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Shape Memory Alloys 2020

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A special issue of Metals (ISSN 2075-4701). This special issue belongs to the section "Corrosion and Protection".

Deadline for manuscript submissions: closed (30 April 2021) | Viewed by 28030

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Prof. Gabriel A. Lopez

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Euskal Herriko Unibertsitatea, Zientzia & Teknol Fak, Fis Aplikatua Saila 2, Bilbao 48080, Spain
Interests: shape memory alloys; advanced metallic materials; electron microscopy; infrared emissivity; alternative energy materials; phase transformations; diffraction

Special Issue Information

Dear Colleagues,

Shape memory alloys (SMAs), in comparison with other materials, have the exceptional ability to change their properties, structures, and functionality depending on the thermal, magnetic, and/or stress fields applied. This ability is based on the very characteristic displacive martensitic transformation from a high-temperature high-symmetry phase to a low-temperature low-symmetry martensite phase that takes place under certain conditions. In this Special Issue of Metals, we are interested in providing an overview of the latest developments of this type of materials, ranging from recent findings from a fundamental point of view, passing through the synthesis and processing methods and going up to the newest discoveries and potential applications in different fields.

As is well-known, in recent decades, the development of SMAs has allowed innovative solutions and alternatives in biomedical applications, advanced engineering structures for aerospace and automotive industries, as well as in sensor and actuation systems, among other sectors. Irrespective of this, designing and engineering using these special smart materials requires a solid background on materials science in order to consolidate their importance in these fields and to broaden their relevance in other new applications. Therefore, contributions on advances in synthesis and processing technologies, as well as new developments in these research fields, both from academic and applied researchers are welcome in this Special Issue.

Prof. Gabriel A. Lopez
Guest Editor

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Keywords

Fundamentals
Advanced synthesis and manufacturing
Simulation and modeling
Advanced characterization
From well-established SMAs to novel SMAs
Biomedical shape memory alloys
High-temperature shape memory alloys
Magnetic shape memory alloys
Applications
Future challenges in the development of SMAs

Published Papers (11 papers)

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Editorial

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2 pages, 189 KiB

Open AccessEditorial

Shape Memory Alloys 2020

by Gabriel A. López

Metals 2021, 11(10), 1618; https://doi.org/10.3390/met11101618 - 12 Oct 2021

Cited by 1 | Viewed by 1630

Abstract

Shape memory alloys (SMAs), in comparison to other materials, have the exceptional ability to change their properties, structures, and functionality, depending on the thermal, magnetic, and/or stress fields applied[...] Full article

(This article belongs to the Special Issue Shape Memory Alloys 2020)

Research

Jump to: Editorial, Review

16 pages, 3438 KiB

Open AccessArticle

Effect of Al Addition on Martensitic Transformation Stability and Microstructural and Mechanical Properties of CuZr Based Shape Memory Alloys

by Carlo Alberto Biffi, Jacopo Fiocchi, Mauro Coduri and Ausonio Tuissi

Metals 2021, 11(7), 1141; https://doi.org/10.3390/met11071141 - 20 Jul 2021

Cited by 1 | Viewed by 1530

Abstract

In this work, the effect of the Al content (x = 5, 10, and 15 at. %) on the martensitic transformation (MT) and microstructure and mechanical properties of Cu_(50−x)Zr₅₀Al_x alloys was studied. The microstructure of the alloys was characterized at room temperature by means of scanning electron microscopy and X-ray diffraction. An increase in Al content reduces the amount of transforming CuZr phase, and consequently the secondary phase formation is favored. The evolution of the MT upon thermal cycling was investigated as a function of the Al content by differential scanning calorimetry. MT temperatures and enthalpies were found to be decreased when increasing the Al content. Al addition can induce a sudden, stable MT below 0 °C, while the binary alloy requires ten complete thermal cycles to stabilize. Finally, the mechanical properties were investigated through microhardness and compression testing. No linear dependence was found with composition. Hardness lowering effect was observed for 5–10 at. % of Al content, while the hardness was increased only for 15 at. % Al addition with respect to the binary alloy. Similarly, compressive response of the alloys showed behavior dependent on the Al content. Up to 10 at. % Al addition, the alloys indicate a superelastic response at room temperature, while higher Al content induced untimely failure. Full article

(This article belongs to the Special Issue Shape Memory Alloys 2020)

