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Room-temperature deformation of single crystals of the sigma-phase compound FeCr with the tetragonal D8b structure investigated by micropillar compression
Acta Materialia ( IF 9.4 ) Pub Date : 2023-03-04 , DOI: 10.1016/j.actamat.2023.118829
Kyosuke Kishida, Masaomi Okutani, Hirotaka Suzuki, Haruyuki Inui, Martin Heilmaier, Dierk Raabe

The deformation behavior of single crystals of the sigma-phase compound FeCr with the tetragonal D8b structure has been investigated by micropillar compression at room temperature as a function of crystal orientation and specimen size. In spite of the repeatedly reported brittleness, plastic flow is observed at room temperature for all loading axis orientations tested. Three slip systems, {100}[001], {100}<010> and {111}<01¯1> are newly identified to be operative at room temperature depending on the loading axis, in addition to {110}[001] slip we previously identified. The CRSS values for all the identified slip systems are very high exceeding 1.3 GPa and decrease with increasing specimen size, following an inverse power-law relationship with a very small power-law exponent. Similarly to {110}[001] slip, {100}[001] slip is confirmed to be carried by the motion of [001] zonal dislocations through atomic-resolution scanning transmission electron microscopy imaging of their core structures. <010> dislocations gliding on {100} are confirmed to dissociate into two collinear partial dislocations, while <01¯1> dislocations gliding on {111} to dissociate into three collinear partial dislocations. The fracture toughness values estimated by micro-cantilever bend tests of chevron-notched micro beam specimens are indeed very low, 1.6∼1.8 MPa·m1/2 (notch plane // (001) and (100)), indicating significant brittleness of sigma FeCr.



中文翻译:

通过微柱压缩研究具有四方 D8b 结构的 σ 相化合物 FeCr 单晶的室温变形

具有四方 D8 b结构的 σ 相化合物 FeCr 单晶的变形行为已通过微柱压缩在室温下作为晶体取向和试样尺寸的函数进行了研究。尽管反复报告了脆性,但在室温下观察到所有测试的加载轴方向的塑性流动。三个滑动系统,{100}[001]、{100}<010> 和 {111}<01个¯1> 除了我们之前确定的 {110}[001] 滑动之外,新确定在室温下根据加载轴可操作。所有已识别的滑移系统的 CRSS 值都非常高,超过 1.3 GPa,并且随着样本尺寸的增加而降低,遵循具有非常小的幂律指数的反幂律关系。类似于 {110}[001] 滑移,{100}[001] 滑移被证实是由 [001] 带状位错的运动携带的,通过其核心结构的原子分辨率扫描透射电子显微镜成像。<010> 在 {100} 上滑动的位错被证实分解成两个共线的部分位错,而 <01个¯1> 位错在 {111} 上滑动,分解成三个共线的部分位错。通过人字形缺口微梁试样的微悬臂梁弯曲试验估计的断裂韧性值确实非常低,为 1.6∼1.8 MPa·m 1/2(缺口平面//(001)和(100)),表明显着的脆性西格玛铁铬。

更新日期:2023-03-08
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