δ钚中氦泡行为的分子动力学模拟研究

There is significant application value in weapon systems and nuclear power systems for δ-phase Pu. The mechanical properties of δ-phase Pu will be changed (e.g., hardening and embrittlement ) since the α decay of plutonium will produce helium nuclei that aggregate to form helium bubbles. The study of helium bubbles behaviors (e.g., nucleation, growth and mergence) in δ-phase Pu is always the focus and difficulty of plutonium self-irradiation aging problem . At present, it is difficult to carry out experimental studies on the evolution of helium bubble behavior in the radioactive δ-phase Pu. Simulation study is necessary. In this program we plan to employ molecular dynamics method to explore and compare both growth mechanisms of helium bubbles in the case of self-irradiation and loading. We plan to investigate effects of temperature, pressure and loading on the growth mechanism of helium bubbles, and the interactions between dislocation and helium bubbles, helium bubble and helium bubble. Finally we will obtain the mechanism on the helium bubble's growth and mergence, laying the foundation for establishing a simulation model of δ-phase Pu based on micro-structure evolution.

δ钚在武器和核电系统中有着重要的应用价值。由于钚元素会发生α衰变而产生氦核并聚集形成氦泡，δ钚的力学性能受到氦泡行为的影响（比如硬化和脆化）。δ钚中氦泡的形核、长大、合并等行为的研究一直是钚自辐照老化问题的焦点和难点。目前，实验上很难开展放射性δ钚中氦泡行为演化的研究，需要借助模拟方法。 本项目拟采用分子动力学模拟方法，对自辐照和加载这两种情况下的氦泡生长机制进行探索和比较，考虑温度、压力、载荷对氦泡生长机制的影响，以及位错与氦泡、氦泡与氦泡的相互作用，获得δ钚中氦泡的长大、合并等行为的机理性认识，为建立基于微结构演化的δ钚力学性能计算模型奠定基础。

δ钚镓合金是一种重要的核材料，由于其具有自辐照老化特性，会产生氦泡并影响其力学性能。本项目针对δ-Pu-Ga合金中的氦泡行为，基于并行分子动力学计算方法，采用修正嵌入原子多体势，模拟了钚镓合金中氦泡的长大、合并及变形过程，对自辐照和加载这两种情况下的氦泡长大/变形机制进行了探索和比较，考察了氦泡在不同温度和内压条件下对氦泡长大的影响，以及位错与氦泡、氦泡与氦泡、表面与氦泡的相互作用，获得了对钚镓合金中氦泡长大、合并、变形等行为的机理性认识，可为Pu-Ga合金氦泡行为研究提供借鉴和参考。