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12 pages, 3951 KiB

Open AccessArticle

Martensitic Transformation and Metamagnetic Transition in Co-V-(Si, Al) Heusler Alloys

by Kousuke Nakamura, Atsushi Miyake, Xiao Xu, Toshihiro Omori, Masashi Tokunaga and Ryosuke Kainuma

Metals 2021, 11(2), 226; https://doi.org/10.3390/met11020226 - 28 Jan 2021

Cited by 4 | Viewed by 2411

Abstract

This study investigates the crystal structure, martensitic transformation behavior, magnetic properties, and magnetic-field-induced reverse martensitic transformation of Co₆₄V₁₅(Si_21–xAl_x) alloys. It was found that by increasing the Al composition, the microstructure changes from the martensite phase to the parent phase. The crystal structures of the martensite and parent phases were determined as D0₂₂ and L2₁, respectively. Thermoanalysis and thermomagnetization measurements were used to determine the martensitic transformation and Curie temperatures. Both the ferromagnetic state of the parent phase and that of the martensite phase were observed. With the increasing Al contents, the martensitic transformation temperatures decrease, whereas the Curie temperatures of both the martensite and parent phases increase. The spontaneous magnetization and its composition dependence were also determined. The magnetic-field-induced reverse martensitic transformation of a Co₆₄V₁₅Si₇Al₁₄ alloy under pulsed high magnetic fields was observed. Moreover, using the results of the DSC measurements and the pulsed high magnetization measurements, the temperature dependence of the transformation entropy change of the Co-V-Si-Al alloys was estimated. Full article

(This article belongs to the Special Issue Shape Memory Alloys 2020)

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9 pages, 1819 KiB

Open AccessFeature PaperArticle

Laser Powder Bed Fusion Processing of Fe-Mn-Al-Ni Shape Memory Alloy—On the Effect of Elevated Platform Temperatures

by Felix Clemens Ewald, Florian Brenne, Tobias Gustmann, Malte Vollmer, Philipp Krooß and Thomas Niendorf

Metals 2021, 11(2), 185; https://doi.org/10.3390/met11020185 - 20 Jan 2021

Cited by 14 | Viewed by 2995

Abstract

In order to overcome constraints related to crack formation during additive processing (laser powder bed fusion, L-BPF) of Fe-Mn-Al-Ni, the potential of high-temperature L-PBF processing was investigated in the present study. The effect of the process parameters on crack formation, grain structure, and phase distribution in the as-built condition, as well as in the course of cyclic heat treatment was examined by microstructural analysis. Optimized processing parameters were applied to fabricate cylindrical samples featuring a crack-free and columnar grained microstructure. In the course of cyclic heat treatment, abnormal grain growth (AGG) sets in, eventually promoting the evolution of a bamboo like microstructure. Testing under tensile load revealed a well-defined stress plateau and reversible strains of up to 4%. Full article

(This article belongs to the Special Issue Shape Memory Alloys 2020)

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15 pages, 8008 KiB

Open AccessArticle

Control of Density and Grain Structure of a Laser Powder Bed-Fused Superelastic Ti-18Zr-14Nb Alloy: Simulation-Driven Process Mapping

by Vladimir Brailovski, Victoria Kalinicheva, Morgan Letenneur, Konstantin Lukashevich, Vadim Sheremetyev and Sergey Prokoshkin

Metals 2020, 10(12), 1697; https://doi.org/10.3390/met10121697 - 21 Dec 2020

Cited by 11 | Viewed by 2895

Abstract

This study focuses on the control of density and grain structure of a superelastic Ti-18Zr-14Nb (at. %) alloy subjected to laser powder bed fusion. It starts with the production and characterization of a Ti-18Zr-14Nb powder feedstock and printing of a series of calibration specimens. These specimens are next subjected to chemical, structural, phase and texture analyses in order to collect experimental data needed to build simulation-driven processing maps in the laser energy density–material build rate coordinates. The results of this study prove that, once calibrated, the simulation-driven processing maps can be used to relate the main LPBF parameters (laser power, scanning speed, hatching distance and layer thickness) to the density and grain structure of the printed material, and the process productivity (build rate). Even though this demonstration is made for a specific material–system combination (TiNbZr & TruPrint 1000), such a process mapping is feasible for any material–system combination and can, therefore, be exploited for the process optimization purposes and for manufacturing of functionally graded materials or parts with intentionally seeded porosity. Full article

(This article belongs to the Special Issue Shape Memory Alloys 2020)

