Shape memory at nanometer scales

Nickel-titanium (NiTi) shape memory alloys undergo relatively large recoverable inelastic deformations via a stress-induced martensitic phase transformation. The nanoindentation experimental results presented in this study are the first to show evidence of discrete forward and reverse stress-induced thermoelastic martensitic transformations in nanometer scaled volumes of material. Shape recovery due to indentation, followed by subsequent heating, is demonstrated for indents depths in the sub 10 nm range via atomic force microscopy. It is also shown that the local material structure can be utilized to modify transformation behavior at nanometer scales, yielding insight into the nature of stress-induced martensitic phase transformations at small scales and providing opportunity for the design of nanometer sized NiTi actuators. © 2006 Materials Research Society.

Duke Scholars

Author Ken Gall Thomas Lord Department of Mechanical Engineering and Materia ...