scholarly journals An alternative way to orient the parent phase in the cubic/orthorhombic martensitic transformation of titanium shape memory alloys

2014 ◽  
Vol 83 ◽  
pp. 41-44 ◽  
Author(s):  
Emmanuel Bertrand ◽  
Philippe Castany ◽  
Thierry Gloriant
Keyword(s):  
Martensitic Transformation ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Parent Phase

Self-Accommodating Nature of Martensite Formation in Shape Memory Alloys

2014 ◽  
Vol 213 ◽  
pp. 114-118
Author(s):  
Osman Adiguzel
Keyword(s):  
Martensitic Transformation ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Parent Phase ◽  
Alloy System ◽  
Phase Region ◽  
Martensite Formation ◽  
Martensite Variant ◽  
Β Phase ◽  
Phase Condition

Shape memory effect is a peculiar property exhibited by certain alloy system. This behavior is facilitated by martensitic transformation, and shape memory properties are intimately related to the microstructures of alloys; in particular, the morphology and orientation relationship between the various martensite variants. Martensitic transformation occurs in thermal manner, on cooling the materials from high temperature parent phase region. Thermal induced martensite called self-accommodated martensite or multivariant martensite occurs as multivariant martensite in self-accommodating manner and consists of lattice twins. Shape memory alloys are deformed in low temperature martensitic phase condition, and deformation proceeds through a martensite variant reorientation. Copper based alloys exhibit this property in metastable β - phase region.

Thermal cycling effects in high temperature Cu–Al–Ni–Mn–B shape memory alloys

1997 ◽  
Vol 12 (9) ◽  
pp. 2288-2297 ◽  
Author(s):  
J. Font ◽  
J. Muntasell ◽  
J. Pons ◽  
E. Cesari
Keyword(s):  
High Temperature ◽  
Martensitic Transformation ◽  
Shape Memory Alloys ◽  
Thermal Cycling ◽  
Shape Memory ◽  
Parent Phase ◽  
Aluminum Boride ◽  
Transformation Temperatures ◽  
Dsc Measurements ◽  
Number Of Cycles

The effects of thermal cycling through the martensitic transformation have been studied in three Cu–Al–Ni–Mn–B high temperature shape memory alloys. An increase of the martensitic transformation temperatures with the number of cycles (up to ∼7 K after 60 cycles) has been generally observed by DSC measurements. The microstructure of these alloys is rather complicated, with the presence of big manganese or aluminum boride particles and small boron precipitates, as well as the formation of dislocations during thermal cycling. By means of aging experiments, it has been shown that the evolution of transformation temperatures during cycling is mainly due to the step-by-step aging in parent phase accompanying the thermal cycling, and that the dislocations formed during cycling have only a very small effect, at least up to 60 cycles.

TEM Studies on the Microstructure in Ferromagnetic Shape Memory Alloys

2008 ◽  
Vol 47-50 ◽  
pp. 515-518
Author(s):  
Y. Murakami ◽  
T. Yano ◽  
Daisuke Shindo
Keyword(s):  
Martensitic Transformation ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Parent Phase ◽  
Magnetic Domain ◽  
High Temperature Phase ◽  
Phase Changes ◽  
Temperature Phase ◽  
Ferromagnetic Shape Memory Alloys ◽  
Ferromagnetic Shape Memory

The magnetic domain structures of the cubic parent phase (high-temperature phase) in ferromagnetic shape memory alloys (SMAs) have been studied by electron holography. In a Ni51Fe22Ga17 alloy, the magnetic flux distribution in the parent phase changes dramatically before the onset of martensitic transformation. In contrast, a Ni45Co5Mn36.7In13.3 alloy—a recently developed ferromagnetic SMA—does not show appreciable changes in the magnetic domain structure upon cooling. The anomaly observed in the Ni51Fe22Ga17 alloy appears to be due to lattice distortions, which become more pronounced as the temperature approaches the martensitic transformation start temperature, Ms.

TEM Study of Ni-Mn-Co-In Ferromagnetic Shape Memory Alloys

2012 ◽  
Vol 186 ◽  
pp. 271-274
Author(s):  
Krystian Prusik ◽  
Katarzyna Bałdys ◽  
Danuta Stróż
Keyword(s):  
Martensitic Transformation ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Smart Materials ◽  
Parent Phase ◽  
Cobalt Content ◽  
Indium Content ◽  
Ferromagnetic Shape Memory Alloys ◽  
Transformation Temperatures ◽  
Ferromagnetic Shape Memory

Ferromagnetic shape memory alloys (FSMA) are relatively new smart materials group. Recently, new FSMA from NiMnX (X=Sb, Sn, In, Co+In) systems are considered as alternative to the well known NiMnGa alloys. Four alloys of the following compositions: Ni43Mn35Co4In18, Ni41Mn35Co4In20, Ni42Mn35Co5In18, Ni40Mn35Co5In20 were studied in order to determine microstructure, phase composition and martensitic transformation temperatures versus their chemical composition. Structure of the alloys was studied by optical and transmission electron microscopy (TEM). All of the studied alloys showed macrostructure consisting of radially oriented columnar grains in the direction perpendicular to the casting axis. The structure of the phases occurred in the studied alloys depended on the cobalt and indium content. For the alloys containing 20 at. % of In at room temperature only L21 parent phase was observed whereas for those containing 18 at. % of In either single phase 14M modulated martensite or mixture of 14M martensite and L21 parent phase were seen. DSC measurements showed in studied alloys single-state martensitic transformation. Decrease In content of 2 at.% caused about 80°C fall of martensitic transformation temperatures. Curie temperature Tc increases of 20°C with 1 at% rise of the cobalt content.

Atomic Order and Martensitic Transformation in Cu-Al-Be Shape Memory Alloys

1995 ◽  
Vol 05 (C8) ◽  
pp. C8-973-C8-978
Author(s):  
M. Jurado ◽  
Ll. Mañosa ◽  
A. González-Comas ◽  
C. Stassis ◽  
A. Planes
Keyword(s):  
Martensitic Transformation ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Atomic Order

scholarly journals Effect of Crystallographic Orientation and Grain Boundaries on Martensitic Transformation and Superelastic Response of Oligocrystalline Fe–Mn–Al–Ni Shape Memory Alloys

2021 ◽  
Author(s):  
A. Bauer ◽  
M. Vollmer ◽  
T. Niendorf
Keyword(s):  
Martensitic Transformation ◽  
Grain Boundary ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Grain Boundaries ◽  
Tensile Tests ◽  
Image Correlation ◽  
Stress Concentrations ◽  
Grain Orientations ◽  
High Degree

AbstractIn situ tensile tests employing digital image correlation were conducted to study the martensitic transformation of oligocrystalline Fe–Mn–Al–Ni shape memory alloys in depth. The influence of different grain orientations, i.e., near-〈001〉 and near-〈101〉, as well as the influence of different grain boundary misorientations are in focus of the present work. The results reveal that the reversibility of the martensite strongly depends on the type of martensitic evolving, i.e., twinned or detwinned. Furthermore, it is shown that grain boundaries lead to stress concentrations and, thus, to formation of unfavored martensite variants. Moreover, some martensite plates seem to penetrate the grain boundaries resulting in a high degree of irreversibility in this area. However, after a stable microstructural configuration is established in direct vicinity of the grain boundary, the transformation begins inside the neighboring grains eventually leading to a sequential transformation of all grains involved.

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