Superelasticity and Shape Memory Alloys
AimsBefore you startIntroductionMartensitic Phase Transformations - A Simple ExampleMartensitic Phase Transformations - Basic ThermodynamicsMartensitic Phase Transformations - Hysteresis CharacteristicsSuperelasticity - Strain Accommodation by Martensite FormationSuperelasticity - Hysteresis in the Stress-Strain BehaviourShape Memory Effect - "Training" of the TransformationShape Memory Effect - The "Ferris Wheel" ExperimentMicrostructural Changes during Thermo-Mechanical TreatmentLimits of SuperelasticityApplicationsSummaryQuestionsGoing furtherTLP creditsTLP contentsShow all contentViewing and downloading resourcesAbout the TLPsTerms of useFeedbackCredits Print this page
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Deformation Twinning
Since in twinning only a small movement of atoms occurs and it is a co-operative process it can occur much more quickly than slip, making it much more common in high stress rate situations; for example, they are often seen when a material has exploded. Also they are preferentially formed when there are few slip systems available, which is the case in low symmetry crystals. This is why they occur readily in shape memory alloys which are usually hcp or monoclinic.