Smaller is Plastic: Polymorphic Structures and Mechanism of Deformation in Nanoscale hcp Metals

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• 作者：Meha Bhogra ; U. Ramamurty ; Umesh V. Waghmare
• 刊名：Nano Letters
• 出版年：2015
• 出版时间：June 10, 2015
• 年：2015
• 卷：15
• 期：6
• 页码：3697-3702
• 全文大小：373K
• ISSN：1530-6992

文摘

Using first-principles calculations, we establish the existence of highly stable polymorphs of hcp metals (Ti, Mg, Be, La and Y) with nanoscale structural periodicity. They arise from heterogeneous deformation of the hcp structure occurring in response to large shear stresses localized at the basal planes separated by a few nanometers. Through Landau theoretical analysis, we show that their stability derives from nonlinear coupling between strains at different length scales. Such multiscale hyperelasticity and long-period structures constitute a new mechanism of size-dependent plasticity and its enhancement in nanoscale hcp metals.