Structure And Martensitic Transformation in Ni44Mn43.5Sn12.5-xAlx Heusler Alloys

2013 ◽  
Vol 58 (2) ◽  
pp. 443-446 ◽  
Author(s):  
W. Maziarz ◽  
P. Czaja ◽  
T. Czeppe ◽  
A. Góral ◽  
L. Litynska-Dobrzynska ◽  
...  
Keyword(s):  
Martensitic Transformation ◽  
Heusler Alloys ◽  
Solution Treatment ◽  
Superlattice Reflection ◽  
Entropy Change ◽  
Peak Position ◽  
Scanning Calorimetry ◽  
Dsc Studies ◽  
Al Content ◽  
Diffraction Patterns

Alloys with constant Ni/Mn ratio equal to 1.01 of nominal compositions Ni44Mn43.5Sn12.5-xAlx (x = 0, 1, 2 and 3) were induction cast, homogenized in vacuum for 6 hours at 1000ºC, annealed for 1 h at 900 and water quenched for solution treatment (ST). Differential scanning calorimetry (DSC) studies revealed that the quenched alloys undergo martensitic transformation with martensite start temperatures (Ms) ranging from - 140 up to - 80ºC. An increase of Ms temperature with increasing of the aluminum content as well as the linear relationship between Ms and the conductive electron concentration (e/a) was observed. DSC has been used also to estimate the associated entropy change from the transformation heat Q and peak position temperature Tp; corresponding to ΔS ≈ Q/Tp. X-Ray diffraction phase analyses performed at room temperature proved that in all ST alloys the L21 Heusler structure is present. However, a different degree of order of this phase was observed, what was manifested by a decrease of intensity of the 111 superlattice reflection of the L21 structure with an increase of Al content. The ordering behavior was also proven by the transmission electron microscopy (TEM) investigations, particularly electron diffraction patterns. The evolution of microstructure after different treatments was also illustrated by light microscopy observations.

scholarly journals Martensitic Transformation and Crystalline Structure of Ni50Mn50−xSnx Melt-Spun Heusler Alloys

Crystals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 853
Author(s):  
Rim Ameur ◽  
Mahmoud Chemingui ◽  
Tarek Bachaga ◽  
Lluisa Escoda ◽  
Mohamed Khitouni ◽  
...  
Keyword(s):  
Martensitic Transformation ◽  
Room Temperature ◽  
Solidification Rate ◽  
Heusler Alloys ◽  
X Ray Diffraction ◽  
Key Factors ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Characteristic Temperatures ◽  
Melt Spun

The structure and thermal behavior are key factors that influence the functional response of Ni–Mn–Sn alloys. The present study reports the production as well as the structure and thermal analysis of melt-spun (solidification rate: 40 ms−1) Ni50 Mn50−xSnx (x = 10, 11, 12 and 13 at.%) alloys. X-ray diffraction measurements were performed at room temperature. The austenite state has an L21 structure, whereas the structure of the martensite is 7M or 10M (depending on the Sn/Mn percentage). Furthermore, the structural martensitic transformation was detected by differential scanning calorimetry (DSC). As expected, upon increasing the Sn content, the characteristic temperatures also increase. The same tendency is detected in the thermodynamic parameters (entropy and enthalpy). The e/a control allows the development production of alloys with a transformation close to room temperature.

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 External Fields on the Martensitic Transformation in Ni-Mn Based Heusler Alloys

2008 ◽  
Vol 52 ◽  
pp. 189-197 ◽  
Author(s):  
Xavier Moya ◽  
Lluís Mañosa ◽  
Antoni Planes ◽  
Seda Aksoy ◽  
Mehmet Acet ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Hydrostatic Pressure ◽  
Martensitic Transformation ◽  
Applied Magnetic Field ◽  
Heusler Alloys ◽  
Applied Pressure ◽  
Large Change ◽  
Entropy Change ◽  
Martensitic Transition ◽  
External Fields

In this paper, we discuss the possibility of inducing a martensitic transition by means of an applied magnetic field or hydrostatic pressure in Ni-Mn based Heusler shape memory alloys. We report on the shift of the martensitic transition temperatures with applied magnetic field and applied pressure and we show that it is possible to induce the structural transformation in a Ni50Mn34In16 alloy by means of both external fields due to: (i) the low value of the entropy change and (ii) the large change of magnetization and volume, which occur at the martensitic transition.

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

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 226
Author(s):  
Kousuke Nakamura ◽  
Atsushi Miyake ◽  
Xiao Xu ◽  
Toshihiro Omori ◽  
Masashi Tokunaga ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Martensitic Transformation ◽  
Spontaneous Magnetization ◽  
Heusler Alloys ◽  
Parent Phase ◽  
Entropy Change ◽  
Ferromagnetic State ◽  
Martensite Phase ◽  
Reverse Martensitic Transformation ◽  
Curie Temperatures

This study investigates the crystal structure, martensitic transformation behavior, magnetic properties, and magnetic-field-induced reverse martensitic transformation of Co64V15(Si21–xAlx) 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.

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

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1141
Author(s):  
Carlo Alberto Biffi ◽  
Jacopo Fiocchi ◽  
Mauro Coduri ◽  
Ausonio Tuissi
Keyword(s):  
Mechanical Properties ◽  
Martensitic Transformation ◽  
Binary Alloy ◽  
Room Temperature ◽  
Secondary Phase ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Al Content ◽  
Compressive Response ◽  
Al Addition

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)Zr50Alx 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.

