Abstract Simulation of lamellar boundary (γ/γ) selection during the transformation of α2’→α2+γ in γ-TiAl alloy has been investigated using an improved 3D Phase Field (PF) model, and the mechanical properties of γ/γ boundaries are evaluated by Molecular Dynamics (MD) simulation. The effects of elastic strain energy and interfacial energy difference among different types of γ/γ interfaces on the occurrence frequencies of the three types of γ/γ boundaries (i.e., true twin (TT), pseudo-twin (PT) and ordered domain (OD)) have been studied. It is found that the boundary fraction of TT increases with increasing elastic strain energy or increasing interfacial energy difference among γ/γ interfaces. Besides TT, the elastic interaction also favors OD while PT is suppressed. The relative fractions of PT and OD could be effectively controlled by elastic strain energy. Furthermore, the frequency of PT or OD can also be adjusted by their interface energy ratio. The simulation results well explain the phenomenon that boundary frequencies via experimental statistics deviate from those under random distribution without interface selection. It can also be found that one-twin-dominant zones (OTDZ) can be induced by higher elastic strain energy and larger interface energy difference among different γ/γ boundaries through the merging of adjacent small clusters with the same γ/γ boundary type under the premise of correlated and sympathetic nucleation. Through MD simulation, it is found that the strengths of the configurations with true twin boundary (TTB) and ordered domain boundary (ODB) are almost the same, while the strength of that with pseudo-twin boundary (PTB) is relatively low. The order of plasticity of the configurations with three types of γ/γ interfaces is ODB > TTB > PTB.

中文翻译：

---

γ-TiAl合金中γ/γ界面的选择与力学评价

摘要 使用改进的 3D 相场 (PF) 模型研究了 γ-TiAl 合金中 α2'→α2+γ 转变过程中层状边界 (γ/γ) 选择的模拟，γ/γ 边界的力学性能为通过分子动力学 (MD) 模拟评估。不同类型γ/γ界面之间的弹性应变能和界面能差异对三种γ/γ边界（即真孪晶（TT）、伪孪晶（PT）和有序域（ OD)) 进行了研究。发现TT的边界分数随着弹性应变能的增加或γ/γ界面之间界面能差的增加而增加。除了 TT，弹性相互作用也有利于 OD，而 PT 受到抑制。弹性应变能可以有效控制 PT 和 OD 的相对分数。此外，PT 或 OD 的频率也可以通过它们的界面能比进行调整。模拟结果很好地解释了通过实验统计的边界频率与没有界面选择的随机分布下的边界频率偏离的现象。还可以发现，通过在不同的 γ/γ 边界之间通过合并具有相同 γ/γ 边界类型的相邻小簇，可以通过更高的弹性应变能和更大的界面能差异来诱导单孪主导区（OTDZ）。相关和交感成核的前提。通过MD模拟，发现真孪晶边界（TTB）和有序域边界（ODB）的构型强度几乎相同，而伪孪晶边界（PTB）的强度相对较低。三种 γ/γ 界面构型的可塑性顺序为 ODB > TTB > PTB。