Ti exhibits complex plastic deformation controlled by active dislocation and twinning systems. Understandings on dislocation cores and twin interfaces are currently not complete or quantitative, despite extensive experimental and simulation studies. Here, we determine the dislocation core, twin, and crack properties in both HCP and BCC Ti using a Deep Potential (DP), DFT and linear elastic fracture mechanics. We compute the core structures, critical resolved shear stresses and mobilities of the $〈\mathbf{a}〉$ , $〈\mathbf{c}+\mathbf{a}〉$ , $〈\mathbf{c}〉$ dislocations in HCP and the $〈111〉/2$ dislocations in BCC Ti. The $〈\mathbf{a}〉$ slip consists of slow core migration on pyramidal-I planes and fast migration on prism-planes, and is kinetically limited by cross-slips among them. This behaviour is consistent with “locking–unlocking” phenomena in TEM and is likely an intrinsic property. Large-scale DFT calculations provide a peek at the screw $〈\mathbf{c}+\mathbf{a}〉$ core and glide behaviour, which is further quantified using DP-Ti. The screw $〈\mathbf{c}+\mathbf{a}〉$ is unstable on pyramidal-II planes. The mixed $〈\mathbf{c}+\mathbf{a}〉$ is nearly sessile on pyramidal-I planes, consistent with observations of long dislocations in this orientation. The edge and mixed $〈\mathbf{c}+\mathbf{a}〉$ are unstable against a pyramidal-to-basal (PB) transition and become sessile at high temperatures, corroborate the difficulties in $〈\mathbf{c}〉$ -axis compression of Ti. Cracks on basal planes are predicted and shown to be intrinsically brittle, consistent with cleavage facets primarily on this plane in experiments. Twin boundary energies vary considerably but all twin boundary structures possess a mirror reflection symmetry. Finally, in BCC Ti, the $〈111〉/2$ screw has a degenerate core with average glide on $\left\{112\right\}$ planes; the $〈111〉/2$ edge and mixed dislocations have non-dissociated cores on $\left\{110\right\}$ planes. This work paints a self-consistent, complete picture on all dislocations in Ti, rationalises previous experimental observations on Ti plasticity and fracture, and points to future HRTEM examinations of unusual dislocations such as the mixed and PB transformed $〈\mathbf{c}+\mathbf{a}〉$ cores.

Ti 表现出由活性位错和孪晶系统控制的复杂塑性变形。尽管进行了广泛的实验和模拟研究，但目前对位错核和双界面的理解并不完整或定量。在这里，我们使用深电位 (DP)、DFT 和线弹性断裂力学确定 HCP 和 BCC Ti 中的位错核、孪晶和裂纹特性。我们计算核心结构、临界解析剪应力和迁移率$〈\mathbf{A}〉$,$〈\mathbf{C}+\mathbf{A}〉$,$〈\mathbf{C}〉$HCP 中的位错和$〈111〉/\mathrm{2个}$BCC Ti 中的位错。这$〈\mathbf{A}〉$滑移包括锥体 I 平面上的缓慢核心迁移和棱柱平面上的快速迁移，并且在动力学上受到它们之间的交叉滑移的限制。这种行为与 TEM 中的“锁定-解锁”现象一致，很可能是固有属性。大规模 DFT 计算提供了对螺丝的窥视$〈\mathbf{C}+\mathbf{A}〉$核心和滑动行为，使用 DP-Ti 进一步量化。螺丝$〈\mathbf{C}+\mathbf{A}〉$在金字塔 II 平面上不稳定。混合的$〈\mathbf{C}+\mathbf{A}〉$在金字塔-I 平面上几乎无柄，与在该方向上观察到的长位错一致。边缘和混合$〈\mathbf{C}+\mathbf{A}〉$对金字塔到基底（PB）的转变不稳定并且在高温下变得固着，证实了困难$〈\mathbf{C}〉$Ti 的轴压缩。基面上的裂纹被预测并显示出本质上是脆性的，与实验中主要在这个平面上的解理面一致。双边界能量差异很大，但所有双边界结构都具有镜面反射对称性。最后，在 BCC Ti 中，$〈111〉/\mathrm{2个}$螺杆有一个退化的核心，平均滑行$\left\{112\right\}$飞机；这$〈111〉/\mathrm{2个}$边缘位错和混合位错在$\left\{110\right\}$飞机。这项工作描绘了 Ti 中所有位错的自洽、完整的画面，合理化了先前对 Ti 塑性和断裂的实验观察，并指出了未来对不寻常位错的 HRTEM 检查，例如混合和 PB 转换$〈\mathbf{C}+\mathbf{A}〉$核心。