当前位置: X-MOL 学术Acta Mater. › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Enhancement of fatigue resistance by overload-induced deformation twinning in a CoCrFeMnNi high-entropy alloy
Acta Materialia ( IF 8.3 ) Pub Date : 2020-12-01 , DOI: 10.1016/j.actamat.2020.10.016
Tu-Ngoc Lam , Soo Yeol Lee , Nien-Ti Tsou , Hung-Sheng Chou , Bo-Hong Lai , Yao-Jen Chang , Rui Feng , Takuro Kawasaki , Stefanus Harjo , Peter K. Liaw , An-Chou Yeh , Ming-Jun Li , Ren-Fong Cai , Sheng-Chuan Lo , E-Wen Huang

Abstract We examined fatigue-crack-growth behaviors of CoCrFeMnNi high-entropy alloys (HEAs) under as-fatigued and tensile-overloaded conditions using neutron-diffraction measurements coupled with diffraction peak-profile analyses. We applied both high-resolution transmission electron microscopy (HRTEM) and neutron-diffraction strain mapping for the complementary microstructure examinations. Immediately after a single tensile overload, the crack-growth-retardation period was obtained by enhancing the fatigue resistance, as compared to the as-fatigued condition. The combined mechanisms of the overload-induced larger plastic deformation, the enlarged compressive residual stresses and plastic-zone size, the crack-tip blunting ahead of the crack tip, and deformation twinning governed the pronounced macroscopic crack-growth-retardation behavior following the tensile overload. A remarkable fracture surface of highly-periodic serrated features along the crack-propagation direction was found in the crack-growth region immediately after the tensile overload. Moreover, a transition of plastic deformation from planar dislocation slip-dominated to twinning-dominated microstructures in the extended plastic zone was clearly observed at room temperature in the overloaded condition, in accordance with the simulated results by a finite element method (FEM). The above tensile overload-induced simultaneously combined effects in the coarse-grained CoCrFeMnNi shed light on the improvement of fatigue resistance for HEAs applications.

中文翻译:

CoCrFeMnNi高熵合金超载变形孪晶增强抗疲劳性

摘要 我们使用中子衍射测量结合衍射峰剖面分析研究了 CoCrFeMnNi 高熵合金 (HEA) 在疲劳和拉伸过载条件下的疲劳裂纹扩展行为。我们将高分辨率透射电子显微镜 (HRTEM) 和中子衍射应变图应用于互补的微观结构检查。与疲劳状态相比,在单次拉伸过载后立即通过增强抗疲劳性获得裂纹扩展延迟期。过载引起较大塑性变形、残余压应力和塑性区尺寸增大、裂纹尖端先于裂纹尖端变钝的综合机制,和变形孪生控制了拉伸过载后显着的宏观裂纹扩展延迟行为。在拉伸过载后立即在裂纹扩展区域发现了沿裂纹扩展方向具有高周期性锯齿状特征的显着断裂表面。此外,根据有限元法 (FEM) 的模拟结果,在室温下,在过载条件下,可以清楚地观察到塑性变形从平面位错滑移主导向双晶主导的延伸塑性区微观结构的转变。上述拉伸过载在粗晶 CoCrFeMnNi 中同时引起的综合效应揭示了 HEAs 应用的抗疲劳性的提高。在拉伸过载后立即在裂纹扩展区域发现了沿裂纹扩展方向具有高度周期性锯齿状特征的显着断裂表面。此外,根据有限元法 (FEM) 的模拟结果,在室温下,在过载条件下,可以清楚地观察到塑性变形从平面位错滑移主导向双晶主导的延伸塑性区微观结构的转变。上述拉伸过载在粗晶 CoCrFeMnNi 中同时引起的综合效应揭示了 HEAs 应用的抗疲劳性的提高。在拉伸过载后立即在裂纹扩展区域发现了沿裂纹扩展方向具有高度周期性锯齿状特征的显着断裂表面。此外,根据有限元法 (FEM) 的模拟结果,在室温下,在过载条件下,可以清楚地观察到塑性变形从平面位错滑移主导向双晶主导的延伸塑性区微观结构的转变。上述拉伸过载在粗晶 CoCrFeMnNi 中同时引起的综合效应揭示了 HEAs 应用的抗疲劳性的提高。根据有限元法 (FEM) 的模拟结果,在室温下,在过载条件下,可以清楚地观察到塑性变形从平面位错滑移主导向双晶主导的延伸塑性区微观结构的转变。上述拉伸过载在粗晶 CoCrFeMnNi 中同时引起的综合效应揭示了 HEAs 应用的抗疲劳性的提高。根据有限元法 (FEM) 的模拟结果,在室温下,在过载条件下,可以清楚地观察到塑性变形从平面位错滑移主导向孪晶主导的延伸塑性区微观结构的转变。上述拉伸过载在粗晶 CoCrFeMnNi 中同时引起的综合效应揭示了 HEAs 应用的抗疲劳性的提高。
更新日期:2020-12-01
down
wechat
bug