Effect of Dislocation Character on the CRSS
Effect of Dislocation Character on the CRSS
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DOI：
10.1016/j.actamat.2023.118982
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发表时间：
2023-05
期刊：
影响因子：
9.4
通讯作者：
O. Celebi;A. Mohammed;H. Sehitoglu
中科院分区：
文献类型：
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作者：
O. Celebi;A. Mohammed;H. Sehitoglu
晶体结构材料的屈服强度是一种基本的力学性能，主要由位错滑移的临界应力决定。实验研究表明，位错的性质(螺位错、刃位错或位错混合位错)对临界分辨剪应力(CRSS)有很大影响。现有的CRSS预测的解析方法假定滑移面为原子行描述，并且不考虑每个离散晶格位置的Wigner-Seitz(WS)晶胞面积。此外，由于没有充分考虑材料的弹性各向异性和假定的位错“芯-宽度”水平，因此无法进行正确的CRSS测定。这项研究提出了一种应用于面心立方(FCC)材料的预测模型，解决了在预测解离位错的滑动应力方面的这些缺陷。由位错核的连续应变能(E-S T、R、A、I、N)和原子失配能(E、M、I、S、F、T)组成的总能量的最小化严格确定了位错核的宽度。E-S T R A I N是用全各向异性EShelby-Stroh公式计算位错应变场得到的。由滑移面的广义层错能图确定了E M I S F I T。以前的E-M-I-S F-I-T计算仅限于“简单”立方晶格中的滑移行，而不代表面心立方晶体中的滑移面。所建立的模型用于对多种金属材料的CRSS进行预测，修正了对实验CRSS水平的高估。结果揭示了CRSS对位错特性的显著依赖性，揭示了GSFE参数对CRSS的非平凡依赖性。因此，这项研究解决了结构材料结构-性能预测中的一个主要空白。
The yield strength of a crystalline structural material is a fundamental mechanical property predominantly governed by the critical stress for dislocation slip. This Critical Resolved Shear Stress (CRSS) is strongly influenced by the character of the dislocation (eg, screw, edge, or mixed) as shown in previous experimental studies. Existing analytical approaches for CRSS prediction assume an atomic row description of the slip plane and do not account for Wigner-Seitz (WS) cell area at each discrete lattice site. Further, inadequate consideration of the material's elastic anisotropy and the presumed dislocation “core-width” level precludes correct CRSS determination. This study proposes a predictive model applied to Face Centered Cubic (FCC) materials addressing these shortcomings in predicting glide stress of a dissociated dislocation. The core-width is rigorously determined from the minimization of total energy comprised of continuum strain energy (E S T R A I N) and atomistic misfit energy (E M I S F I T) of the dislocation's core. The E S T R A I N is obtained from dislocation strain-fields calculated using the fully-anisotropic Eshelby-Stroh formalism. The E M I S F I T is determined from the Generalized Stacking Fault Energy (GSFE) landscape of the slip plane. Previous E M I S F I T calculations are restricted to slipped rows in ‘simple’cubic lattices which do not represent the slip-planes in FCC crystals. The developed model is used to predict CRSS for a wide range of metallic materials correcting the overprediction of experimental CRSS levels. The results unveiled the remarkable dependence of CRSS on the dislocation character, revealing the non-trivial dependence on GSFE parameters. Thus, this study addresses a major void in structure-property prediction for structural materials.