Development of High-Strength, Fine, and Ultrafine-Grained Shape Memory Alloys

2018 ◽  
Vol 119 (13) ◽  
pp. 1346-1349
Author(s):  
V. G. Pushin ◽  
N. N. Kuranova ◽  
A. V. Pushin
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
High Strength ◽  
Ultrafine Grained

Functional Properties of Ti-Ni-Based Shape Memory Alloys

2008 ◽  
Vol 59 ◽  
pp. 156-161 ◽  
Author(s):  
I. Khmelevskaya ◽  
Sergey Prokoshkin ◽  
Vladimir Brailovski ◽  
K.E. Inaekyan ◽  
Vincent Demers ◽  
...  
Keyword(s):  
Grain Size ◽  
Cold Rolling ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Functional Properties ◽  
High Pressure Torsion ◽  
Martensitic Transformations ◽  
Critical Temperatures ◽  
Recoverable Strain ◽  
Ultrafine Grained

The main functional properties (FP) of Ti-Ni Shape Memory Alloys (SMA) are their critical temperatures of martensitic transformations, their maximum completely recoverable strain (er,1 max) and maximum recovery stress (sr max). Control of the Ti-Ni-based SMA FP develops by forming well-developed dislocation substructures or ultrafine-grained structures using various modes of thermomechanical treatment (TMT), including severe plastic deformation (SPD). The present work shows that TMT, including SPD, under conditions of high pressure torsion (HPT), equal-channel angular pressing (ECAP) or severe cold rolling followed by post-deformation annealing (PDA), which creates nanocrystalline or submicrocrystalline structures, is more beneficial from SMA FP point of view than does traditional TMT creating well-developed dislocation substructure. ECAP and low-temperature TMT by cold rolling followed by PDA allows formation of submicrocrystalline or nanocrystalline structures with grain size from 20 to 300 nm in bulk, and long-size samples of Ti-50.0; 50.6; 50.7%Ni and Ti-47%Ni-3%Fe alloys. The best combination of FP: sr max =1400 MPa and er,1 max=8%, is reached in Ti-Ni SMA after LTMT with e=1.9 followed by annealing at 400°C which results in nanocrystalline (grain size of 50 to 80 nm) structure formation. Application of ultrafine-grained SMA results in decrease in metal consumption for various medical implants and devices based on shape memory and superelastiсity effects.

scholarly journals Structural Change in Ni-Fe-Ga Magnetic Shape Memory Alloys after Severe Plastic Deformation

Materials ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 1939 ◽  
Author(s):  
Gheorghe Gurau ◽  
Carmela Gurau ◽  
Felicia Tolea ◽  
Vedamanickam Sampath
Keyword(s):  
Electron Microscopy ◽  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
High Speed ◽  
High Pressure Torsion ◽  
Magnetic Shape Memory ◽  
Two Phase ◽  
Ultrafine Grained

Severe plastic deformation (SPD) is widely considered to be the most efficient process in obtaining ultrafine-grained bulk materials. The aim of this study is to examine the effects of the SPD process on Ni-Fe-Ga ferromagnetic shape memory alloys (FSMA). High-speed high-pressure torsion (HSHPT) was applied in the as-cast state. The exerted key parameters of deformation are described. Microstructural changes, including morphology that were the result of processing, were investigated by optical and scanning electron microscopy. Energy-dispersive X-ray spectroscopy was used to study the two-phase microstructure of the alloys. The influence of deformation on microstructural features, such as martensitic plates, intragranular γ phase precipitates, and grain boundaries’ dependence of the extent of deformation is disclosed by transmission electron microscopy. Moreover, the work brings to light the influence of deformation on the characteristics of martensitic transformation (MT). Vickers hardness measurements were carried out on disks obtained by SPD so as to correlate the hardness with the microstructure. The method represents a feasible alternative to obtain ultrafine-grained bulk Ni-Fe-Ga alloys.

Shape Memory Alloys for Seismic Response Modification: A State-of-the-Art Review

2005 ◽  
Vol 21 (2) ◽  
pp. 569-601 ◽  
Author(s):  
John C. Wilson ◽  
Michael J. Wesolowsky
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Seismic Response ◽  
Earthquake Engineering ◽  
Materials Science ◽  
State Of The Art ◽  
High Strength ◽  
High Energy ◽  
Hysteretic Behavior ◽  
Seismic Engineering

Shape memory alloys (SMAs) are a remarkable class of metals that can offer high strength, large energy dissipation through hysteretic behavior, extraordinary strain capacity (up to 8%) with full shape recovery to zero residual strain, and a high resistance to corrosion and fatigue—aspects that are all desirable from an earthquake engineering perspective. Their various physical characteristics result from solid-solid transformation between austenite and martensite phases of the alloy that may be induced by stress or temperature. The most commercially successful SMA is a binary alloy of nickel and titanium (NiTi). Although SMAs are expensive relative to most other materials used in seismic engineering, in certain forms their capacity for high energy loss per unit volume means that comparatively small quantities can be made to be especially effective, for example when used in wire form as part of a seismic bracing system. This state-of-the-art paper presents current materials science aspects, material models, and mechanical behavior of SMAs relevant to seismic engineering, and examines the current state of design of SMA-based seismic response modification devices and their use in buildings and bridges. SMA-based devices offer promising advantages for development of next-generation seismic protection systems.

