This paper proposed an electromagnetic loading process with the high-speed impact. Al-4.2% Cu alloy bars were used to employ electromagnetic impact (EI) experiments. Deformation mechanism and microstructure evolution of EI samples were revealed by theoretical model and microstructure characterizations. The EI process had impact force (peak value 40 kN) and impact velocity (peak value 6.7 m/s) during a short time period (1.25 ms). Adiabatic shearing mechanism dominated the whole deformation process, causing that significant microstructure characteristic was adiabatic shear bands (ASBs). The theoretical analysis implied that the formation of ASBs was accounted for the radial velocity gradient. Most plastic deformations concentrated in ASBs, and approximately pure shear deformations resulted in adiabatic temperature rise of 0.33–0.42 T_m inside ASBs. The width of ASBs was about 135 μm, in which original equiaxial grains were elongated into laminated sub-structures. TEM observations showed multi-slip systems were simultaneously actuated due to severe shear deformations. High dislocation density and dislocation tangles distributed with the ASBs. Adiabatic temperature rise and distorted energies drove sub-grains rotate into recrystallization grains (70–280 nm) with large angle grain boundaries. The needed maximum time (45 μs) for rotational dynamic recrystallization was far less than that of plastic deformation, indicating that rotational dynamic recrystallization mechanism contributed to the formation of recrystallization grains.

本文提出了一种具有高速冲击力的电磁加载过程。使用Al-4.2％Cu合金棒进行电磁冲击（EI）实验。通过理论模型和微观结构表征，揭示了EI样品的变形机理和微观结构演变。EI过程在短时间内（1.25 ms）具有冲击力（峰值40 kN）和冲击速度（峰值6.7 m / s）。绝热剪切机制主导了整个变形过程，导致显着的微观结构特征是绝热剪切带（ASBs）。理论分析表明，ASB的形成是径向速度梯度的原因。大部分塑性变形集中在ASB中，大约纯剪切变形导致绝热温度升高0.33–0.42ASB内部的T _m。ASB的宽度约为135μm，其中原始的等轴晶粒被拉长成层压的子结构。TEM观察表明，由于严重的剪切变形，多滑移系统同时被致动。高位错密度和与ASB一起分布的位错缠结。绝热温度升高和能量变形驱使亚晶粒旋转成具有大角度晶界的重结晶晶粒（70-280 nm）。旋转动态再结晶所需的最大时间（45μs）远小于塑性变形所需的最大时间，这表明旋转动态再结晶机理有助于形成再结晶晶粒。