Superelasticity and shape memory at nano-scale: Size effects on the martensitic transformation

• Published in: Journal of alloys and compounds 2013-11, Vol.577, p.S25-S29
• Main Authors: San Juan, J., Nó, M.L.
• Format: Article
• Language: English
• Subjects: Alloys; Compression tests; Martensitic transformations; Mechanical properties; Metals and alloys; Nanostructure; Origins; Pillars; Shape memory; Stresses; Superelasticity; Transmission electron microscopy
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2011.10.110

► Shape memory alloys exhibit different properties at nano-scale than in bulk materials. ► An overview of the size-effects at nano-scale on the martensitic transformation is presented. ► The size-effects observed on the superelastic behavior at nano-scale are explained in terms of the microscopic mechanisms operating at this small scale. In this work we overview the extrinsic size-effects on the martensitic transformation reported in the literature by nano compression tests in micro and sub-micrometer pillars, as well as by in situ superelastic tests at the transmission electron microscope. Three different size-effects are described: The increase of the critical stress for superelasticity at nano scale, the decrease of the stress for recovery during the reverse stress-induced martensitic transformation at micro and nano scale and finally the change of the selection rule for the martensitic variants promoted at micro and nano scale. New results are presented to illustrate the behavior of these size-effects and the microscopic origin of such effects is discussed. A consistent interpretation is given and explained for each one of the reported size-effects on the martensitic transformation.