Mechanical Properties of (Pt, Ir)Ti

2005 ◽  
Vol 475-479 ◽  
pp. 1987-1990 ◽  
Author(s):  
Yoko Yamabe-Mitarai ◽  
Toru Hara ◽  
Seiji Miura ◽  
Hideki Hosoda
Keyword(s):  
Phase Transformation ◽  
High Temperature ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
High Strength ◽  
Dislocation Motion ◽  
Phase Transformation Temperature ◽  
High Temperature Strength ◽  
Thermal Expansion Measurement ◽  
Cyclic Compression

We have suggested B2-(Pt, Ir)Ti as high temperature shape memory alloys. The phase transformation of (Pt, Ir)-50at% Ti from B2 to B19(2H) or 4H(4O) structures was investigated in our previous study. The microstructure suggested martensitic transformation. In this study, thermal expansion measurement and cyclic compression test were performed for (Pt, Ir)Ti to investigate if the shape memory effect appears. High temperature strength was also investigated because phase transformation temperature of the (Pt, Ir)Ti is above 1273 K and high strength is necessary as high temperature shape memory alloys in order to suppress dislocation motion and stabilize martenstic transformation. The potential of (Pt, Ir)Ti as high temperature shape memory alloys will be also discussed.

Characterization of high-strength Ti–Ni shape memory alloys prepared by hot pressed sintering

2021 ◽  
Vol 854 ◽  
pp. 157159
Author(s):  
Xiaoyang Yi ◽  
Haizhan Wang ◽  
Kuishan Sun ◽  
Weihong Gao ◽  
Bin Sun ◽  
...  
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
High Strength

Fe-Ni-Al-Ta polycrystalline shape memory alloys showing excellent superelasticity

2019 ◽  
Vol 13 (01) ◽  
pp. 1950096
Author(s):  
Zhaoxia Chen ◽  
Wenyi Peng
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Room Temperature ◽  
High Strength ◽  
Polycrystalline Alloys

Fe-Ni-Co-Al-Ta polycrystalline shape memory alloys have received extensive attention due to their excellent properties such as huge superelasticity, high strength and high damping. We herein report that Fe-Ni-Al-Ta polycrystalline alloys also have excellent superelasticity, which can exhibit a large superelastic strain of more than 17% in compression at room temperature. This superelasticity has slim hysteresis and is greatly affected by the content of Ta in the alloys. In this work, Fe-Ni-Al-Ta shape memory alloys reveal some characteristics that are different from the reported Fe-Ni-Co-Al-based shape memory alloys.

scholarly journals Application of Shape Memory Alloys in Retrofitting of Masonry and Heritage Structures Based on Their Vulnerability Revealed in the Bam 2003 Earthquake

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4480
Author(s):  
Alireza Tabrizikahou ◽  
Marijana Hadzima-Nyarko ◽  
Mieczysław Kuczma ◽  
Silva Lozančić
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
High Strength ◽  
Masonry Structure ◽  
Masonry Buildings ◽  
Masonry Structures ◽  
Structural Failure ◽  
Reinforced Plastics ◽  
Existing Structures ◽  
The City

For decades, one of the most critical considerations of civil engineers has been the construction of structures that can sufficiently resist earthquakes. However, in many parts of the globe, ancient and contemporary buildings were constructed without regard for engineering; thus, there is a rising necessity to adapt existing structures to avoid accidents and preserve historical artefacts. There are various techniques for retrofitting a masonry structure, including foundation isolations, the use of Fibre-Reinforced Plastics (FRPs), shotcrete, etc. One innovative technique is the use of Shape Memory Alloys (SMAs), which improve structures by exhibiting high strength, good re-centring capabilities, self-repair, etc. One recent disastrous earthquake that happened in the city of Bam, Iran, (with a large proportion of masonry buildings) in 2003, with over 45,000 casualties, is analysed to discover the primary causes of the structural failure of buildings and its ancient citadel. It is followed by introducing the basic properties of SMAs and their applications in retrofitting masonry buildings. The outcomes of preceding implementations of SMAs in retrofitting of masonry buildings are then employed to present two comprehensive schemes as well as an implementation algorithm for strengthening masonry structures using SMA-based devices.

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