Phase Transformations and Shape Memory Effect in Indium Lead Alloys

In this work we derive a new version of generalized plasticity, suitable to describe phase transformations. In particular, we present a general multi surface formulation of the theory which is capable of describing the multiple and interacting loading mechanisms, which occur during phase transformations. The formulation relies crucially on the consideration of the intrinsic material (“physical”) metric as a primary internal variable and does not invoke any decomposition of the kinematical quantities into elastic and inelastic (transformation induced) parts. The new theory, besides its theoretical interest, is also important for application purposes such as the description and the prediction of the response of shape memory alloy materials. This is shown in the simplest possible setting by the introduction of a material model. The ability of the model in simulating several patterns of the experimentally observed behavior of these materials such as the pseudoelastic phenomenon and the shape memory effect is assessed by representative numerical examples.

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Structure and phase transformations in copper-alloyed rapidly melt-quenched Ni50Ti32Hf18-based alloys with high-temperature shape memory effect

The Physics of Metals and Metallography ◽

10.1134/s0031918x17100118 ◽

2017 ◽

Vol 118 (10) ◽

pp. 997-1005 ◽

Cited By ~ 4

Author(s):

A. V. Pushin ◽

V. G. Pushin ◽

N. N. Kuranova ◽

N. I. Kourov ◽

T. E. Kuntsevich ◽

...

Keyword(s):

High Temperature ◽

Shape Memory ◽

Phase Transformations ◽

Shape Memory Effect ◽

Memory Effect ◽

Structure And Phase Transformations

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Solid State Transformations and Equilibrium Crystal Structures of an Au-Cu Alloy with Shape Memory Effect

Materials Science Forum ◽

10.4028/www.scientific.net/msf.730-732.859 ◽

2012 ◽

Vol 730-732 ◽

pp. 859-864 ◽

Cited By ~ 1

Author(s):

Georgina Miranda ◽

F.S. Silva ◽

Delfim Soares

Keyword(s):

High Temperature ◽

Solid State ◽

Shape Memory ◽

Phase Transformations ◽

Shape Memory Effect ◽

Memory Effect ◽

Equilibrium Phase ◽

Lattice Parameters ◽

Solid State Transformation ◽

Heating And Cooling

Au-50%Cu (at. %) alloy presents the shape memory effect (SME), which is dependent of the solid state transformation that happens during heating, after the introduction of an internal stress in the quenched state. The solid state phase transformation temperatures were determined by means of Differential Thermal Analysis (DTA), both in heating and cooling cycles. With the obtained DTA results, a sequence of high temperature X-ray diffraction (XRD) experiments were made, in order to confirm the presence of the solid state phase transformations and to determine their stable crystal structure and lattice parameters. These XRD results were compared with those obtained from the literature. The displacements of the lattice parameters were determined, for each equilibrium phase, for measurements at room temperature and at high temperature. The characteristics of the quenched samples were also studied in order to determine the phase transformations that are responsible for the shape memory effect in this alloy.

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Phase Transformations, Microstructure and Shape Memory Effect of NiTiAg Alloy with Different Atomic Percentages (at. % Ag) Manufactured by Casting Method

Engineering and Technology Journal ◽

10.30684/etj.v39i4a.1833 ◽

2021 ◽

Vol 39 (4A) ◽

pp. 543-551

Author(s):

Saja M. Hussein ◽

Khansaa D. Salman ◽

Ahmed A. Hussein

Keyword(s):

Shape Memory ◽

Phase Transformations ◽

Shape Memory Effect ◽

Memory Effect ◽

Martensite Phase ◽

Austenite Phase ◽

Vacuum Arc ◽

Casting Method ◽

Vacuum Arc Remelting ◽

Niti Matrix

In this paper, shape memory alloys (SMAs) (NiTi-based) have been manufactured by casting with a different atomic percentage of a silver element (0, 1, 2 and 3 at. % Ag) using a Vacuum Arc Remelting (VAR) furnace. The silver element is added to the binary alloys due to its excellent properties such as (anti-corrosion, anti-bacterial and high electrical conductivity), which make these alloys using in wider applications. These alloys with different atomic percentages (Ni55Ti45Ag0, Ni55Ti44Ag1, Ni55Ti43Ag2 and Ni55Ti42Ag3) have been manufactured. The successful manufacturing process has been achieved and proved via examinations and tests. The FESEM microscopic examinations show that the silver element has been distributed uniformly and homogeneously in the NiTi matrix. Moreover, the emergence of austenite phase, martensite phase and little amount impurities. Regarding the XRD examination, showed that there is an increase in the number of peaks of Ag phase with an increase in the atomic percentage of the silver element, as well to emergence of phase (Ti2Ni) upon heating, phase (Ti 002) upon cooling, and phase (Ni4Ti3) is not desired. The starting and finishing of the phase transformations have been determined for all samples by the DSC test. The Shape Memory Effect (SME) for the alloy (Ni50Ti42Ag3) is measured to be about 89.99%.

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