High-temperature martensitic transformation of CuNiHfTiZr high- entropy alloys

AbstractOne of the major challenges of near-equiatomic NiTi shape memory alloys is their limitation for high-temperature applications. To overcome this barrier, researchers have tried to enhance the transformation temperatures by addition of alloying elements or even by introducing the concept of high-entropy alloys (HEAs). In this study, the CuNiHfTiZr HEAs were developed for high-temperature shape memory effect. Based on their solubility and electron configurations, the alloying elements are divided into two groups, (CuNi)50 and (HfTiZr)50. The content of Cu in (CuNi)50 is modulated to investigate the influences of Cu on martensitic transformation of the HEAs by studying structural evolution and transformation behavior. The results of x-ray diffraction and thermal expansion tests revealed that Cu15Ni35Hf16.67Ti16.67Zr16.67 possesses high transformation temperature, narrow hysteresis temperature loops, and good dimensional stability within this HEA system.

Download Full-text

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

Metals ◽

10.3390/met10111531 ◽

2020 ◽

Vol 10 (11) ◽

pp. 1531

Author(s):

Yoko Yamabe-Mitarai

Keyword(s):

High Temperature ◽

Martensitic Transformation ◽

Shape Memory Alloys ◽

Shape Memory ◽

Transformation Temperature ◽

Ternary Alloys ◽

Alloying Elements ◽

Martensitic Transformation Temperature ◽

High Entropy ◽

Perfect Recovery

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.

Download Full-text

Martensitic Transformation of High-Entropy and Medium-Entropy Shape Memory Alloys

Materials Science Forum ◽

10.4028/www.scientific.net/msf.1016.1802 ◽

2021 ◽

Vol 1016 ◽

pp. 1802-1810

Author(s):

Hiromichi Matsuda ◽

Masayuki Shimojo ◽

Hideyuki Murakami ◽

Yoko Yamabe-Mitarai

Keyword(s):

Solid Solution ◽

High Temperature ◽

Martensitic Transformation ◽

Shape Memory Alloys ◽

Shape Memory ◽

Transformation Temperature ◽

Solid Solution Hardening ◽

Solution Hardening ◽

High Entropy ◽

The One

As new generation of high-temperature shape memory alloys, high-entropy alloys (HEAs) have been attracted for strong solid-solution hardened alloys due to their severe lattice distortion and sluggish diffusion. TiPd is the one potential high-temperature shape memory alloys because of its high martensitic transformation temperature above 500 °C. As constituent elements, Zr expected solid-solution hardening, Pt expected increase of transformation temperature, Au expected keeping transformation temperature, and Co expected not to form harmful phase. By changing the alloy composition slightly, two HEAs and two medium entropy alloys (MEAs) were prepared. Only two MEAs, Ti45Zr5Pd25Pt20Au5, and Ti45Zr5Pd25Pt20Co5 had the martensitic transformation. The perfect recovery was obtained in Ti45Zr5Pd25Pt20Co5 during the repeated thermal cyclic test, training, under 200 MPa. On the other hand, the small irrecoverable strain was remained in Ti45Zr5Pd25Pt20Au5 during the training under 150 MPa because of the small solid-solution hardening effect. It indicates that Ti45Zr5Pd25Pt20Co5 is the one possible HT-SMA working between 342 and 450 °C.

Download Full-text

Investigation on microstructure and martensitic transformation of neodymium-added NiTi shape memory alloys

Modern Physics Letters B ◽

10.1142/s0217984916502869 ◽

2016 ◽

Vol 30 (28) ◽

pp. 1650286

Author(s):

Dovchinvanchig Maashaa ◽

Ulzii-Orshikh Dorj ◽

Malrey Lee ◽

Min Hi Lee ◽

Chunwang Zhao ◽

...

