scholarly journals Microstructure and Martensitic Transformation Behavior in Thermal Cycled Equiatomic CuZr Shape Memory Alloy

Metals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 580 ◽  
Author(s):  
Shota Hisada ◽  
Mitsuhiro Matsuda ◽  
Minoru Nishida ◽  
Carlo Biffi ◽  
Ausonio Tuissi
Keyword(s):  
Martensitic Transformation ◽  
Thermal Cycling ◽  
Parent Phase ◽  
Reverse Transformation ◽  
Maximum Temperature ◽  
Transformation Behavior ◽  
High Temperature Side ◽  
Scanning Calorimetry ◽  
Transmission Electron ◽  
Multiple Structures

Equiatomic CuZr alloy undergoes a martensitic transformation from the B2 parent phase to martensitic phases (P21/m and Cm) below 150 °C. We clarified the effect of the thermal cycling on the morphology and crystallography of martensite in equiatomic CuZr alloy using a transmission electron microscopy. The 10th cycled specimens consisted of different multiple structures at the maximum temperature of differential scanning calorimetry (DSC) measurement −400 °C and 500 °C, respectively. At the maximum temperature 400 °C of DSC measurement, it is composed of the fine plate-like variants, and a lamellar eutectoid structure consisting of Cu10Zr7 and CuZr2 phases on the martensitic variant. Concerning the maximum temperature of 500 °C of DSC measurement, it is observed the martensitic structure and the lamellar structure in which the martensitic phase was completely eutectoid transformed. The formation of this lamellar eutectoid structure, due to thermal cycling leads to the shift of forward and reverse transformation peaks to low and high temperature side. In addition, new forward and reverse transformation peaks indicating a new transformation appeared by thermal cycling, and the peaks remained around −20 °C. This new martensitic transformation behavior is also discussed.

scholarly journals Microstructure and Martensitic Transformation Behavior in Thermal Cycled Equiatomic Cuzr Shape Memory Alloy

2019 ◽  
Author(s):  
Shota Hisada ◽  
Mitsuhiro Matsuda ◽  
Minoru Nishida ◽  
Carlo Alberto Biffi ◽  
Ausonio Tuissi
Keyword(s):  
Martensitic Transformation ◽  
Thermal Cycling ◽  
Parent Phase ◽  
Reverse Transformation ◽  
Maximum Temperature ◽  
Transformation Behavior ◽  
High Temperature Side ◽  
Transmission Electron ◽  
Multiple Structures ◽  
Temperature Side

Equiatomic CuZr alloy undergoes a martensitic transformation from the B2 parent phase to martensitic phases (P21/m and Cm) below 150 °C. We clarified the effect of the thermal cycling on the morphology and crystallography of martensite in equiatomic CuZr alloy using a transmission electron microscopy. The 10th cycled specimens consisted of different multiple structures at the maximum temperature of DSC measurement: 400 °C and 500°C, respectively. At the maximum temperature 400 °C of DSC measurement, it is composed of the fine plate-like variants, and a lamellar eutectoid structure consisting of Cu10Zr7 and CuZr2 phases on the martensitic variant. Concerning the maximum temperature 500 °C of DSC measurement, it is observed the martensitic structure and the lamellar structure in which the martensitic phase was completely eutectoid transformed. The formation of this lamellar eutectoid structure due to thermal cycling leads to the shift of forward and reverse transformation peaks to low and high temperature side. In addition, new forward and reverse transformation peaks indicating a new transformation appeared by thermal cycling, and the peaks remained around -20 °C. This new martensitic transformation behavior is also discussed.

