Synergistic effect of precipitation strengthening and multi-heterostructure on the improvement of strength and ductility in NbC-reinforced FeMnCoCr high entropy alloys
Synergistic effect of precipitation strengthening and multi-heterostructure on the improvement of strength and ductility in NbC-reinforced FeMnCoCr high entropy alloys
复制标题
沉淀强化和多重异质结构对 NbC 增强 FeMnCoCr 高熵合金强度和塑性提高的协同作用
DOI：
10.1016/j.msea.2022.143679
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发表时间：
2022
期刊：
影响因子：
6.4
通讯作者：
Zhaodong Wang
中科院分区：
文献类型：
--
作者：
Qi Wang;Xiaolin Li;Kaiyan Song;Xiangtao Deng;Zhaodong Wang
通过调整退火工艺参数，获得了合适的NbC增强Fe 48 Mn 30 Co 10 Cr 10 NbC（at%）高熵合金（HEA）。Nb的加入可导致静态再结晶延迟，同时，剪切带和微米尺度NbC作为形核点，导致再结晶形核的异质性，有利于多异质结构的调控。多异质结构包含超细再结晶晶粒、微米尺寸的再结晶晶粒、具有致密位错的大的未再结晶晶粒以及微米、亚微米和纳米尺寸的NbC颗粒，其中晶粒尺寸呈现双峰分布。当超细再结晶晶粒含量为41.8%（体积分数）时，试样的屈服强度为843 MPa，均匀延伸率为30.8%，具有优异的综合力学性能。高的屈服强度归因于沉淀强化和多异质结构，约为具有类似均匀延伸率的其他HEAs的1.5倍。高再结晶体积（>70%）的试样表现出三阶段加工硬化行为，加工硬化速率的提高主要与位错强化和相变诱发塑性（TRIP）效应有关。孪晶诱导塑性（TRIP）效应优先发生在粗晶中，未再结晶晶粒中较低的位错密度有利于TRIP效应的产生。这一新的多异质结构NbC增强HEA的设计策略为高性能HEA的开发提供了理论依据。·通过调整退火参数，获得了合适的NbC增强HEA多异质结构。· Nb元素导致静态再结晶延迟，有利于多异质结构的调控。·多异质结构NbC增强的HEA的屈服强度是在类似伸长率下的其他HEA的1.5倍。·通过调整不同尺寸晶粒的比例和位错密度，获得了较好的加工硬化率。
An appropriate multi-heterostructure NbC-reinforced Fe 48 Mn 30 Co 10 Cr 10 NbC (at%) high entropy alloy (HEA) was obtained by adjusting the annealing parameter. Nb addition can lead to static recrystallization retardation, additionally, shear bands and micro-sized NbC as nucleation sites led to the heterogeneous of recrystallization nucleation, which is conducive to the regulation of multi-heterostructure. The multi-heterostructure contained ultrafine recrystallized grains, micron-sized recrystallized grains, large un-recrystallized grains with dense dislocations, and micron-, submicron-, and nano-sized NbC particles, with the grain size exhibiting a bimodal distribution. The sample with 41.8% (volume fraction) ultrafine recrystallized grains exhibited excellent comprehensive mechanical properties with yield strength of 843 MPa and uniform elongation of 30.8%. The high yield strength was attributed to precipitation strengthening and multi-heterostructure, which is about 1.5 times that of other HEAs with similar uniform elongation. The samples with high recrystallization volumes (>70%) exhibited three-stage work hardening behavior, and the increase in the work hardening rate was primarily related to dislocation strengthening and the transformation induced plasticity (TRIP) effect. Twinning induced plasticity (TWIP) effect preferentially occurred in the coarse grain, and lower dislocation density in the un-recrystallized grain was beneficial to TRIP effect. This new design strategy of the multi-heterostructure NbC-reinforced HEA provides a theoretical basis for the development of high-performance HEAs. • An appropriate multi-heterostructure NbC-reinforced HEA was obtained by adjusting the annealing parameter. • Nb element leads to static recrystallization retardation, which is conducive to the regulation of multi-heterostructure. • The yield strength of the multi-heterostructure NbC-reinforced HEA is 1.5 times that of other HEAs at similar elongations. • By adjusting the proportion of grain with different sizes and dislocation density, a decent work-hardening rate was obtained.