Enhanced shape memory and superelasticity in small-volume ceramics: a perspective on the controlling factors
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Prospective Article
Enhanced shape memory and superelasticity in small-volume ceramics: a perspective on the controlling factors Xiaomei Zeng, Temasek Laboratories, Nanyang Technological University, 637553, Singapore; Temasek Laboratories, Nanyang Technological University, 637553, Singapore Zehui Du, Temasek Laboratories, Nanyang Technological University, 637553, Singapore Christopher A. Schuh, Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA 02139, USA Chee Lip Gan, Temasek Laboratories, Nanyang Technological University, 637553, Singapore Address all correspondence to Chee Lip Gan at [email protected] (Received 13 July 2017; accepted 8 September 2017)
Abstract Shape memory ceramics show potential for energy damping and actuation applications. In particular, small-scale structures of zirconia-based ceramics demonstrate significantly enhanced shape memory and superelastic properties compared with their bulk counterparts, mainly because an oligocrystalline or single-crystal microscale structure reduces mismatch stresses amongst grains. In this Prospective article, we review recent experiments that explore the shape memory properties of small-scale zirconia-based ceramics, including the effects of composition, sample and grain size, and cyclic loading. These factors are reviewed with an eye toward rendering shape memory ceramics more useful in future applications.
Introduction Zirconia-based ceramics can experience a martensitic transformation between tetragonal and monoclinic phases under the stimulus of heat or external stress.[1] This transformation occurs rapidly in a crystallographic and reversible manner, and has been extensively studied in large part due to its beneficial effects as a toughening mechanism.[2,3] More interestingly, the large reversible shear strain (∼16%) associated with the martensitic transformation makes zirconia-based ceramics promising candidates as shape memory materials.[4,5] Swain[6] first reported signatures of shape memory behavior in partially stabilized zirconia during thermal treatment in 1986. Reyes-Morel et al.[7] further demonstrated the shape memory effect (SME) and superelasticity (SE) in zirconia ceramics with macroscopic shape deformation and recovery under uniaxial compression in 1988. However, due to their polycrystalline nature, zirconia-based ceramics in bulk form suffer from microcracks along grain boundaries and other permanent structural damage during shape deformation, leading to limited macroscopic strain (
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