Effect of ultrasonic impact treatment on the microstructure and mechanical properties of diffusion-bonded TC11 alloy joints

Abstract

To derive the higher mechanical properties of diffusion-bonded joints at a low bonding temperature, ultrasonic impact treatment (UIT) was used to increase the dislocations and refine the microstructure of faying surfaces prior to diffusion bonding. The results show that a deformation layer with a thickness of 30μm formed near the impacted TC11 alloy surface, with many dislocation tangles, substructures, and dislocation cells in this layer. Diffusion bonding experiments were performed for both original samples and UIT samples. For the original TC11 alloy, the average shear strength of the diffusion-bonded joints increased with an increase in the bonding temperature, and the joint strength was 550MPa for joints bonded at 820 °C for 30min under a pressure of 10MPa. However, the average shear strength of the TC11 alloy joints with UIT reached 560MPa for the joint that was diffusion-bonded at 780°C, whereas it was only 370MPa for the joint without UIT. Therefore, UIT of the alloy surface resulted in a joint with a high strength at a relatively low bonding temperature, which may be beneficial to inhibit the grain growth caused by the high temperature bonding process.