Magnetic Shape-Memory (MSM) materials are a new category of actuator materials with the potential to produce both large actuator strain and rapid response. To explore the possibility of developing MSM materials based on Fe-Ni-Co-Ti alloys, the effects of chemical composition (Co/Ni ratio) and ausaging on microstructure and magnetic shapememory response were studied. A suitable choice of chemica...

Article history: Received 29.05.2012. Received in revised form 27.07.2012 Accepted 03.09.2012. The influence of sub-temperature quenching temperature on the tensile strength, hardness and toughness of 60Si2Mn steel has been studied, and the ferrite content, austenite grain size and martensite morphology of the microstructure of this steel after sub-temperature quenching analyzed. The results sh...

Duplex stainless steels (DSSS) have a microstructure composed of ferrite and austenite phases that gives them a very good combination of mechanical and corrosion properties. These steels are desirable for many applications in the chemical and petrochemical industries. In the present study, a type of stainless steel was cast, solution annealed at 1200°C for 60 min and then quenched in water. Ini...

Many studies monitoring the formation of martensite during the tensile deformation of austenite report data which are, in principle, affected by both the applied stress and the resulting plastic strain. It is not clear in these circumstances whether the transformation is stress induced (i.e. the stress provides a mechanical driving force) or whether the generation of defects during deformation ...

We are interested in the phase transformation from austenite to martensite. This transformation is typically accompanied by the generation and growth of small inclusions of martensite. We consider a model from geometrically linear elasticity with sharp energy penalization for phase boundaries. Focusing on a cubic-to-tetragonal phase transformation, we show that the minimal energy for an inclusi...

The Ginzburg-Landau theory for multivariant martensitic phase transformations is advanced in three directions: the potential is developed that introduces the surface tension at interfaces; a mixed term in gradient energy is introduced to control the martensite-martensite interface energy independent of that for austenite-martensite; and a noncontradictory expression for variable surface energy ...

The work reports an experimental observation on crystal rotation in a duplex (austenite + ferrite) steel induced by the electropulsing treatment at ambient temperature, while the temperature rising due to ohmic heating in the treatment was negligible. The results demonstrate that electric current pulses are able to dissolve the initial material's texture that has been formed in prior thermomech...

A shape memory device, and thus the alloy, when not operating is generally held in the martensitic condition. Also the shape memory effect depends on the retransformation of the martensite to the parent phase (i). Use of an alloy in a temperature controlling device, therefore, demands reliability and reproducibility of this retransformation temperature with shape memory cycles and more particul...

The formation of stress-induced martensite in superelastic NiTi was studied by neutron diffraction during uniaxial compressive loading and unloading. The respective phase fractions were determined as a function of the applied stresses using a Rietveld refinement with a March–Dollase texture formulation. Before loading, the specimen was fully austenitic. At the highest applied stress of 2625 MPa...

This paper describes an experimental study of stress-induced martensitic phase transformation in the SMA Nickel-Titanium. The rich local thermo-mechanical interactions that underlie transformation are examined using three-dimensional Digital Image Correlation (strain fields) and infrared imaging (thermal fields). We quantify the complex local interactions between released/absorbed latent heat a...