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兵工学报 ›› 2025, Vol. 46 ›› Issue (10): 250499-.doi: 10.12382/bgxb.2025.0499

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Al15(CoCrFeNi)85高熵合金的动态冲击力学响应与变形机制

凌静, 梁延祥, 敬霖*()   

  1. 西南交通大学 轨道交通运载系统全国重点实验室, 四川 成都 610031
  • 收稿日期:2025-06-12 上线日期:2025-11-05
  • 通讯作者:
  • 基金资助:
    国家自然科学基金项目(12122211); 国家自然科学基金项目(52301111)

Dynamic Impact Mechanics Response and Deformation Mechanisms of Al15(CoCrFeNi)85 High-entropy Alloy

LING Jing, LIANG Yanxiang, JING Lin*()   

  1. State Key Laboratory of Rail Transit Vehicle system, Southwest Jiaotong University, Chengdu 610031, Sichuan, China
  • Received:2025-06-12 Online:2025-11-05

摘要:

以具有抗冲击应用潜力的亚稳态面心立方晶格(Face-Centered Cubic,FCC)/体心立方晶格(Body-Centered Cubic,BCC)双相Al15(CoCrFeNi)85高熵合金为研究对象,旨在系统研究其动态压缩力学行为并揭示微观变形机制。采用万能试验机、霍普金森压杆、电子背散射衍射、分子动力学模拟研究了其静动态压缩力学性能,分析了其塑性应力-应变响应特性、应变率敏感性及微观变形机制,阐明了其动态压缩强化机理,建立了其动态压缩本构模型。结果表明,动态压缩加载下该合金表现出明显应变率强化效应,且流动应力随应变先缓慢增长后显著上升;初始微观结构为FCC(71.4%)/BCC(28.6%)双相结构,单轴压缩加载下发生FCC相向BCC相转变,且受应变率影响较大,准静态压缩下FCC相与BCC相比值约为1∶1,动态下约为3∶7,该相变直接导致流动应力突变;MD模拟进一步证实了应变率效应显著,塑性变形机制以相变主导,且随BCC相增多由全位错滑移主导BCC相变形;基于Johnson-Cook模型,建立了亚稳态双相Al15(CoCrFeNi)85合金动态压缩本构模型。本研究为其在抗冲击结构材料设计与应用提供了重要理论依据。

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 metastable face-centered cubic (FCC) and body-centered cubic (BCC) dual-phase Al15(CoCrFeNi)85 high-entropy alloy has significant application prospects in the field of impact-resistant structural materials. The paper aims to systematically examine its dynamic response and compressive deformation mechanisms. The quasi-static and dynamic compressive mechanical properties of the high-entropy alloy are 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 of the high-entropy alloy are analyzed, and its strengthening mechanism under dynamic compression is elucidated. A dynamic constitutive model for the metastable dual-phase Al15(CoCrFeNi)85 is established. The high-entropy alloy exhibits strain rate sensitivity, of which the flow stress initially increase gradually and then rises sharply at larger strains. The base material is consisted of 71.4% FCC and 28.6% BCC phases. The FCC-to-BCC phase transformation under uniaxial compression is strain-rate-dependent. The ratio of FCC-to-BCC phase transformation under quasi-static loading is approximately 1∶1, whereas it is approximately 3∶7 under dynamic loading. MD simulations confirm the phase-transformation-dominated deformation mechanism. The plastic deformation shifts to full dislocation slip in BCC phases as their fraction increases. The dynamic stress-strain response is predicted using a modified Johnson-Cook constitutive model. These findings can provide theoretical guidance for the design and application of HEAs in impact-resistant structures.

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

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