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13 pages, 641 KiB

Open AccessArticle

Softening of Shear Elastic Coefficients in Shape Memory Alloys Near the Martensitic Transition: A Study by Laser-Based Resonant Ultrasound Spectroscopy

by Petr Sedlák, Michaela Janovská, Lucie Bodnárová, Oleg Heczko and Hanuš Seiner

Metals 2020, 10(10), 1383; https://doi.org/10.3390/met10101383 - 16 Oct 2020

Cited by 9 | Viewed by 2055

Abstract

We discuss the suitability of laser-based resonant ultrasound spectroscopy (RUS) for the characterization of soft shearing modes in single crystals of shape memory alloys that are close to the transition temperatures. We show, using a numerical simulation, that the RUS method enables the [...] Read more.

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shear elastic coefficient, even for very strong anisotropy, and without being sensitive to misorientations of the used single crystal. Subsequently, we apply the RUS method to single crystals of three typical examples of shape memory alloys (Cu-Al-Ni, Ni-Mn-Ga, and NiTi), and discuss the advantages of using the laser-based contactless RUS arrangement for temperature-resolved measurements of elastic constants. Full article

(This article belongs to the Special Issue Shape Memory Alloys 2020)

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12 pages, 1576 KiB

Open AccessArticle

Influence of Structural Defects on the Properties of Metamagnetic Shape Memory Alloys

by J. I. Pérez-Landazábal, V. Sánchez-Alarcos, V. Recarte, O. A. Lambri, F. G. Bonifacich, D. L.R. Khanna, I. Unzueta, J.A. García, F. Plazaola, J. López-García, M. Jimenez Ruiz, J.A. Rodríguez-Velamazán and E. Cesari

Metals 2020, 10(9), 1131; https://doi.org/10.3390/met10091131 - 22 Aug 2020

Cited by 6 | Viewed by 2197

Abstract

The production of μ-particles of Metamagnetic Shape Memory Alloys by crushing and subsequent ball milling process has been analyzed. The high energy involved in the milling process induces large internal stresses and high density of defects with a strong influence on the martensitic transformation; the interphase creation and its movement during the martensitic transformation produces frictional contributions to the entropy change (exothermic process) both during forward and reverse transformation. The frictional contribution increases with the milling time as a consequence of the interaction between defects and interphases. The influence of the frictional terms on the magnetocaloric effect has been evidenced. Besides, the presence of antiphase boundaries linked to superdislocations helps to understand the spin-glass behavior at low temperatures in martensite. Finally, the particles in the deformed state were introduced in a photosensitive polymer. The mechanical damping associated to the Martensitic Transformation (MT) of the particles is clearly distinguished in the produced composite, which could be interesting for the development of magnetically-tunable mechanical dampers. Full article

(This article belongs to the Special Issue Shape Memory Alloys 2020)

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9 pages, 5105 KiB

Open AccessArticle

Microstructural and Mechanical Response of NiTi Lattice 3D Structure Produced by Selective Laser Melting

by Carlo Alberto Biffi, Paola Bassani, Jacopo Fiocchi and Ausonio Tuissi

Metals 2020, 10(6), 814; https://doi.org/10.3390/met10060814 - 18 Jun 2020

Cited by 28 | Viewed by 3143

Abstract

Nowadays, additive manufacturing (AM) permits to realize complex metallic structural parts, and the use of NiTi alloy, known as Nitinol, allows the integration of specific functions to the AM products. One of the most promising designs for AM is concerning the use of lattice structures that show lightweight, higher than bulk material deformability, improved damping properties, high exchange surface. Moreover, lattice structures can be realized with struts, having dimensions below 1 mm—this is very attractive for the realization of Nitinol components for biomedical devices. In this light, the present work regarded the experimental characterization of lattice structures, produced by selective laser melting (SLM), by using Ni-rich NiTi alloy. Differential scanning calorimetry (DSC), electron backscatter diffraction (EBSD), and compression testing were carried out for analyzing microstructure, martensitic transformation (MT) evolution, and superelasticity response of the SLMed lattice samples. The lattice microstructures were compared with those of the SLMed bulk material for highlighting differences. Localized martensite was detected in the nodes zones, where the rapid solidification tends to accumulate solidification stresses. An increase of martensitic transformation temperatures was also observed in lattice NiTi. Full article

(This article belongs to the Special Issue Shape Memory Alloys 2020)

