Pseudoelasticity, sometimes called superelasticity, is an elastic (reversible) response to an applied stress, caused by a phase transformation between the austenitic and martensitic phases of a crystal. It is exhibited in shape-memory alloys.
Pseudoelasticity is from the reversible motion of domain boundaries during the phase transformation, rather than just bond stretching or the introduction of defects in the crystal lattice (thus it is not true superelasticity but rather pseudoelasticity). Even if the domain boundaries do become pinned, they may be reversed through heating. Thus, a pseudoelastic material may return to its previous shape (hence, shape memory) after the removal of even relatively high applied strains. One special case of pseudoelasticity is called the Bain Correspondence. This involves the austenite/martensite phase transformation between a face-centered crystal lattice (FCC) and a body-centered tetragonal crystal structure (BCT).[1]
Superelastic alloys belong to the larger family of shape-memory alloys. When mechanically loaded, a superelastic alloy deforms reversibly to very high strains (up to 10%) by the creation of a stress-induced phase. When the load is removed, the new phase becomes unstable and the material regains its original shape. Unlike shape-memory alloys, no change in temperature is needed for the alloy to recover its initial shape.
Superelastic devices take advantage of their large, reversible deformation and include antennas, eyeglass frames, and biomedical stents.
Nickel titanium (Nitinol) is an example of an alloy exhibiting superelasticity.
Size effectsedit
Recently, there have been interests of discovering materials exhibiting superelasticity in nanoscale for MEMS (Microelectromechanical systems) application. The ability to control the martensitic phase transformation has already been reported.[2] But the behavior of superelasticity has been observed to have size effects in nanoscale.
Qualitatively speaking, superelasticity is the reversible deformation by phase transformation. Therefore, it competes with the irreversible plastic deformation by dislocation motion. At nanoscale, the dislocation density and possible Frank–Read source sites are greatly reduced, so the yield stress is increased with reduced size. Therefore, for materials exhibiting superelasticity behavior in nanoscale, it has been found that they can operate in long-term cycling with little detrimental evolution.[3] On the other hand, the critical stress for martensitic phase transformation to occur is also increased because of the reduced possible sites for nucleation to begin. Nucleation usually begins near dislocation or at surface defects. But for nanoscale materials, the dislocation density is greatly reduced, and the surface is usually atomically smooth. Therefore, the phase transformation of nanoscale materials exhibiting superelasticity is usually found to be homogeneous, resulting in much higher critical stress.[4] Specifically, for Zirconia, where it has three phases, the competition between phase transformation and plastic deformation has been found to be orientation dependent,[5] indicating the orientation dependence of activation energy of dislocation and nucleation. Therefore, for nanoscale materials suitable for superelasticity, one should research on the optimized crystal orientation and surface roughness for most enhanced superelasticity effect.
^Bhadeshia, H. K. D. H. "The Bain Correspondence" (PDF). Materials Science and Metallurgy. University of Cambridge.
^Thorsten Krenke; et al. (2007). "Magnetic superelasticity and inverse magnetocaloric effect in Ni-Mn-In". Physical Review B. 75 (10): 104414. arXiv:0704.1243. Bibcode:2007PhRvB..75j4414K. doi:10.1103/PhysRevB.75.104414. S2CID 29563170.
^J. San Juan; et al. (2014). "Long-term superelastic cycling at nano-scale in Cu-Al-Ni shape memory alloy micropillars". Applied Physics Letters. 104 (1). AIP: 011901. Bibcode:2014ApPhL.104a1901S. doi:10.1063/1.4860951.
^J. San Juan; et al. (2013). "superelasticity and shape memory at nano-scale: size effects on the martensitic transformation". Journal of Alloys and Compounds. 577. Elsevier: S25–S29. doi:10.1016/j.jallcom.2011.10.110.
^Ning Zhang; et al. (2016). "Competing mechanisms between dislocation and phase transformation in plastic deformation of single crystalline yttria-stabilized tetragonal zirconia nanopillars". Acta Materialia. 120: 337–347. arXiv:1607.03141. Bibcode:2016AcMat.120..337Z. doi:10.1016/j.actamat.2016.08.075. S2CID 118512427.
