Effect of β-stabilizer elements on stacking faults energies and ductility of α-titanium using first-principles calculations
Effect of β-stabilizer elements on stacking faults energies and ductility of α-titanium using first-principles calculations
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DOI：
10.1063/1.4966939
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发表时间：
2016-11-07
影响因子：
3.2
通讯作者：
Srinivasan, S. G.
中科院分区：
文献类型：
--
作者：
Salloom, R.;Banerjee, R.;Srinivasan, S. G.
用第一性原理计算方法研究了W、Mo、V、Ta、Nb五种常见的β稳定替代元素对α-Ti层错能的影响。用含360个原子的超晶胞测定了不同浓度β稳定剂在断层面上的广义层错能(GSFE)曲线。确定了具有稳定(伽马(SF))和不稳定(伽马(USF))层错和孪生断层能的基底和棱柱滑移系。所有合金元素都降低了钛的基面滑移和棱柱滑移的层错能。当滑移面上V、Ta、Nb含量较高(25at.%)时，钛中的基面滑移比棱柱滑移更有利。Ti-Mo和Ti-W系统的GSFE曲线也显示出明显的向沿-lt；01(1)方向的较大剪切变形应变的移动，这是由于Ti与这两个元素之间的成键性质的改变。用S的伽马和美国的伽马比来估计塑性的赖斯准则表明，所有的合金化元素都可能改善α-钛的塑性，其中Ti-25at.%Nb表现出最好的塑性行为。然而，根据TAdmor和Bernstein模型，所考虑的所有合金元素都不能改善部分位错发射或孪晶倾向，尽管降低了α-Ti和的层错能。因此，需要一个更好的经验模型来估计合金化对HCP金属延展性的影响，该模型包含了合金化时定向结合特性的变化。由AIP出版公司出版。
The effect of W, Mo, V, Ta, and Nb, five common beta-stabilizing substitutional elements, on alpha-Ti stacking fault energy has been studied using first principle calculations. The generalized stacking fault energy (GSFE) curves have been determined for different concentrations of beta-stabilizers at the fault plane using supercells with up to 360 atoms. Both basal and prismatic slip systems with the stable (gamma(SF)) and unstable (gamma(USF)) stacking faults and twinning fault energies were determined. All the alloying elements reduce the stacking fault energy for Ti for both basal and prismatic slip. At higher concentration of 25 at.% of V, Ta, and Nb at the slip plane, the basal slip becomes more favorable than the prismatic slip in Ti. Ti-Mo and Ti-W systems also show a significant shift in the GSFE curve towards a higher shear deformation strain along < 01 (1) over bar0 > due to the change in bond character between Ti and those two elements. Using Rice criterion, which employs gamma(S)/gamma(USF) ratio to estimate ductility, we show that all the alloying elements likely improve the ductility of alpha-Ti with Ti-25 at.% Nb exhibiting the most ductile behavior. However, according to the Tadmor and Bernstein model, all the alloying elements considered here do not improve the partial dislocation emission or the twinning propensity in spite of decreasing the stacking fault energies for alpha-Ti and. Hence, a better empirical model that incorporates changes in the character of directional bonding upon alloying is needed to estimate how alloying influences ductility in hcp metals. Published by AIP Publishing.