Transformation Behavior of TiNiPt Thin Films Fabricated Using Melt Spinning Technique

2004 ◽  
Vol 842 ◽  
Author(s):  
Tomonari Inamura ◽  
Yohei Takahashi ◽  
Hideki Hosoda ◽  
Kenji Wakashima ◽  
Takeshi Nagase ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Martensitic Transformation ◽  
Heat Treatment Temperature ◽  
Melt Spinning ◽  
Bulk Material ◽  
Parent Phase ◽  
Treatment Temperature ◽  
Transformation Behavior ◽  
Scanning Calorimetry ◽  
Similar Chemical

ABSTRACTMartensitic transformation behavior of Ti50Ni40Pt10 (TiNiPt) melt-spun ribbons were investigated where the heat treatment temperature was systematically changed from 473K to 773K. A hot-forged bulk TiNiPt material with the similar chemical composition was also tested as a comparison. θ-2θ X-ray diffraction analysis and transmission electron microscopy observation revealed that the as-spun ribbons were fully crystallized. The apparent phases of as-spun ribbons at room temperature are both B19 martensite and B2 parent phase instead of B2 single phase for the hot-forged bulk material. No precipitates were found in as-spun and heat-treated ribbons. It was revealed by differential scanning calorimetry that all the specimens exhibit one-step transformation. The martensitic transformation temperatures of the TiNiPt as-spun ribbons are 100K higher than those of the hot-forged bulk material, and the martensitic transformation temperature decreases with increasing heat treatment temperature.

HYPERSTABILIZATION OF MARTENSITES

2012 ◽  
Vol 05 (01) ◽  
pp. 1250005 ◽  
Author(s):  
SERGEY KUSTOV ◽  
RUBEN SANTAMARTA ◽  
DANIEL SALAS ◽  
EDUARD CESARI ◽  
KONSTANTIN SAPOZHNIKOV ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Internal Friction ◽  
Parent Phase ◽  
Reverse Transformation ◽  
High Concentration ◽  
Scanning Calorimetry ◽  
Internal Friction Peak ◽  
Transmission Electron ◽  
Interphase Boundaries

The effect of hyperstabilization of martensite implies that the reverse martensitic transformation proceeds in two well separated stages. Namely, a small fraction of martensite (of the order of 10%) retransforms upon heating into the parent phase over a temperature range slightly higher than the nominal reverse transformation temperature, whereas the rest of the martensite retransforms through a re-nucleation of fine lamellae of the parent phase. The renucleation stage of the transformation is well defined and requires strong overheating of the order of 300 K with respect to the nominal transformation. In this letter, the results are discussed of a study of the hyperstabilization effect in different martensitic structures: faulted [Formula: see text] martensite in Cu–Al–Be system and twinned martensite in ferromagnetic Ni–Fe–Ga crystals by means of differential scanning calorimetry, transmission electron microscopy and internal friction. The conclusion has been drawn that hyperstabilization implies a severe blocking of the motion of interphase boundaries during the reverse transformation, which can be produced either due to a high concentration of highly mobile quenched-in defects ("sweeping" of defects during the reverse transformation) or due to a creation of obstacles by preliminary plastic deformation. The former mechanism requires very intense diffusion of quenched-in defects assisted by dislocations/interfaces, which has been confirmed by internal friction studies. It has been shown that the renucleation stage, which occurs at around 600 K for different alloys, is preceded by a relaxation internal friction peak. A possible role of this relaxation in renucleation of the parent phase is discussed.

Martensitic Transformation and Shape Memory Effect of Ni53.25Mn21.75Ga25 Ferromagnetic Shape Memory Alloy

2012 ◽  
Vol 476-478 ◽  
pp. 1504-1507
Author(s):  
Hai Bo Wang ◽  
Shang Shen Feng ◽  
Pei Yang Cai ◽  
Yan Qiu Huo
Keyword(s):  
Magnetic Field ◽  
Martensitic Transformation ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Parent Phase ◽  
Transformation Strain ◽  
Scanning Calorimetry ◽  
Reversible Transformation ◽  
Ferromagnetic Shape Memory

The martensitic transformation, crystalline structure, microstructure and shape memory effect of the Ni53.25Mn21.75Ga25 (at.%) alloy are investigated by means of Differential Scanning Calorimetry (DSC), X-ray diffraction (XRD), Transmission Electron Microscope (TEM) and the standard metal strain gauge technique. The XRD results showed that the Ni53.25Mn21.75Ga25 alloy is composed of cubic parent phase at room temperature. TEM observation proved that the typical twin martensite is tetragonal structure and tweed-like contrast which is typical image for the parent phase. A large reversible transformation strain, about 0.54%, is obtained in this undeformed polycrystalline alloy due to martensitic transformation and its reverse transformation. This transformation strain is also increased to 0.65% by the external magnetic field. It is believed that the effect of the magnetic field on the preferential orientation of martensitic variants increases the transformation strain.

