Role of local chemical fluctuations in the shock dynamics of medium entropy alloy CoCrNi

Xie, Zhuocheng; Jian, Wu-Rong; Xu, Shuozhi; Beyerlein, Irene J.; Zhang, Xiaoqing; Wang, Zhihua; Yao, Xiongliang

doi:10.1016/j.actamat.2021.117380

Cited by 76 publications

(14 citation statements)

References 91 publications

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“…同时总结了利用分子动力学方法可以研究的相关材料冲击问题, 如材料的冲击波结构、Hugoniot弹性极限(HEL)、冲击 Hugoniot关系、冲击诱导相变、冲击诱导熔化、冲击变形图、破坏等. 利用分子动力学方法, Zhao等 [20] 研究了BCC结构TiZrNb和 NiCoFeTi高熵合金的冲击响应, 发现了具有高稳定性的异常扩展刃型位错结构, 其可以促进更快的位错运动, 从而阻止变形孪晶的早期成核. Xie等 [21] 和Jian等 [22] 对 [23] 和 Thürmer 等 [24] 研究了纳米结构高熵合金的冲击破坏现象, 与单晶高熵合金相比, 纳米晶高熵合金的破坏强度明显降低, 在冲击压缩和释放(release)的过程中存在大量的堆垛层错、孪晶和位错.…”

Section: 作为研究材料微观结构演化的重要手段分子unclassified

Molecular dynamics study of temperature effects on shock response and plastic deformation mechanism of CoCrFeMnNi high-entropy alloys

Wen¹,

Tao²

2022

Acta Phys. Sin.

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High-entropy alloys have broad application prospects in aviation, aerospace, military and other fields due to their excellent mechanical properties. Temperature is an important external factor affecting the shock response of high-entropy alloys. In this paper, we investigate the effects of temperature on the shock response and plastic deformation mechanism of CoCrFeMnNi high-entropy alloys by using molecular dynamics method. The effects of temperature on the atomic volume and the radial distribution function of CoCrFeMnNi high-entropy alloy are studied. Then, the piston method is used to generate shock waves in the sample to study the shock response of CoCrFeMnNi high-entropy alloy. We observe the evolution of atomic-scale defects during the shock compression by the polyhedral template matching method. The results show that the shock pressure, the shock wave propagation velocity, and the rising of shock-induced temperature all decrease with the initial temperature increasing. For example, when piston velocity Up = 1.5 km/s, the shock pressure at an initial temperature of 1000 K decreases by 6.7% in comparison with that at 1 K. Moreover, the shock Hugoniot elastic limit decreases linearly with the increase of temperature. The Hugoniot Up– Us curve of CoCrFeMnNi HEA in the plastic stage can be linearly fitted by the formula Us = c0 +sUp, where c0 decreases with temperature increasing. As the shock intensity increases, the CoCrFeMnNi high-entropy alloy undergoes complex plastic deformation, including dislocation slip, phase transformation, deformation twinning, and shock-induced amorphization. At relatively high initial temperature, disordered clusters appear inside CoCrFeMnNi HEA, which together with the BCC structure transformed from FCC and disordered structure are significant dislocation nucleation sources. Compared with other elements, Mn element accounts for the largest proportion (25.4%) in disordered cluster. Owing to the large atomic volume and potential energy, large lattice distortion and local stress occur around the Mn-rich element, which makes a dominant contribution to shock-induced plastic deformation. At high temperatures, the contribution of Fe element to plastic deformation is as important as that of Mn element. The research results are conducive to understanding the shock-induced plasticity and deformation mechanisms of CoCrFeMnNi high-entropy alloys in depth.

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Section: 作为研究材料微观结构演化的重要手段分子unclassified

Molecular dynamics study of temperature effects on shock response and plastic deformation mechanism of CoCrFeMnNi high-entropy alloys

Wen¹,

Tao²

2022

Acta Phys. Sin.

