关键词: 高熵合金, 动态力学性能, J-C本构模型, 分子动力学模拟

Abstract: The FCC/BCC dual-phase Alx(CoCrFeNi)100-x high-entropy alloys (HEAs) exhibit outstanding comprehensive properties, demonstrating significant potential for impact-resistant structures. This study focused on a metastable dual-phase Al15(CoCrFeNi)85 fabricated via rolling and aging processes. The quasi-static and dynamic compressive mechanical properties were characterized using a universal testing machine, split Hopkinson pressure bar (SHPB), electron backscatter diffraction (EBSD), and molecular dynamics (MD) simulations. The plastic stress-strain response, strain rate sensitivity, and microscopic deformation mechanisms were analyzed. The strengthening mechanism under dynamic compression was elucidated. The dynamic constitutive model was established. The alloy exhibited strain rate sensitivity, with the dynamic compressive flow stress showing an initial steady increase followed by a sharp rise with increasing strain. The base material consisted of 71.4% FCC and 28.6% BCC phases. Under uniaxial compression, the processing of the FCC to BCC phase transformation was strain-rate-dependent. Here was a balanced fraction (1:1) of FCC/BCC phases under quasi-static loading, whereas it was approximately 3/7 under dynamic loading. MD simulations confirmed the phase-transformation-dominated deformation mechanism. The plastic deformation shifted to full dislocation slip in BCC phases as their fraction increases. A modified Johnson-Cook constitutive model predicted the dynamic stress-strain response. These findings can provide a theoretical guidance for the design and application of HEAs in impact-resistant structures.

Key words: high entropy alloy, dynamic mechanical properties, J-C constitutive model, molecular dynamics simulation