Unveiling dislocation characteristics in Ni3Al from stacking fault energy and ideal strength: A first-principles study via pure alias shear deformation
Unveiling dislocation characteristics in Ni3Al from stacking fault energy and ideal strength: A first-principles study via pure alias shear deformation
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DOI：
10.1103/physrevb.101.024102
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发表时间：
2020-01
影响因子：
3.7
通讯作者：
S. Shang;John D. Shimanek;S. Qin;Yi Wang;A. Beese;Zi-kui Liu
中科院分区：
文献类型：
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作者：
S. Shang;John D. Shimanek;S. Qin;Yi Wang;A. Beese;Zi-kui Liu
铝化镍（Ni 3Al）是一种重要的材料，用于许多应用，特别是当用作高温镍基高温合金中的强化成分时。尽管如此，关于其机械性能（如强度、塑性、蠕变、疲劳和断裂）的信息很少。在目前的工作中，基于第一性原理的纯混叠剪切变形已被应用于使用预测的层错能（即，γ面）和理想剪切强度（τIS）。结果包括1/2[1 <$10]位错在{111}面上分裂成两个Shockley分位错的直接证据，这进一步得到了复层错能γCSF和反相界能γ APB 111的等价性的支持。利用τIS和弹性性质对Peierls应力的估计表明Ni中刃位错和Ni 3Al中螺位错的普遍存在，这与关于刃位错在fcc金属晶体变形的第一阶段中占主导地位以及Ni 3Al中与螺位错相关的屈服强度异常的实验观察一致。计算结果进一步指出，虽然超晶格本征层错和APB 001的平面能最低，但由于其低能势垒，CSF和APB 111很容易通过剪切作用形成.通过Ni 3Al的情况下，目前的工作表明，纯别名剪切方法不仅是计算效率高，但也提供了有价值的洞察剪切相关属性的性质。
Nickel aluminide (Ni3Al) is an important material for a number of applications, especially when used as a strengthening constituent in high-temperature Ni-based superalloys. Despite this, there is minimal information on its mechanical properties such as strength, plasticity, creep, fatigue, and fracture. In the present work, a first-principles based pure alias shear deformation has been applied to shed light on dislocation characteristics in Ni3Al using the predicted stacking fault energy (i.e., the γ surface) and ideal shear strength (τIS). Results include direct evidence for the splitting of a 1/2[1̄10] dislocation into two Shockley partials on the {111} plane, which is further supported by the equivalence of the complex stacking fault (CSF) energy γCSF and the antiphase boundary (APB) energy γAPB111. Estimates of the Peierls stresses using τIS and elastic properties suggest the prevalence of edge dislocations in Ni and screw dislocations in Ni3Al, agreeing with experimental observations regarding the dominance of edge dislocations in the first stage of crystal deformation in fcc metals and the yield-strength anomaly related to screw dislocations in Ni3Al. The present calculations further point out that the CSF and APB111 are easily formed by shear due to the low-energy barriers, although the lowest planar energies are for the superlattice intrinsic stacking fault and the APB001. Through the case of Ni3Al, the present work demonstrates that the pure alias shear methodology is not only computationally efficient but also provides valuable insight into the nature of shear-related properties.