Liang C., Rogers C. A. (1990). "One-Dimensional Thermomechanical Constitutive Relations for Shape Memory Materials". Journal of Intelligent Material Systems and Structures. 1 (2): 207–234. doi:10.1177/1045389x9000100205. S2CID 135569418.
Miyazaki S, Otsuka K, Suzuki Y (1981). "Transformation Pseudoelasticity and Deformation Behavior in a Ti-50.6at%Ni Alloy". Scripta Metallurgica. 15 (3): 287–292. doi:10.1016/0036-9748(81)90346-x.
Huo, Y.; Müller, I. (1993). "Nonequilibrium thermodynamics of pseudoelasticity". Continuum Mechanics and Thermodynamics. 5 (3). Springer Science and Business Media LLC: 163–204. Bibcode:1993CMT.....5..163H. doi:10.1007/bf01126524. ISSN 0935-1175. S2CID 123040312.
Tanaka K., Kobayashi S., Sato Y. (1986). "Thermomechanics of transformation pseudoelasticity and shape memory effect in alloys". International Journal of Plasticity. 2 (1): 59–72. doi:10.1016/0749-6419(86)90016-1.{{cite journal}}: CS1 maint: multiple names: authors list (link)
Kamita, Toru; Matsuzaki, Yuji (1998-08-01). "One-dimensional pseudoelastic theory of shape memory alloys". Smart Materials and Structures. 7 (4). IOP Publishing: 489–495. Bibcode:1998SMaS....7..489K. doi:10.1088/0964-1726/7/4/008. ISSN 0964-1726. S2CID 250834042.
Yamada, Y. (1992-09-01). "Theory of pseudoelasticity and the shape-memory effect". Physical Review B. 46 (10). American Physical Society (APS): 5906–5911. Bibcode:1992PhRvB..46.5906Y. doi:10.1103/physrevb.46.5906. ISSN 0163-1829. PMID 10002272.
External linksedit
DoITPoMS Teaching and Learning Package: "Superelasticity and Shape Memory Alloys"
April 12, 2024
pseudoelasticity, sometimes, called, superelasticity, elastic, reversible, response, applied, stress, caused, phase, transformation, between, austenitic, martensitic, phases, crystal, exhibited, shape, memory, alloys, contents, overview, size, effects, also, r. Pseudoelasticity sometimes called superelasticity is an elastic reversible response to an applied stress caused by a phase transformation between the austenitic and martensitic phases of a crystal It is exhibited in shape memory alloys Contents 1 Overview 2 Size effects 3 See also 4 References 5 External linksOverview editPseudoelasticity is from the reversible motion of domain boundaries during the phase transformation rather than just bond stretching or the introduction of defects in the crystal lattice thus it is not true superelasticity but rather pseudoelasticity Even if the domain boundaries do become pinned they may be reversed through heating Thus a pseudoelastic material may return to its previous shape hence shape memory after the removal of even relatively high applied strains One special case of pseudoelasticity is called the Bain Correspondence This involves the austenite martensite phase transformation between a face centered crystal lattice FCC and a body centered tetragonal crystal structure BCT 1 Superelastic alloys belong to the larger family of shape memory alloys When mechanically loaded a superelastic alloy deforms reversibly to very high strains up to 10 by the creation of a stress induced phase When the load is removed the new phase becomes unstable and the material regains its original shape Unlike shape memory alloys no change in temperature is needed for the alloy to recover its initial shape Superelastic devices take advantage of their large reversible deformation and include antennas eyeglass frames and biomedical stents Nickel titanium Nitinol is an example of an alloy exhibiting superelasticity Size effects editRecently there have been interests of discovering materials exhibiting superelasticity in nanoscale for MEMS Microelectromechanical systems application The ability to control the martensitic phase transformation has already been reported 2 But the behavior of superelasticity has been observed to have size effects in nanoscale Qualitatively speaking superelasticity is the reversible deformation by phase transformation Therefore it competes with the irreversible plastic deformation by dislocation