arXiv:2511.12995cond-mat.mtrl-scics.LG2025-11被引 2

用机器学习势重模拟铅在冲击下的动态响应,发现不同方向下相变与塑性行为差异。

Revealing the dynamic responses of Pb under shock loading based on DFT-accuracy machine learning potential

  • 基于高精度机器学习势,模拟铅在不同冲击方向下的原子级演化。
  • [001]方向出现快速可逆相变和堆垛层错,无孪生;[011]方向为缓慢不可逆塑性变形。
  • 结果揭示冲击取向对铅力学行为的关键影响,适合材料动力学研究者参考。

铅(Pb)是一种典型的低熔点延展性金属,是研究动态响应的重要模型材料。在冲击波加载下,其动态力学行为包含塑性变形和冲击诱导相变两个关键现象,但其内在机制仍不清晰。实验手段难以揭示这些过程。非平衡分子动力学(NEMD)模拟可捕捉原子尺度机制,如缺陷演化和变形路径,但以往研究受限于经验势的精度,可靠性存疑。本文基于新开发的铅锡合金机器学习势,重新研究了不同冲击取向下铅的微观结构演化。结果表明:沿[001]方向冲击时,铅呈现快速、可逆且大规模的相变及堆垛层错演化;塑性变形中未出现孪生现象,与以往研究不同。沿[011]方向冲击则导致缓慢、不可逆的塑性变形,并在Pitsch取向关系下产生局域的面心立方(FCC)到体心立方(BCC)相变。本研究为理解铅在极端条件下的微结构-性能关联提供了重要理论依据。

原文摘要 · Abstract (English)

Lead (Pb) is a typical low-melting-point ductile metal and serves as an important model material in the study of dynamic responses. Under shock-wave loading, its dynamic mechanical behavior comprises two key phenomena: plastic deformation and shock induced phase transitions. The underlying mechanisms of these processes are still poorly understood. Revealing these mechanisms remains challenging for experimental approaches. Non-equilibrium molecular dynamics (NEMD) simulations are an alternative theoretical tool for studying dynamic responses, as they capture atomic-scale mechanisms such as defect evolution and deformation pathways. However, due to the limited accuracy of empirical interatomic potentials, the reliability of previous NEMD studies is questioned. Using our newly developed machine learning potential for Pb-Sn alloys, we revisited the microstructure evolution in response to shock loading under various shock orientations. The results reveal that shock loading along the [001] orientation of Pb exhibits a fast, reversible, and massive phase transition and stacking fault evolution. The behavior of Pb differs from previous studies by the absence of twinning during plastic deformation. Loading along the [011] orientation leads to slow, irreversible plastic deformation, and a localized FCC-BCC phase transition in the Pitsch orientation relationship. This study provides crucial theoretical insights into the dynamic mechanical response of Pb, offering a theoretical input for understanding the microstructure-performance relationship under extreme conditions.

机器学习势冲击响应相变分子动力学

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