Reverse transformation behavior of TiNi shape memory alloys prestrained in the parent phase

2006 ◽  
Vol 21 (3) ◽  
pp. 26-28
Author(s):  
Huai Limin ◽  
Cui Lishan ◽  
Zhang Yaibin ◽  
Zheng Yanjun ◽  
Han Xiangli
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Parent Phase ◽  
Reverse Transformation ◽  
Transformation Behavior

Aging Effects of Cu-Zn-Al Shape Memory Alloys Studied by the Alchemi Measurements

1991 ◽  
Vol 246 ◽  
Author(s):  
K. Shimizu ◽  
Y. Nakata ◽  
O. Yamamoto
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Parent Phase ◽  
Stacking Faults ◽  
Martensite Phase ◽  
Reverse Transformation ◽  
Aging Effects ◽  
Scanning Calorimetry ◽  
Martensite Stabilization ◽  
Cu And Zn

AbstractThe aging effects of two kinds of Cu-Zn-Al shape memory alloys (Cu-ll.4 Zn-18.7A1 (A) and Cu-ll.2Zn-17.lAl (B) in at%) have been examined by differential scanning calorimetry (DSC), transmission electron microscopy (TEM) and atom location by channeling enhanced microanalysis (ALCHEMI). In the directly quenched (D.Q.) state, alloy A was the parent phase, Ms being 253 K, and alloy B was the martensite phase. The alloy B was subjected another quenching treatment as follows: It was once quenched into an oil bath at 423 K and held for 300 s, followed by quenching into iced water (step quench (S.Q.) ). The D.Q. alloy B did not exhibit the reverse transformation because of a stabilization of the martensbite phase, but the S.Q. alloy B did and its As temperature of the reverse transformation was raised with the progress of aging at the martensitic state. Fraction of Zn atoms at the Cu(2) site examined by the ALCHEMI measurements was almost the same in the parent phase of D.Q. alloy A and its aged one, indicating no change in Cu and Zn atom sites, while it was gradually decreased in S.Q. alloy B with the progress of aging. The fraction of Zn atoms in D.Q. alloy B was much lower than those in the S.Q. alloy B and its aged one. TEM observation of the S.Q. alloy B revealed that stacking faults as the lattice invariant shear in the M18R martensites decreased in the density with the progress of aging. The decrease in the fraction of Zn atoms and in the density of stacking faults well corresponds to the increase in As temperature, and thus the martensite stabilization was attributed to a disordering between Cu and Zn atoms and to an annihilation of stacking faults.

Structure and Martensitic Transformation in NiMnSn Alloy Ribbons with Partial Sn Substitution by Al

2013 ◽  
Vol 203-204 ◽  
pp. 232-235 ◽  
Author(s):  
Wojciech Maziarz ◽  
Paweł Czaja ◽  
Marek Faryna ◽  
Tomasz Czeppe ◽  
Anna Góral ◽  
...  
Keyword(s):  
Martensitic Transformation ◽  
Melt Spinning ◽  
Parent Phase ◽  
Unit Cell ◽  
Unit Cell Parameters ◽  
Scanning Calorimetry ◽  
Cell Parameters ◽  
Al Content ◽  
Dsc Measurements ◽  
Profile Fitting

The influence of Al substitution for Sn in Ni44Mn43.5AlxSn12.5-x(x= 0, 1, 2, 3) ferromagnetic shape memory alloy ribbons on phase transformation and microstructure evolution is outlined in this paper. Ribbons produced by melt spinning technique showed fully crystalline structure, however non uniform. Energy dispersive spectroscopy microanalysis (EDS) confirmed the average composition of ribbons in accord with the initial alloys. The higher symmetry parent phase was identified with the aid of X-ray diffraction (XRD) as bcc L21Heusler type structure. The unit cell parameters were determined applying the XRD profile fitting method. It was observed that with increase of Al content unit cell parameters and in turn unit cell volume decrease. This may be attributed to the fact that Al has a smaller radius compared to Sn, which it was substituted for. Differential scanning calorimetry (DSC) measurements did not allow to detect the martensitic transformation above -150°C.

