Metastable β titanium alloys are widely applied in many industries. These alloys can have plastic deformation via dislocation slip, twinning, stress-induced martensite (SIM), or a combination of these. These alloys fail in a ductile manner via a process of void nucleation, growth, and coalescence. Inherent defects, such as voids, are commonly attributed to poor mechanical properties. In this study, aspects of plastic anisotropy in damage accumulation are investigated for metastable crystals that deform by combined slip and SIM. The focus of this study is to understand the evolution of damage due to inherent voids in metastable Ti-10V-2Fe-3Al single crystals. This investigation is conducted using crystal plasticity-based 3D finite element (FE) calculations. A unit-cell FE model involving a spherical void is deformed under constant stress triaxiality and lode parameter. We investigated four triaxiality values at differing lode parameters in three crystal orientations. The void growth was found to be heavily dependent on crystal orientation at low triaxialities. At higher triaxialities, SIM is found to inhibit the void growth via accommodation of the required deformation in the surrounding material. Orientations aligned favourable with SIM undergo significantly less void growth. The accommodation of deformation in the surrounding matrix was found to help preserve the integrity of the void, preventing the localisation of deformation around the void. At lower lode parameter and at higher stress triaxiality this impedes the exponential growth of the void. While, at higher lode parameter with low triaxiality SIM was found to delay the collapse of the void into a crack like morphology. This study not only deepens our understanding of the mechanical behaviour of metastable β titanium alloys, but also unveils the complex interplay between inherent defects, stress-induced martensite, and slip-based plasticity within their crystalline structure, offering fresh perspectives on enhancing material performance.

中文翻译：

---

Ti-10V-2Fe-3Al 亚稳态体心立方晶体中缺陷、马氏体转变和滑移的相互作用：通过晶体塑性有限元方法 (CPFEM) 进行研究


亚稳态β钛合金广泛应用于许多行业。这些合金可以通过位错滑移、孪晶、应力诱导马氏体 (SIM) 或这些的组合产生塑性变形。这些合金通过空洞成核、生长和聚结过程以延展性方式失效。固有缺陷（例如空隙）通常归因于机械性能差。在这项研究中，研究了通过滑移和 SIM 组合变形的亚稳态晶体在损伤累积中的塑性各向异性。本研究的重点是了解亚稳态 Ti-10V-2Fe-3Al 单晶中固有空隙导致的损伤演变过程。这项研究是使用基于晶体塑性的 3D 有限元 (FE) 计算进行的。涉及球形空隙的晶胞有限元模型在恒定应力三轴度和脉线参数下变形。我们研究了三个晶体取向的不同波罗参数下的四个三轴度值。发现空隙生长严重依赖于低三轴度下的晶体取向。在较高的三轴度下，SIM 可通过调节周围材料所需的变形来抑制空隙增长。与 SIM 有利的方向会显着减少空隙的增长。研究发现，周围基质中变形的调节有助于保持空隙的完整性，防止空隙周围变形的局部化。在较低的波线参数和较高的应力三轴度下，这会阻碍空隙的指数增长。同时，在较高的波线参数和较低的三轴度下，SIM 被发现可以延迟空隙塌陷成裂纹状形态。 这项研究不仅加深了我们对亚稳态β钛合金力学行为的理解，而且揭示了其晶体结构中固有缺陷、应力诱导马氏体和滑移塑性之间复杂的相互作用，为增强材料性能提供了新的视角。