motion At nanoscale the dislocation density and possible Frank Read source sites are greatly reduced so the yield stress is increased with reduced size Therefore for materials exhibiting superelasticity behavior in nanoscale it has been found that they can operate in long term cycling with little detrimental evolution 3 On the other hand the critical stress for martensitic phase transformation to occur is also increased because of the reduced possible sites for nucleation to begin Nucleation usually begins near dislocation or at surface defects But for nanoscale materials the dislocation density is greatly reduced and the surface is usually atomically smooth Therefore the phase transformation of nanoscale materials exhibiting superelasticity is usually found to be homogeneous resulting in much higher critical stress 4 Specifically for Zirconia where it has three phases the competition between phase transformation and plastic deformation has been found to be orientation dependent 5 indicating the orientation dependence of activation energy of dislocation and nucleation Therefore for nanoscale materials suitable for superelasticity one should research on the optimized crystal orientation and surface roughness for most enhanced superelasticity effect See also editShape memory alloy Elasticity physics References edit Bhadeshia H K D H The Bain Correspondence PDF Materials Science and Metallurgy University of Cambridge Thorsten Krenke et al 2007 Magnetic superelasticity and inverse magnetocaloric effect in Ni Mn In Physical Review B 75 10 104414 arXiv 0704 1243 Bibcode 2007PhRvB 75j4414K doi 10 1103 PhysRevB 75 104414 S2CID 29563170 J San Juan et al 2014 Long term superelastic cycling at nano scale in Cu Al Ni shape memory alloy micropillars Applied Physics Letters 104 1 AIP 011901 Bibcode 2014ApPhL 104a1901S doi 10 1063 1 4860951 J San Juan et al 2013 superelasticity and shape memory at nano scale size effects on the martensitic transformation Journal of Alloys and Compounds 577 Elsevier S25 S29 doi 10 1016 j jallcom 2011 10 110 Ning Zhang et al 2016 Competing mechanisms between dislocation and phase transformation in plastic deformation of single crystalline yttria stabilized tetragonal zirconia nanopillars Acta Materialia 120 337 347 arXiv 1607 03141 Bibcode 2016AcMat 120 337Z doi 10 1016 j actamat 2016 08 075 S2CID 118512427 Liang C Rogers C A 1990 One Dimensional Thermomechanical Constitutive Relations for Shape Memory Materials Journal of Intelligent Material Systems and Structures 1 2 207 234 doi 10 1177 1045389x9000100205 S2CID 135569418 Miyazaki S Otsuka K Suzuki Y 1981 Transformation Pseudoelasticity and Deformation Behavior in a Ti 50 6at Ni Alloy Scripta Metallurgica 15 3 287 292 doi 10 1016 0036 9748 81 90346 x Huo Y Muller I 1993 Nonequilibrium thermodynamics of pseudoelasticity Continuum Mechanics and Thermodynamics 5 3 Springer Science and Business Media LLC 163 204 Bibcode 1993CMT 5 163H doi 10 1007 bf01126524 ISSN 0935 1175 S2CID 123040312 Tanaka K Kobayashi S Sato Y 1986 Thermomechanics of transformation pseudoelasticity and shape memory effect in alloys International Journal of Plasticity 2 1 59 72 doi 10 1016 0749 6419 86 90016 1 a href Template Cite journal html title Template Cite journal cite journal a CS1 maint multiple names authors list link Kamita Toru Matsuzaki Yuji 1998 08 01 One dimensional pseudoelastic theory of shape memory alloys Smart Materials and Structures 7 4 IOP Publishing 489 495 Bibcode 1998SMaS 7 489K doi 10 1088 0964 1726 7 4 008 ISSN 0964 1726 S2CID 250834042 Yamada Y 1992 09 01 Theory of pseudoelasticity and the shape memory effect Physical Review B 46 10 American Physical Society APS 5906 5911 Bibcode 1992PhRvB 46 5906Y doi 10 1103 physrevb 46 5906 ISSN 0163 1829 PMID 10002272 External links editDoITPoMS Teaching and Learning Package Superelasticity and Shape Memory Alloys Retrieved from https en wikipedia org w index php title Pseudoelasticity amp oldid 1122169276, wikipedia, wiki, book, books, library,