Effect of Ce Addition on Martensitic Transformation Behavior of TiNi Shape Memory Alloys

2005 ◽  
Vol 475-479 ◽  
pp. 1973-1976 ◽  
Author(s):  
Ailian Liu ◽  
Xianglong Meng ◽  
Wei Cai ◽  
Lian Cheng Zhao
Keyword(s):  
Differential Scanning Calorimetry ◽  
Phase Transformation ◽  
Martensitic Transformation ◽  
Shape Memory ◽  
Energy Dispersive Spectroscopy ◽  
Transformation Temperature ◽  
Martensitic Transformation Temperature ◽  
Transformation Behavior ◽  
Scanning Calorimetry ◽  
Ce Content

The effect of cerium addition on the martensitic transformation behavior and microstructure of Ti50-x/2Ni50-x/2Cex (x=0, 0.5, 2, 5 and 10at.%) alloys have been studied by differential scanning calorimetry (DSC) and energy dispersive spectroscopy (EDS). The results show that the addition of cerium affects the martensitic transformation temperature obviously. With the increase of Ce content, the phase transformation temperatures first increase rapidly and then decrease slightly, which may be attributed to the change of the Ni/Ti ratio in matrix. Moreover, the dispersed Ce-riched second particles with various morphologies are observed in TiNiCe alloys.

The Effect of Reverse Transformation on Recovery • Recrystallization Process in Ti-Pd-Ni High Temperature Shape Memory Alloys

1996 ◽  
Vol 459 ◽  
Author(s):  
Ya Xu ◽  
Kazuhiro Otsuka ◽  
Tatsuhiko Ueki ◽  
Kengo Mitose
Keyword(s):  
High Temperature ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Parent Phase ◽  
Hardness Test ◽  
Reverse Transformation ◽  
Atomic Diffusion ◽  
Recrystallization Process ◽  
Scanning Calorimetry ◽  
Heating Treatment

ABSTRACTThe effect of martensitic reverse transformation on recovery • recrystallization process in cold rolled Ti-Pd-Ni high temperature shape memory alloys has been investigated systematically by flash heating treatment, micro-Vickers hardness test, differential scanning calorimetry and transmission electron microscopy. It was found that the temperatures of softening in hardness after flash heating treatments agree well with the reverse transformation temperatures in the present alloys, and most of the softening occurs within 60 seconds when annealing temperature is raised to above the reverse transformation temperature. We conclude that the recovery • recrystallization process is controlled by the reverse transformation. The reasons are considered based on the large difference in atomic diffusion rate in the parent phase and in the martensite.

Martensitic Transformation of TiAu Shape Memory Alloys

2007 ◽  
Vol 561-565 ◽  
pp. 1541-1544 ◽  
Author(s):  
Hideki Hosoda ◽  
Ryosuke Tachi ◽  
Tomonari Inamura ◽  
Kenji Wakashima ◽  
Shuichi Miyazaki
Keyword(s):  
Martensitic Transformation ◽  
Shape Memory ◽  
Parent Phase ◽  
Stoichiometric Composition ◽  
Transformation Strain ◽  
Martensite Phase ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Rich Side

Martensitic transformation temperatures were measured and transformation strains were evaluated in a promising high temperature shape memory alloy TiAu with a compositional range from 46 to 53mol%Au. It was found by differential scanning calorimetry that martensitic transformation start temperature (Ms) is kept almost constant value of 880K in the Au-rich side of the stoichiometric composition. On the other hand, Ms decreases monotonically with decreasing Au content in the Au-poor side. X-ray diffraction analysis revealed that apparent phase of all the alloys at room temperature is B19 martensite phase. Under an assumption that the atomic volume is constant during martensitic transformation, the lattice parameters of B2 parent phase and maximum transformation strain were calculated. It was found that the maximum transformation strain depends on chemical composition and that it reaches 10.75% for Ti-53mol%Au alloy. The value is comparable to that of Ti-Ni.

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