The effect of training and predeformation on the martensitic transformation is investigated. It is concluded that Ms as a function of predeformation strain must have a maximum at around 3% strain. Prestrains less than 5% will enhance the martensitic transformation whereas larger prestrains depress it due to strain hardening of the y phase.

Internal friction (IF) was measured in two non-stoichiometric Ni2MnGa alloys. Several IF peaks attributed to some restructuring of the martensitic lattice were observed below Ms. From the strain dependence of IF, the activation enthalpy for movement of twin boundaries between martensitic domains was estimated to be equal to 0.02–0.04 eV. 2003 Acta Materialia Inc. Published by Elsevier Ltd. All ...

We have investigated the effect of pressure and thermal ageing on transformation behavior of Ni-%45.16Ti shape memory alloy. 70-320 MPa pressure was applied and annealed at 500 o C for 2 hour to see the effect of applied pressure on transformation temperature. It was observed that the starting and final temperature of austenit increased, the martensite start temperature almost remain constant a...

The subject of martensitic phase transformation is one of considerable scientific as well as technological interest. Among the martensitic materials, the "shape-memory" alloys have received special attention. ' These alloys exhibit curious elastic behavior near the martensitic transformation temperature (M, ): They can be strained beyond the elastic limit in a reversible manner. In some cases, ...

The basic dynamic behavior of martensitic interfaces has been analyzed within the framework of lattice dislocation dynamics. Two limiting cases of the martensitic interface structure have been considered: (a) the case when the interface can be appropriately described in terms of an array of non-interacting (well-spaced) interfacial dislocations and; (b) the case when the interfacial dislocation...

Low-temperature plastic flow in TRIP steels has been found to be controlled by stress-assisted isothermal martensitic transformation. For these conditions, the thermodynamics and kinetic theory of martensitic transformations leads directly to constitutive relations predicting the dependence of flow stress on temperature, strain, strain-rate, and stress-state, consistent with the observed behavi...

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In this work we report a study of the induced changes in structure and corrosion behavior of martensitic stainless steels nitrided by plasma immersion ion implantation (PI3) at different previous heat treatments. The samples were characterized by x-ray diffraction and glancing angle x-ray diffraction, scanning electron microscopy, energy dispersive x-ray spectroscopy, and potentiodynamic measur...