High-strain-rate deformation in ultrasonic additive manufacturing

High-strain-rate deformation in ultrasonic additive manufacturing was analyzed by performing microstructural characterization via electron microscopy. The micro-asperities on the top tape surface, which were formed by contact with the sonotrode surface, underwent cyclic deformation in the shear direction at high strain rates during welding with an additional tape. This caused plastic flow and crushing of the micro-asperities, and a flattened interface was formed between the upper and lower tapes. Further, surface oxide films were fractured and dispersed by ultrasonic vibration, and metallurgical welding was achieved. (C) 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.