Wang Qiannan, Wang Jiangwei, Li Jixue, Zhang Ze, Mao Scott X
Center of Electron Microscopy and State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China.
Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, PA 15261, USA.
Sci Adv. 2018 Jul 6;4(7):eaas8850. doi: 10.1126/sciadv.aas8850. eCollection 2018 Jul.
Plasticity of metallic nanowires is often controlled by the activities of single deformation mode. It remains largely unclear whether multiple deformation modes can be activated in an individual metallic nanowire and how much plasticity they can contribute. In situ nanomechanical testing reveals a superior plastic deformation ability of body-centered cubic (BCC) niobium nanowires, in which a remarkable elongation of more than 269% is achieved before fracture. This superplastic deformation originates from a synergy of consecutively nucleated multiple reorientation processes that occur for more than five times via three distinct mechanisms, that is, stress-activated phase transformation, deformation twinning, and slip-induced crystal rotation. These three coupled mechanisms work concurrently, resulting in sequential reorientations and therefore superplastic deformation of Nb nanowires. Our findings reveal a superior mechanical property of BCC Nb nanowires through the close coordination of multiple deformation modes, which may have some implications in other metallic nanowire systems.
金属纳米线的可塑性通常由单一变形模式的活动控制。目前仍不清楚在单个金属纳米线中是否能激活多种变形模式，以及它们能贡献多少可塑性。原位纳米力学测试揭示了体心立方（BCC）铌纳米线具有卓越的塑性变形能力，其中在断裂前可实现超过269%的显著伸长。这种超塑性变形源于连续成核的多个再取向过程的协同作用，这些过程通过三种不同机制发生超过五次，即应力激活相变、变形孪晶和滑移诱导晶体旋转。这三种耦合机制同时起作用，导致连续的再取向，从而使铌纳米线发生超塑性变形。我们的研究结果通过多种变形模式的紧密协调揭示了BCC铌纳米线卓越的力学性能，这可能对其他金属纳米线系统有一定启示。
