冲击相变宏观物理模型的校验新方法

The direct impact and reverse impact experimental technologies are built in the Young Science Foundation program. The phase transition, spalling characteristics and the influence of phase transition on spall are perfectly presented. Further, the remaining trace of α→ε→α phase transition is detected in the recovered phase sample.. Based on the significant progress that made about microstructure characterization of recovered phase samples in the Young Science Foundation program, the remaining trace of α→ε→α phase and its phase evolution and transition mechanism from the microscopic level are presented, through the available combination of microstructure characterization of recovered samples and large-scale molecular dynamics simulation in this continuous program. Depending on the experimental observation, “phase fraction” of directly checking data applied for the macroscopic physical model of shock phase is statistically obtained via characterizing the recovered sample with TEM and EBSD technique under the various shock loading conditions. By incorporating the macroscopic measured results, e.g. velocity profile of free surface, a novel checking approach is built for macroscopic physical model of shock induced phase transition.

在研青年科学基金巧妙结合正向和逆向加载实验，系统给出了不同加载压力下含相变材料的冲击加卸载历程及对层裂行为的影响机制，并在回收样品微观表征中发现了α→ε→α 相变残留痕迹。. 基于青年科学基金项目在回收相变样品微观表征方面取得的重要进展，本连续项目拟通过受载回收出样品微观表征和大规模分子动力学模拟的有机结合，确认纯铁材料α→ε→α 相变标志，从微观研究层面揭示α→ε→α 相变历程和转变机制；在α→ε→α 相变标志确认基础上，结合TEM和 EBSD技术微观表征不同加载压力回收纯铁样品，统计给出用于冲击相变宏观物理模型的直接校验数据“相变份额”，结合自由面速度剖面等宏观测量数据，建立一种冲击相变混合相宏观物理模型的校验新方法。

针对冲击相变物理模型校验这一核心目标，本青年－面上连续项目突破了平面高压冲击加载下纯铁材料宏观速度测量和受载样品同步完整回收的实验技术，通过对回收纯铁样品的微观表征，揭示了｛332｝<113>形成机制，确认了α→ε→α 相变历程的多种残留痕迹和α→ε→α 的相变机制，丰富了原青年基金项目仅确认“互成60º角三组｛112｝<111>孪晶结构”为α→ε→α 相变的残留痕迹和标志的认识；建立了描述纯铁α→ε→α冲击相变的相场模型和计算方法，给出了不同加载状态下纯铁的相变分布特征，与自由面测速和回收样品微观表征结果高度吻合，基本实现了建立冲击相变宏观物理模型校验新方法的目标。另外，探索研究了平面和柱面不同加载状态下纯铁材料的相变行为，结果指出相对于一维平面加载状态，柱面和球面等多维加载状态更有利于纯铁样品发生α→ε相变，指导团队成员成功申请国家自然科学基金青年项目1项。