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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Displacive v diffusive phase transformations
Martensitic transformations are very different from those involving diffusion of atoms, i.e. reconstructive transformations. In martensitic transformations, the atoms move in an organised manner relative to their neighbours. This homogeneous shearing of the parent phase creates a new crystal structure, without any compositional change (no diffusion). Martensitic transformations are also known as “diffusionless”, “displacive” or “military”. The difference between displacive and diffusional transformations is demonstrated in the following animation;