本团队张茂副教授、博士生施君儒等在Journal of Materials Research and Technology发表研究论文。

摘要：Ultrasonic vibration (UV)-assisted forming has been widely applied to enhance the plastic deformation of metals, yet its effects on the forming quality and strengthening behavior of the microstructure of the rolled surface remain insufficiently understood. In this study, UV-assisted rolling was employed to fabricate U-shaped and rectangular microchannels with a width of 0.5 mm on 1060 aluminum strips, using a self-developed device with UV amplitudes ranging from 0 to 10 μm. The forming quality, near-surface microstructure, and microhardness of the rolled microchannels were systematically characterized, and the underlying dislocation mechanisms were probed by molecular dynamics simulations. The results show that UV improves the geometric filling and depth-to-width ratio of the microchannels by approximately 26.7% and 44.2%, respectively, while reducing surface roughness. UV enhances the gradient microstructure and the microhardness at the bottom of the microchannel. Notably, despite the high stacking-fault energy of aluminum, UV promotes extensive stacking faults and Lomer-Cottrell locks in the near-surface region. MD simulations reveal that UV reduces the resolved shear stress and slows the slip of the Shockley partials, so that fewer partials are absorbed or annihilated at boundaries and more stacking faults are retained. By quantitatively decoupling the Hall-Petch and Taylor strengthening contributions, dislocation strengthening is shown to contribute approximately twice as much as grain refinement to the UV-induced microhardness increment, identifying dislocation multiplication as the dominant strengthening pathway in UV-assisted rolling.