Surface modifications and their effect on the nickel release rate in nickel–titanium shape memory alloys

2009 ◽  
Vol 100 (8) ◽  
pp. 1099-1108 ◽  
Author(s):  
Christian Heßing ◽  
Michael Pohl
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Release Rate ◽  
Surface Modifications ◽  
Nickel Titanium ◽  
Nickel Release ◽  
Nickel Release Rate

The electron beam freeform fabrication of NiTi shape memory alloys. Part I: Microstructure and physical–chemical behavior

2020 ◽  
pp. 146442072097505
Author(s):  
RPM Guimarães ◽  
F Pixner ◽  
G Trimmel ◽  
J Hobisch ◽  
T Rath ◽  
...  
Keyword(s):  
Electron Beam ◽  
Additive Manufacturing ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Nickel Titanium ◽  
Freeform Fabrication ◽  
Austenitic Transformation ◽  
Columnar Grains ◽  
One Step ◽  
Niti Shape Memory Alloys

Nickel–titanium alloys are the most widely used shape memory alloys due to their outstanding shape memory effect and superelasticity. Additive manufacturing has recently emerged in the fabrication of shape memory alloy but despite substantial advances in powder-based techniques, less attention has been focused on wire-based additive manufacturing. This work reports on the preliminary results for the process-related microstructural and phase transformation changes of Ni-rich nickel–titanium alloy additively manufactured by wire-based electron beam freeform fabrication. To study the feasibility of the process, a simple 10-layer stack structure was successfully built and characterized, exhibiting columnar grains and achieving one-step reversible martensitic–austenitic transformation, thus showing the potential of this additive manufacturing technique for processing shape memory alloys.

scholarly journals Crystallographic Attributes of a Shape-Memory Alloy

1999 ◽  
Vol 121 (1) ◽  
pp. 93-97 ◽  
Author(s):  
Kaushik Bhattacharya
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Nickel Titanium ◽  
Potential Applications

Shape-memory Alloys are attractive for many potential applications. In an attempt to provide ideas and guidelines for the development of new shape-memory alloys, this paper reports on a series of investigations that examine the reasons in the crystallography that make (i) shape-memory alloys special amongst martensites and (ii) Nickel-Titanium special among shape-memory alloys.

Nickel release rate of several nickel-containing stainless steels for jewelries

2015 ◽  
Vol 22 (1) ◽  
pp. 72-77
Author(s):  
Jun-ping Yuan ◽  
Wei Li ◽  
Chang Wang ◽  
Chun-yu Ma ◽  
Ling-xia Chen ◽  
...  
Keyword(s):  
Release Rate ◽  
Stainless Steels ◽  
Nickel Release ◽  
Nickel Release Rate

Coherency strains of H-phase precipitates and their influence on functional properties of nickel-titanium-hafnium shape memory alloys

2018 ◽  
Vol 147 ◽  
pp. 83-87 ◽  
Author(s):  
Behnam Amin-Ahmadi ◽  
Joseph G. Pauza ◽  
Ali Shamimi ◽  
Tom W. Duerig ◽  
Ronald D. Noebe ◽  
...  
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Functional Properties ◽  
Nickel Titanium ◽  
Coherency Strains

Mechanics of nickel–titanium shape memory alloys undergoing partially constrained recovery for self-healing materials

2018 ◽  
Vol 29 (15) ◽  
pp. 3025-3036 ◽  
Author(s):  
Nathan Salowitz ◽  
Ameralys Correa ◽  
Trishika Santebennur ◽  
Afsaneh Dorri Moghadam ◽  
Xiaojun Yan ◽  
...  
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Nickel Titanium ◽  
Self Healing ◽  
Bonding Agents ◽  
Compressive Loads ◽  
Martensitic State ◽  
Geometric Changes ◽  
Shape Memory Fibers

