Influence of Effective Physical Contact Area on Microstructure and Mechanical Properties of Diffusion-Bonded TC4/1060Al Joints

In the present study, dissimilar TC4 alloy and 1060Al alloy were successfully diffusion-bonded at a very low temperature about 410 degrees C by improving the effective physical contact area. A sound joint with a crack-free interface and a high shear strength (128MPa) is obtained with a combination of TC4 surface roughness of 109.90m (S-a) and 1060Al surface roughness of 101.43m (S-a), and customized parallel surface scratches. Under this condition, the two parent metals share the largest contact area during the physical contact stage of diffusion bonding process, which is consistent with the theoretical calculation. The results show that no Ti-Al binary intermetallic compounds are observed at the interface of the joints. The maximum shear strength of the joint reaches 128MPa with optimized bonding parameters (410 degrees C for 120min with a pressure of 20MPa), which is higher than the shear strength of 1060Al (80MPa) base metal. The fractography analysis indicates the joints failed with a ductile fracture at the 1060Al side.