ni, Ti-15Cu-25 Ni, Ti-21Cu-9Ni-13 Zr, and then produced fine-grain strengthening, solid solution strengthening and second phase strengthening. These effect the increasingly rising trend on hardness of these three filler metals, the maximum hardness is respectively 29%、3%、4% higher than base fil 了 er metal. Studies have shown that rare earth elements after added into these three types of filler metals have improve the usability at various degrees. When rare earth content is 0.5%, the spreading area of Ti-15Cu-15Ni-xRE was 38.2mm2 that was more 5.7% than base filler meatl; When rare earth content is 0.1%, the spreading area of Ti-15Cu-25Ni-xRE was 34.9mm2 which was improved 28.5% than base metal; and When rare earth content is 0.3% the spreading area of Ti-13Zr-21Cu-9Ni-xRE was 88.8% higher than base filler metal. The impact of rare earth elements La, Nd on the shear strength and wettability have the same trend, the joint shear strength of Ti-15Cu-15Ni-0.5% RE brazing filler metal was more 69.6% than the base joint which was 244.6MPa. The shear strength of Ti-15Cu-25Ni-0.1% RE brazing filler metal joints reached the maximum 174.1MPa which increased 15.5% compared the base filler metal. The shear strength of Ti-13Zr-21Cu-9Ni-0.3% RE joint achieved the maximum 157.1MPa, that was more 45.2% than the joint of base filler metal. In addition, rare earth elements not only improved the shear strength of joint, but also decreased the brittle of joint.