Abstract Nanograin materials have superior properties in mechanics, physics and chemistry. Here, we found a new phenomenon that nanograin formation spontaneously occurs in the process of ductile fracture for a titanium alloy, and the dominating mechanism is local severe-plastic-deformation (LSPD). The microstructure evolution during the entire process of monotonic tension was revealed to further understand the ductile fracture from plastic deformation to necking, and to final failure, especially in the post uniform deformation stage, in which the voids nucleate, grow and coalesce. The process of the LSPD can potentially provide a new concept and approach to design and produce high ductile materials, in which nanograin formation will consume massive strain energy to enable the large elongation after specimen necking in the post uniform deformation.

中文翻译：

---

韧性断裂过程中由于局部严重塑性变形在凹坑脊中形成纳米晶粒

摘要 纳米颗粒材料在力学、物理和化学方面具有优越的性能。在这里，我们发现了一种新现象，即钛合金在韧性断裂过程中自发形成纳米晶粒，其主要机制是局部严重塑性变形（LSPD）。揭示了整个单调拉伸过程中的微观结构演变，以进一步了解从塑性变形到颈缩和最终破坏的韧性断裂，特别是在均匀变形后阶段，其中空隙成核、生长和聚结。LSPD 的过程可能为设计和生产高延展性材料提供一种新的概念和方法，其中纳米晶粒的形成将消耗大量应变能，使试样在均匀变形后颈缩后产生较大的伸长率。