Infrared joining of titanium aluminides by using Ti-15Ni-15Cu foil
The infrared joining of titanium-aluminides Ti{sub 50}Al{sub 50}, Ti{sub 60}Al{sub 40} and Ti{sub 70}Al{sub 30} at T{sub w} = 1,100{approximately}1,200 C for 30{approximately}60sec using Ti-15Cu-15Ni foil as brazing filler-metal was investigated. Multilayered structures are formed by isothermal solidification following solid-state interdiffusion. The diffusion of Al atoms is the main controlling factor pertaining to the microstructural evolution of the joint interface. Seven characteristic zones at T{sub w} can be distinguished in the Ti{sub 50}Al{sub 50} joint: {gamma}-TiAl (I and II), {alpha} + {beta} two-phase mixed, high Al% {alpha}-phase, {alpha}{sub 2}-Ti{sub 3}Al, {beta}-Ti and residual liquid filler-metal. Five characteristic zones at T{sub w} are obtained in the Ti{sub 70}Al{sub 30} joint: {alpha}{sub 2}-Ti{sub 3}Al, {alpha}{sub 2} + {beta} two-phase mixed, {alpha} + {beta} two-phase mixed, {beta}-Ti and residual liquid filler-metal. The observed joint microstructures at room temperature are obtained from the phase transformation of these well-established high-temperature phases during cooling. A step-by-step microstructural evolution mechanism at T{sub w} = 1150 C is proposed individually for Ti{sub 50}Al{sub 50} and Ti{sub 70}Al{sub 30} alloys. These steps are in good agreement with the observed microstructures and are consistent with the multiphase diffusion theories in solid-state systems. The microstructural evolution of Ti{sub 60}Al{sub 40} joint interfaces can also be explained by the proposed step mechanisms for Ti{sub 50}Al{sub 50} and Ti{sub 70}Al{sub 30} alloys.
- Research Organization:
- Chung-Shan Inst. of Science and Technology, Lung-Tan, Tao-Yuan (TW)
- Sponsoring Organization:
- National Science Council of Republic of China
- OSTI ID:
- 20001587
- Report Number(s):
- CONF-981104--; ISBN 1-55899-458-0; ISSN 1067-9995
- Country of Publication:
- United States
- Language:
- English
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