Ultrasound-aided laser additive manufacturing achieves synergistic optimization of microstructure and properties in high-temperature titanium alloy

High-temperature titanium alloys serve as candidate materials for critical aerospace components such as integrated blisks, expected to replace certain superalloys and achieve vehicle lightweighting. Laser Directed Energy Deposition (LDED) is a prevalent additive manufacturing technique for fabrication of large-scale complex components. However, LDED faces challenges including uncontrollable microstructures and prominent residual stresses due to its unique metallurgical characteristics: ultra-fast cooling, high thermal gradient solidification, and cyclic reheating. Previous studies confirm that external ultrasonic fields can regulate microstructures without altering the alloy compositions. Therefore, this work applies an external ultrasonic field to intervene in the LDED molten pool of high-temperature titanium alloy Ti60, focusing on the effects on microstructure, residual stress, and high-temperature mechanical properties. The results indicate that the ultrasound eliminates the banded microstructure in traditional LDED titanium alloys, and it increases the compressive residual stress of multilayer samples. Consequently, the samples exhibit a marginally reduced high-temperature yield strength and ultimate tensile strength but significantly enhanced plasticity. This study provides a deep insight for the ultrasound-aided LDED of high-temperature titanium alloy.