Diffusion bonding of intermetallic Ti-47Al-2Cr-0.2Si sheet material and mechanical properties of joints at room temperature and elevated temperatures

A series of diffusion bonding tests was conducted on fine-grained ingot metallurgical Ti-47Al-2Cr-0.2Si (at%) sheet material with applied stress in vacuum. Optical and scanning electron microscope (SEM) investigations revealed that defect-free joints could be achieved at a bonding temperature of 1000 degrees C in spite of variations of stress in the range 20-40 MPa and bonding time in the range 1-3 h. Apart from metallographical characterization, mechanical testing was performed to verify the bonding quality. Therefore, tensile specimens with wedge-shaped bonding zone geometry were cut from the joined sheet samples and tested at room temperature, 700 degrees C and 1000 degrees C with an initial strain rate of approximately 1 x 10(-4) s. The tensile test results indicated that the tensile properties of the joints are comparable to those of the base material. Finally, a dissimilar Ti-47Al-2Cr-0.2Si/Ti-6Al-4V diffusion bonding couple was produced, characterized and mechanically tested at room temperature and 700 degrees C. (C) 1997 Elsevier Science Limited.