Engineered self-healing materials seek to create an innate ability for materials to restore mechanical strength after incurring damage, much like biological organisms. This technology will enable the design of structures that can withstand their everyday use without damage but also recover from damage due to an overload incident. One of the primary mechanisms for self-healing is the incorporation of shape memory fibers in a composite type structure. Upon activation, these shape memory fibers can restore geometric changes caused by damage and close fractures. To date, shape memory–based self-healing, without bonding agents, has been limited to geometric restoration without creating a capability to withstand externally applied tensile loads due to the way the shape memory material has been integrated into the composite. Some form of bonding has been necessary for self-healing materials to resist an externally applied load after healing. This article presents results of new study into using a form of constrained recovery of nickel–titanium shape memory alloys in self-healing materials to create residual compressive loads across fractures in the low temperature martensitic state. Analysis is presented relating internal loads in self-healing materials, potentially generated by shape memory alloys, to the capability to resist externally applied loads. Supporting properties were experimentally characterized in nickel–titanium shape memory alloy wires. Finally, self-healing samples were synthesized and tested demonstrating the ability to resist externally applies loads without bonding. This study provides a new useful characterization of nickel–titanium applicable to self-healing structures and opens the door to new forms of healing like incorporation of pressure-based bonding.

Creep behavior of Nickel–Titanium shape-memory alloys under static and dynamic loadings: an FEM approach

2021 ◽  
Vol 136 (1) ◽  
Author(s):  
Saad Fariduddin Shaikh ◽  
Subrata Kumar Panda ◽  
Nitin Sharma ◽  
Shreeshan Jena
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Creep Behavior ◽  
Nickel Titanium ◽  
Dynamic Loadings

Quantitative Texture Analysis and Phase Fraction of Nickel-Titanium Shape Memory Alloys by Means of Neutron Diffraction

2004 ◽  
Vol 443-444 ◽  
pp. 267-270 ◽  
Author(s):  
H. Sitepu ◽  
Heinz Günter Brokmeier
Keyword(s):  
Neutron Diffraction ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Orientation Distribution ◽  
Nickel Titanium ◽  
Phase Fraction ◽  
Polycrystalline Nickel ◽  
Minor Variation ◽  
Pole Figures ◽  
Niti Shape Memory Alloys

The orientation distribution function (ODF) of the textured polycrystalline nickel titanium (NiTi) shape memory alloys (SMAs) was determined from the measured austenitic (B2)pole-figures by neutron diffraction. The texture results showed that neutron diffraction is an excellent tool to investigate the minor variation in the texture of NiTi alloys, which is very sensitive to the variation of the content of nickel in the materials. Moreover, the alloys crystallographic phase fraction and texture were calculated from Rietveld refinement with generalized spherical harmonic (GSH) description for the measured complete neutron powder diffraction (ND) spectrum, rather than a few isolated peaks, during in-situ temperature-induced martensitic transformation. The phase fraction results are consistent with the differential scanning calorimeter (DSC) curves.

A novel B19′ martensite in nickel titanium shape memory alloys

2000 ◽  
Vol 48 (6) ◽  
pp. 1325-1344 ◽  
Author(s):  
Madangopal Krishnan ◽  
J.B. Singh
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Nickel Titanium

On the Effect of Latent Heat on the Fracture Toughness of Pseudoelastic Shape Memory Alloys

2014 ◽  
Vol 81 (10) ◽  
Author(s):  
Theocharis Baxevanis ◽  
Chad M. Landis ◽  
Dimitris C. Lagoudas
Keyword(s):  
Fracture Toughness ◽  
Shape Memory Alloys ◽  
Energy Release Rate ◽  
Shape Memory ◽  
Energy Release ◽  
Latent Heat ◽  
Release Rate ◽  
Crack Tip ◽  
Thermomechanical Coupling ◽  
Adiabatic Conditions

A finite element analysis of steady-state crack growth in pseudoelastic shape memory alloys under the assumption of adiabatic conditions is carried out for plane strain, mode I loading. The crack is assumed to propagate at a critical level of the crack-tip energy release rate and the fracture toughness is obtained as the ratio of the far-field applied energy release rate to the crack-tip critical value. Results related to the influence of latent heat on the near-tip stress field and fracture toughness are presented for a range of parameters related to thermomechanical coupling. The levels of fracture toughness enhancement, associated with the energy dissipated by the transformed material in the wake of the growing crack, are found to be lower under adiabatic conditions than under isothermal conditions [Baxevanis et al., 2014, J. Appl. Mech., 81, 041005]. Given that in real applications of shape memory alloy (SMA) components the processes are usually not adiabatic, which is the case with the lowest energy dissipation during a cyclic loading–unloading process (hysteresis), it is expected that the actual level of transformation toughening would be higher than the one corresponding to the adiabatic case.

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