Effects of temperature on structure and mobility of the 〈1 0 0〉 edge dislocation in body-centred cubic iron
Effects of temperature on structure and mobility of the 〈1 0 0〉 edge dislocation in body-centred cubic iron
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DOI：
10.1016/j.actamat.2009.12.033
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发表时间：
2010-04
期刊：
影响因子：
9.4
通讯作者：
D. Terentyev;Y. Osetsky;D. Bacon
中科院分区：
文献类型：
--
作者：
D. Terentyev;Y. Osetsky;D. Bacon
体心立方（bcc）金属在变形过程中，通过b=1/2 < 111 >的位错相互作用，形成了Burgers向量b= < 100 >的位错段。这种片段也可由辐照bcc金属中的位错和位错环之间的反应产生。这些片段在滑移位错上产生的障碍物阻力由它们的迁移率控制，而迁移率又由它们核心的原子结构决定。本文利用三种不同的原子间电位对α-铁原子进行了原子尺度的计算机模拟，研究了直线< 100 >边缘位错的核心结构。在低温下，位错有一个非平面核，由两个1/2 < 111 >的分数位错组成，原子位错分布在向主滑动面倾斜的平面上。升高的温度改变了这种核心结构，从而降低了< 100 b>位错滑动的临界应用剪应力。结果表明，< 100 >边缘位错对温度或外加应力的响应决定了移动位错与1/2 < 111 >位错环之间发生的特定反应途径。本文讨论并举例说明了这对未辐照和辐照铁素体材料塑性流动的影响。
Dislocation segments with Burgers vector b=〈100〉 are formed during deformation of body-centred-cubic (bcc) metals by the interaction between dislocations with b=1/2〈111〉. Such segments are also created by reactions between dislocations and dislocation loops in irradiated bcc metals. The obstacle resistance produced by these segments on gliding dislocations is controlled by their mobility, which is determined in turn by the atomic structure of their cores. The core structure of a straight 〈100〉 edge dislocation is investigated here by atomic-scale computer simulation for α-iron using three different interatomic potentials. At low temperature the dislocation has a non-planar core consisting of two 1/2〈111〉 fractional dislocations with atomic disregistry spread on planes inclined to the main glide plane. Increasing temperature modifies this core structure and so reduces the critical applied shear stress for glide of the 〈100〉 dislocation. It is concluded that the response of the 〈100〉 edge dislocation to temperature or applied stress determines specific reaction pathways occurring between a moving dislocation and 1/2〈111〉 dislocation loops. The implications of this for plastic flow in unirradiated and irradiated ferritic materials are discussed and demonstrated by examples.