Dynamic deformation behavior and microstructure evolution of CoCrNiMox medium entropy alloys
Dynamic deformation behavior and microstructure evolution of CoCrNiMox medium entropy alloys
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DOI：
10.1016/j.msea.2021.142048
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发表时间：
2021-09-13
期刊：
影响因子：
6.4
通讯作者：
Song, Min
中科院分区：
文献类型：
--
作者：
Li, Na;Chen, Wentian;Song, Min
本文研究了一系列Mo掺杂CoCrNi中熵合金在相似高应变率下的动态响应，利用分离式霍普金森压杆（SHPB）研究了CoCrNiMox（x = 0，0.1，0.2）合金的热稳定性。我们发现，随着Mo量从0增加到0.2，屈服强度几乎翻了一番，从类似于450到类似于800 MPa，在这样的高应变速率。详细的显微镜研究表明，从固溶和沉淀强化，以及高的加工硬化率，通过微带状和纳米孪晶/堆叠故障，有助于提高强度和更好的加工硬化能力。在动态压缩后，与更多的Mo的样品被发现有较高的位错密度和更频繁的纳米孪晶/层错事件。这表明Mo在超快塑性流动期间在位错积累（平面滑移）和位错解离（堆垛层错能）两者中起关键作用，这赋予Mo-0.2合金在冲击保护中的应用潜力。
In this work, the dynamic response at a similar high strain rate of a series of Mo-doped CoCrNi medium entropy alloys, i.e., CoCrNiMox (x = 0, 0.1, 0.2), was investigated via a split Hopkinson pressure bar (SHPB). We found that with the Mo amount increasing from 0 to 0.2, the yield strength nearly doubles, from similar to 450 to similar to 800 MPa, under such a high strain rate. Detailed microscopy investigations revealed that the strengthening from solid solution and precipitation, together with the high work hardening rate via micro-banding and nano-twinning/stacking faulting, contribute to strength increment and better work hardening ability. After dynamic compression, the sample with the more Mo was found to have the higher dislocation density and the more frequent nanotwin/stacking fault events. This suggests that Mo plays a critical role in both dislocation accumulation (planar slip) and dislocation dissociation (stacking fault energy) during the ultra-fast plastic flow, which endows the Mo-0.2 alloy a potential for application in impact protection.