冲击载荷作用下铁基合金相变的相场方法研究

As a powerful approach to studying microstructure evolution, e.g. phase transformation in materials, the phase field method (PFM) has found successful applications in physics and material science. However, for the lack of considering dynamic loading and the combination of plastic deformation and phase transformation, the PFM gains a little application in mechanics, especially in impact dynamics. In this project, a phase field model with combination of plastic deformation and phase transformation will be developed to predict mesoscale morphological and microstructure evolution in ferrous alloys subjected to impact, which is significant to improving the safety of structure materials employed in defense. Based on theoretical analysis and numerical simulation, the whole stress field evolution during phase transformation in ferrous alloy is investigated using developed PFM. And moreover, the influences of some factors, such as stress, strain, strain rate and temperature, on plastic deformation, martensite nucleation and growth are studied to investigate the mechanism of impact induced phase transformation in ferrous alloys. The substantive coupling of martensite morphology evolution with plastic zone extension is carried out in the developed PFM. Finally, the PFM algorithm developed in this project is of high efficiency and accuracy. And it will make contributions to the development of simulation tools for microstructure evolution in materials.

相场方法是研究材料相变等微结构演化过程的有效途径之一，在物理和材料科学领域取得了成功应用。然而，由于没有考虑动态载荷及塑性与相变的耦合作用，目前的相场方法在力学学科特别是冲击动力学中应用较少。本项目通过建立考虑塑性变形和材料相变耦合效应的相场方法来研究铁基合金在冲击载荷作用下的材料微结构形态演化过程，对提高国防领域结构材料的安全性有重要意义。以理论模型分析和数值计算为主要手段，用所发展的相场方法分析合金材料相变过程中的全场应力分布，并研究应力、应变、应变率和温度等因素对塑性变形及马氏体相形核、生长演化等的影响，并对合金材料冲击相变机理进行研究。实现铁基合金冲击相变中马氏体相形态演化与塑性区扩展的真正意义上的耦合作用，为新材料合成和改性等提供科学依据。同时，本项目中相场方法高效高精度算法研究有助于发展材料微结构演化的模拟计算和仿真工具。