Short-range-ordering strengthening and the evolution of dislocation-nucleation modes in an Fe40Mn20Cr20Ni20 high-entropy alloy
Short-range-ordering strengthening and the evolution of dislocation-nucleation modes in an Fe40Mn20Cr20Ni20 high-entropy alloy
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DOI：
10.1016/j.msea.2023.145038
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发表时间：
2023-04
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与均匀状态下的Fe40Mn20Cr20Ni20合金相比，高温时效后的Fe40Mn20Cr20Ni20合金具有更高的初塑性强度，这归因于局部成分波动导致的短程有序(SRO)的产生。基于不同加载速率下的纳米压痕结果，揭示了SRO效应下均匀和非均匀位错成核模式的演化趋势。在高加载速率引起的高溶摩擦应力和SROS引起的共格应变场的作用下，位错形核的临界剪应力增大。此外，随着加载速率的增加，均匀样品中异质形核的几率增加，而时效样品中的异质形核几率则相反。从位错成核位的分布来看，这种相反的趋势可以通过假设可激活区的扩展阻力来很好地解释。总之，本工作揭示了SRO对位错成核模式的关键作用，为定量研究SRO及其强化效应奠定了基础。
Compared with the Fe40Mn20Cr20Ni20high-entropy alloy in a homogenized state, it has higher incipient plastic strength after high-temperature aging, which is attributed to the generation of short-range orderings (SROs) caused by the local composition fluctuations. Based on nanoindentation results at different loading rates, the evolution trends of homogeneous and heterogeneous dislocation-nucleation modes under the effect of SROs are revealed. Under the action of the high-solution friction stress, which is caused by the high loading rate, and coherency-strain field, which is caused by SROs, the critical shear stress of the dislocation nucleation increases. Furthermore, with the increase of the loading rate, the probability of heterogeneous nucleation in homogenized samples increases, while that in aged samples is the opposite. From the perspective of the distribution of dislocation-nucleation sites, this opposite trend can be well explained by assuming the spreading resistance of an activatable region. In short, the present work reveals the pivotal role of SROs on dislocation-nucleation modes and paves the way for the quantitative study concerning SROs and their strengthening effects.