Effect of interlayer on microstructure and mechanical properties of Al–Ti ultrasonic welds

Abstract

Joints of Al6061 and Ti6Al4 V alloys with pure Al-particle interlayers were conducted using ultrasonic spot welding. The microstructure, hardness, lap shear strength and fracture energy were measured for different welding energies. With increasing welding energy delivered through the sonotrode, the lap shear strength of the joints increased, reaching about 106 MPa at a welding energy of 1100 J, at which failure occurred in the pull-out mode. In the weld region, the hardness of Al6061 alloy increased with increasing weld energy, whereas the hardness of Ti6Al4 V did not change discernibly. No brittle intermetallic compounds were observed in the joints. Moreover, two simple mechanisms were described for the formation of ultrasonic spot-welded Al–Ti joints with and without the pure Al interlayer.