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11 pages, 4473 KiB

Open AccessArticle

{111}<110> Orientation Induced Anisotropy of Shape Memory Effect in NiTiNb Pipe Joints

by Mingyan Sun, Qichao Fan, Yingying Wang, Qin Yang, Jie Chen, Shuke Huang and Yonghao Zhang

Metals 2020, 10(6), 776; https://doi.org/10.3390/met10060776 - 11 Jun 2020

Cited by 4 | Viewed by 2059

Abstract

This work aims to clarify the influence of texture type and intensity on the shape memory effect (SME) in NiTiNb shape memory alloy (SMA) pipe joints, especially revealing the causes for the anisotropy of SME via texture changes. Three NiTiNb rods with different intensities of the {111}<110> texture were fabricated, and their microstructures, crystalline orientation distribution functions and inverse pole figures were obtained by X-ray diffraction and electron backscatter diffraction measurements. Simultaneously, the SME was characterized by inner-diameter recoverability of the corresponding pipe joints. For a given intensity of the {111}<110> texture, the SME of the NiTiNb pipe joints strongly depended on the expansion direction due to {111}<110> orientation-induced anisotropy of SME. In addition, both the SME and anisotropy of NiTiNb pipe joints increased with the increased intensity of the {111}<110> texture. Therefore, a suitable expansion direction and strong texture intensity should be considered for high SME in NiTiNb pipe joints. Full article

(This article belongs to the Special Issue Shape Memory Alloys 2020)

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17 pages, 15698 KiB

Open AccessArticle

Hysteretic Behavior and Ultimate Energy Dissipation Capacity of Large Diameter Bars Made of Shape Memory Alloys under Seismic Loadings

by Guillermo González-Sanz, David Galé-Lamuela, David Escolano-Margarit and Amadeo Benavent-Climent

Metals 2019, 9(10), 1099; https://doi.org/10.3390/met9101099 - 13 Oct 2019

Cited by 5 | Viewed by 3547

Abstract

Shape memory alloys in the form of bars are increasingly used to control structures under seismic loadings. This study investigates the hysteretic behavior and the ultimate energy dissipation capacity of large-diameter NiTi bars subjected to low- and high-cycle fatigue. Several specimens are subjected to quasi-static and to dynamic cyclic loading at different frequencies. The influence of the rate of loading on the shape of the hysteresis loops is analysed in terms of the amount of dissipated energy, equivalent viscous damping, variations of the loading/unloading stresses, and residual deformations. It is found that the log-log scale shows a linear relationship between the number of cycles to failure and the normalized amount of energy dissipated in one cycle, both for low- and for high-cycle fatigue. Based on the experimental results, a numerical model is proposed that consists of two springs with different restoring force characteristics (flag-shape and elastic-perfectly plastic) connected in series. The model can be used to characterize the hysteretic behavior of NiTi bars used as energy dissipation devices in advanced earthquake resistant structures. The model is validated with shake table tests conducted on a reinforced concrete structure equipped with 12.7 mm diameter NiTi bars as energy dissipation devices. Full article

(This article belongs to the Special Issue Shape Memory Alloys 2020)

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Review

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21 pages, 2757 KiB

Open AccessReview

TiPd- and TiPt-Based High-Temperature Shape Memory Alloys: A Review on Recent Advances

by Yoko Yamabe-Mitarai

Metals 2020, 10(11), 1531; https://doi.org/10.3390/met10111531 - 18 Nov 2020

Cited by 23 | Viewed by 2904

Abstract

In this paper high-temperature shape memory alloys based on TiPd and TiPt are reviewed. The effect of the alloying elements in ternary TiPd and TiPt alloys on phase transformation and strain recovery is also discussed. Generally, the addition of alloying elements decreases the martensitic transformation temperature and improves the strength of the martensite and austenite phases. Additionally, it also decreases irrecoverable strain, but without perfect recovery due to plastic deformation. With the aim to improve the strength of high-temperature shape memory alloys, multi-component alloys, including medium- and high-entropy alloys, have been investigated and proposed as new structural materials. Notably, it was discovered that the martensitic transformation temperature could be controlled through a combination of the constituent elements and alloys with high austenite finish temperatures above 500 °C. The irrecoverable strain decreased in the multi-component alloys compared with the ternary alloys. The repeated thermal cyclic test was effective toward obtaining perfect strain recoveries in multi-component alloys, which could be good candidates for high-temperature shape memory alloys. Full article

(This article belongs to the Special Issue Shape Memory Alloys 2020)

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