Smaller is Plastic: Polymorphic Structures and Mechanism of Deformation in Nanoscale hcp Metals.
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.
†Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560 064, India.
Meha
M
Bhogra
‡Department of Materials Engineering, Indian Institute of Science, Bangalore 560 012, India.|§Center of Excellence for Advanced Materials Research, King Abdulaziz University, Jeddah 21589, Saudi Arabia.
U
U
Ramamurty
†Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560 064, India.
Umesh V
UV
Waghmare
Structural transitions; hcp metals; hyperelasticity; planar faults; polymorphism