Keyword(s):

Martensitic Transformation ◽

Shape Memory ◽

X Ray Diffraction ◽

Martensitic Transformation Temperature ◽

Scanning Calorimetry ◽

Nd Addition ◽

One Step ◽

Niti Shape Memory Alloys ◽

Niti Matrix ◽

Electronic Microscope

The effect of rare earth element neodymium (Nd) addition on the microstructure and martensitic transformation behavior of Ni[Formula: see text]Ti[Formula: see text]Nd[Formula: see text] ([Formula: see text] = 0, 0.1, 0.3, 0.5 and 0.7 at.%) shape memory alloy was investigated by scanning electronic microscope, X-ray diffraction and differential scanning calorimetry. The results show that the microstructure of Ni–Ti–Nd ternary alloy consists of NiNd phase, NiTi2 and the NiTi matrix. A one-step martensitic transformation is observed in the alloys. The martensitic transformation temperature Ms increases sharply increasing 0.1–0.7 at.% Nd content is added.

Download Full-text

A strategy of designing high-entropy alloys with high-temperature shape memory effect

Scientific Reports ◽

10.1038/s41598-019-49529-8 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 7

Author(s):

Je In Lee ◽

Koichi Tsuchiya ◽

Wataru Tasaki ◽

Hyun Seok Oh ◽

Takahiro Sawaguchi ◽

...

Keyword(s):

High Temperature ◽

Shape Memory ◽

Shape Memory Effect ◽

Memory Effect ◽

Noble Metals ◽

Alloy System ◽

Equilibrium Temperature ◽

High Entropy Alloys ◽

Face Centered Cubic ◽

High Entropy

Abstract Shape memory effect, the ability to recover a pre-deformed shape on heating, results from a reversible martensitic transformation between austenite and martensite phases. Here, we demonstrate a strategy of designing high-entropy alloys (HEAs) with high-temperature shape memory effect in the CrMnFeCoNi alloy system. First, we calculate the difference in Gibbs free energy between face-centered-cubic (FCC) and hexagonal-close-packed (HCP) phases, and find a substantial increase in thermodynamic equilibrium temperature between the FCC and HCP phases through composition tuning, leading to thermally- and stress-induced martensitic transformations. As a consequence, the shape recovery temperature in non-equiatomic CrMnFeCoNi alloys can be increased to 698 K, which is much higher than that of conventional shape memory alloys (SMAs) and comparable to that of B2-based multi-component SMAs containing noble metals (Pd, Pt, etc.) or refractory metals (Zr, Hf, etc.). This result opens a vast field of applications of HEAs as a novel class of cost-effective high-temperature SMAs.

Download Full-text

Effect of Aging on Phase Transition Behavior of Ti50Ni15Pd25Cu10 High Temperature Shape Memory Alloys

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1101.177 ◽

2015 ◽

Vol 1101 ◽

pp. 177-180 ◽

Cited By ~ 1

Author(s):

Saif Ur Rehman ◽

Mushtaq Khan ◽

Liaqat Ali ◽

Syed Husain Imran Jaffery

Keyword(s):

High Temperature ◽

Martensitic Transformation ◽

Shape Memory Alloys ◽

Shape Memory ◽

Martensite Phase ◽

Two Stage ◽

Transformation Temperatures ◽

Transition Behavior ◽

Forward Transformation ◽

Niti Shape Memory Alloys

Formation of Ni4Ti3 precipitates during aging of Ni-rich binary NiTi shape memory alloys and its effect on transition behavior during transformation from austenite to martensite phase has been studied extensively. However for equi-atomic NiTi-based quaternary high temperature shape memory alloy, two-stage martensitic transformation was detected for the first time. The Ti50Ni15Pd25Cu10 high temperature shape memory alloys were investigated for the hardness and transformation temperatures at aging temperature of 550°C. Aging at 550°C for 6 h resulted in remarkable increase in the hardness, whereas the phase transformation temperatures decreased significantly. During forward transformation from austenite to martensite, two-stage martensitic transformation; B2 (cubic) → R-phase and R-phase → B19 (orthorhombic) was observed.

Download Full-text