Specific heat was systematically measured by the heat flow method in Ni50−xCoxMn50−yAly metamagnetic shape memory alloys near the martensitic transformation temperatures. Martensitic transformation and ferromagnetic–paramagnetic transition for the parent phase were directly observed via the specific heat measurements. On the basis of the experimental results, the entropy change was estimated an...

We report on the magnetic and martensitic transformation properties of Co39Ni33Al28 ferromagnetic shape memory alloy ribbons. We found that the phase formation of Co39Ni33Al28 is strongly dependent on the method of preparation. The conventional as-cast ingot sample contains a large amount of the γ phase embedded in the primary β phase, while melt-spun ribbons contain the pure β phase. Co39Ni33A...

We describe a general theory for the stability of the laminated mi-crostructure for martensitic crystals. Our theory has been applied to the orthorhom-bic to monoclinic transformation, the cubic to tetragonal transformation, the tetrag-onal to monoclinic transformation, and the cubic to orthorhombic transformation.

In this chapter the theoretical basics important to understand all aspects of this work are presented. Theoretical concepts that are import for single chapters only are presented accordingly. In the first section, fundamental properties of the martensitic transformation are introduced. The concept of phase compatibility is introduced in the following section. In the last section, the influences...

We report stress-induced martensitic transformation in tensile loaded Fe–30.5 at.% Pd polycrystals, mainly using optical microscopy. Reverse transformation occurs during unloading. Thermodynamic relationships between applied stress, transformation strain and the latent heat of transformation are examined. 2002 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.

A finite element approximation of the thin film limit for a sharp interface bulk energy for martensitic crystals is given. The energy density models the softening of the elastic modulus controlling the low-energy path from the cubic to the tetragonal lattice, the loss of stability of the tetragonal phase at high temperatures and the loss of stability of the cubic phase at low temperatures, and ...

S. H. Chang, S. H. Hsiao, National I-Lan University, Taiwan Cold-rolled and annealed Ti50Ni40Cu10 shape memory alloy possesses a major (110)[001] texture along the rolling direction and a minor {111} γ-fiber texture along the normal direction. The damping capacity of the B2→B19 and B19→B2 martensitic transformation internal friction peaks for the Ti50Ni40Cu10 shape memory alloy was more pr...

Effects of ultra high magnetic field of both pulse and steady types on martensitic transformation have been studied, using Fe-Ni-Mn, Fe-Ni-Mn-C alloys with the supplemental tests on Fe-Ni-C and Fe-NiCo-Ti alloys. It is found that the martensitic transformation is induced at room temperature not only athermally but also isothermally either by pulse magnetic field or by steady magnetic field for ...

A new process and mechanism are presented for controlling the shape memory response spatially within monolithic NiTi thin film structures. This technique is shown to effectively control the martensitic phase transformation temperature and exhibits control over aspects of the mechanical and shape memory responses as well. Specifically, the martensitic phase transformation temperature decreases w...