TEM observation was conducted during Ni&Hedual-beam irradiation to monitor the evolution of dislocation loops accompanied by He bubbles in the Ni-based alloy GH3535. Two distinct evolutions of dislocation loops, driven by residual stresses, were observed within the monitored grains. Hence, molecular dynamics (MD) simulations were employed to reveal the effects of stress magnitude and direction on loop evolution, including size, number density, type and variation. The simulations revealed that the presence of compressive stress reduced the formation energy of perfect dislocation loops, thus promoting their formation. Stress state was found to influence the preferential orientation of the loops, and compressive stress resulted in a decreased number density of dislocation loops but an increase in their size. This establishes a clear relationship between stress state and magnitude and the evolution of dislocation loops during ion beam irradiation. Additionally, the nature and characteristics of dislocation loops were quantified to explore the effects of He concentrations on their evolution. The higher He concentration not only promotes the nucleation of dislocation loops, leading to their higher number density, but also facilitates the unfaulting evolution by increasing the stacking fault energy (SFE). Moreover, the accumulation of He in the lower-He-concentration sample led to the growth of dislocation loops in multiple stages, explaining their nearly identical average sizes when compared to the higher-He-concentration sample.

中文翻译：

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Ni+和He+双束离子辐照下镍高温合金中应力状态和He浓度对位错环演化的影响：原位TEM观察和MD模拟


在Ni&He双束辐照过程中进行TEM观察，以监测Ni基合金GH3535中伴随He气泡的位错环的演化。在受监测的晶粒内观察到由残余应力驱动的位错环的两种不同演化。因此，采用分子动力学（MD）模拟来揭示应力大小和方向对环演化的影响，包括尺寸、数密度、类型和变化。模拟表明，压应力的存在降低了完美位错环的形成能，从而促进了它们的形成。研究发现，应力状态会影响位错环的择优取向，而压应力会导致位错环的数量密度降低，但其尺寸增加。这在离子束照射期间应力状态和大小以及位错环的演化之间建立了明确的关系。此外，还对位错环的性质和特征进行了量化，以探索 He 浓度对其演化的影响。较高的 He 浓度不仅促进位错环的成核，导致其数密度更高，而且还通过增加堆垛层错能 (SFE) 促进无断层演化。此外，He在较低He浓度样品中的积累导致了位错环在多个阶段的增长，这解释了与较高He浓度样品相比它们的平均尺寸几乎相同。