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“…However, despite this understanding of dynamic failure, the detailed microscopic mechanisms, particularly the linkage between local microstructure and the dynamic behavior of materials, remain unclear. Recent molecular dynamics (MD) simulations indicate that the local chemical fluctuation can markedly affect both dislocation activities ( 46 ) and the void dynamics in HEAs ( 47 ) and, hence, influence their impact resistance. Further understanding of the underlying material physics would certainly aid the design of impact-resistant materials, which has been an ongoing challenge for many applications including vehicle crash safety, penetration protection, and aerospace engineering.…”

Section: Introductionmentioning

confidence: 99%

Deformation and failure of the CrCoNi medium-entropy alloy subjected to extreme shock loading

et al. 2023

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The extraordinary work hardening ability and fracture toughness of the face-centered cubic (fcc) high-entropy alloys render them ideal candidates for many structural applications. Here, the deformation and failure mechanisms of an equiatomic CrCoNi medium-entropyalloy (MEA) were investigated by powerful laser-driven shock experiments. Multiscale characterization demonstrates that profuse planar defects including stacking faults, nanotwins, and hexagonal nanolamella were generated during shock compression, forming a three-dimensional network. During shock release, the MEA fractured by strong tensile deformation and numerous voids was observed in the vicinity of the fracture plane. High defect populations, nanorecrystallization, and amorphization were found adjacent to these areas of localized deformation. Molecular dynamics simulations corroborate the experimental results and suggest that deformation-induced defects formed before void nucleation govern the geometry of void growth and delay their coalescence. Our results indicate that the CrCoNi-based alloys are impact resistant, damage tolerant, and potentially suitable in applications under extreme conditions.

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“…In recent years, detectable levels of SRO have been reported in both FCC MPEAs such as CoCrNi [13,14] and CoNiV [15] as well as the BCC RMPEAs such as HfNbZr [16]. Supporting calculations of SRO in MPEAs have been provided via density functional theory (DFT) and hybrid Monte Carlo (MC)/MD simulations, where temperature is used to adjust the extent and severity of SRO [17][18][19][20][21][22][23][24]. DFT calculations have shown that SRO in MoNbTaW RMPEA reduces the variation in the dislocation core properties, while have little effect on their core energies [25].…”

Section: Introductionmentioning

confidence: 99%

Multi-scale Investigation of Chemical Short-Range Order and Dislocation Glide in the MoNbTi and TaNbTi Refractory Multi-Principal Element Alloys

Fey¹,

Li²,

Hu³

et al. 2022

Preprint

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Refractory multi-principal element alloys (RMPEAs) are promising materials for high-temperature structural applications. Here, we investigate the role of chemical short-range ordering (CSRO) on dislocation glide in two model RMPEAs -TaNbTi and MoNbTi -using a multi-scale modeling approach. A highly accurate machine learning interatomic potential was developed for the Mo-Ta-Nb-Ti system and used to demonstrate that MoNbTi exhibits a much greater degree of SRO than TaNbTi and the local composition has a direct effect on the unstable stacking fault energies (USFE). From mesoscale phase-field dislocation dynamics simulations, we find that increasing SRO leads to higher mean USFEs, thereby increasing the stress required for dislocation glide. The gliding dislocations experience significant hardening due to pinning and depinning caused by random compositional fluctuations, with higher SRO decreasing the degree of USFE dispersion and hence, amount of hardening. Finally, we show how the morphology of an expanding dislocation loop is affected by the applied stress, with higher SRO requiring higher applied stresses to achieve smooth screw dislocation glide.

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Role of local chemical fluctuations in the shock dynamics of medium entropy alloy CoCrNi

Cited by 76 publications

References 91 publications

Molecular dynamics study of temperature effects on shock response and plastic deformation mechanism of CoCrFeMnNi high-entropy alloys

Molecular dynamics study of temperature effects on shock response and plastic deformation mechanism of CoCrFeMnNi high-entropy alloys

Deformation and failure of the CrCoNi medium-entropy alloy subjected to extreme shock loading

Multi-scale Investigation of Chemical Short-Range Order and Dislocation Glide in the MoNbTi and TaNbTi Refractory Multi-Principal Element Alloys

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