Effect of Co substitution on the martensitic transformation and magnetocaloric properties of Ni50Mn35−xCoxSn15

2013 ◽  
Vol 28 (S1) ◽  
pp. S22-S27 ◽  
Author(s):  
F.S. Liu ◽  
Q.B. Wang ◽  
S.P. Li ◽  
W.Q. Ao ◽  
J.Q. Li
Keyword(s):  
Martensitic Transformation ◽  
Diffraction Analysis ◽  
Powder Diffraction ◽  
Magnetic Entropy Change ◽  
Magnetic Measurements ◽  
Entropy Change ◽  
Valence Electron Concentration ◽  
Magnetic Entropy ◽  
Scanning Calorimetry ◽  
X Ray

Martensitic transformation and magnetic entropy change in Co substituted Ni50Mn35−xCoxSn15 (x = 0, 1.0, 1.5, 2.0, and 3.0) Heusler alloys have been investigated by X-ray powder diffraction analysis, differential scanning calorimetry, and magnetic measurements. X-ray diffraction analysis reveals that the Ni50Mn35−xCoxSn15 alloys have L21 Heusler structure at room temperature. The phase decomposition of the sample with x = 3.0, after annealing 48 h at 1173 K, is confirmed by both X-ray powder diffraction analysis and energy-dispersive x-ray spectroscopy in scanning electron microscopy. With the increase of the Co content from 0 to 2.0, the martensitic transformation temperature TM increases from 185 to 245 K, which is in good agreement with the rule of valence electron concentration e/a-dependence of TM. The magnetic entropy change ∆SM is investigated in the vicinity of the martensitic transformation.

Martensitic transformation and mechanical properties of grain refined Ni–Co–Mn–Sn Heusler alloys via Cr doping

2021 ◽  
Vol 804 ◽  
pp. 140777
Author(s):  
Yajiu Zhang ◽  
S. Vinodh Kumar ◽  
Wanwan Xiang ◽  
Zhigang Wu ◽  
Zuoyu Sun
Keyword(s):  
Mechanical Properties ◽  
Martensitic Transformation ◽  
Heusler Alloys ◽  
Cr Doping

Identification of Amber and the Copal under Heat Pressurized Process

2012 ◽  
Vol 554-556 ◽  
pp. 2112-2115
Author(s):  
Hui Li ◽  
Xuan Wang ◽  
Yong Zhu ◽  
Qin Ren
Keyword(s):  
Chemical Properties ◽  
Peak Position ◽  
Exothermic Peak ◽  
Endothermic Peak ◽  
Scanning Calorimetry ◽  
Natural Resin ◽  
Before And After ◽  
Artificial Heat ◽  
Physical And Chemical ◽  
And Chemical Properties

Amber and copal belong to the natural resin, which are similar and transitional in the physical and chemical properties. The artificial heat-pressurized treatment is contributed to the polymerization of the natural copal, and turns into green, yellow-green and deep orange-yellow copal. It is very difficult to identify amber from the heat- pressurized treatment copal only based on the gemological parameters.The thermal behavior of amber and the copal before and after heat-pressurized treatment were analyzed by means of differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy(FTIR) and nuclear magnetic resonance(NMR). The results show that amber exists an evident endothermic peak around 123~132°C, and copal reveals an obvious endothermic peak at about 174~178°C, and the heat pressurized treatment copal occurs a clear exothermic peak around 150~152°C. The differences between endothermic or exothermic transition and peak position reveal occurring thermal oxidation or the bond breaking or the melting, which are of great significance in the identification.

Mechanical and microstructural properties of polystyrene based composites: positron lifetime spectroscopic and DSC studies

2011 ◽  
Vol 31 (2-3) ◽  
Author(s):  
Abdullah Mohammed Ali Mohammed Altaweel ◽  
Jaya Madhu Raj ◽  
Malalvalli Nagarajaiah Chandrashekara ◽  
Puttegowda Ramya ◽  
Parthasarathy Sampathkumaran ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Free Volume ◽  
Positron Lifetime ◽  
Tensile Modulus ◽  
Silica Content ◽  
Scanning Calorimetry ◽  
Dsc Studies ◽  
Microstructural Property ◽  
Calcium Aluminosilicate

Abstract Polystyrene (PS) based composites respectively with cenosphere (CS) and calcium aluminosilicate (CAS) as fillers were studied using the positron lifetime technique to reveal the correlation between free volume, a microstructural property, and mechanical properties of the composites (tensile strength and tensile modulus). The thermal stability of the composites was determined using differential scanning calorimetry. The results showed that addition of CAS filler lead to a significant improvement in the mechanical properties of the composite, whereas addition of CS resulted in improvement in tensile modulus only. Both PS/CAS and PS/CS composites showed enhancement in thermal stability compared with that of the pure PS matrix. The positron results showed that the average free volume size for the PS/CAS composite (at 40 phr CAS) was reduced significantly compared with that of the pure PS. These results are understood in terms of the influence of silica content, filler-matrix interaction, and particle size.

Effect of Electroplastic Deformation on Martensitic Transformation in Coarse Grained and Ultrafine Grained Ni-Ti Shape Memory Alloy

2008 ◽  
Vol 584-586 ◽  
pp. 127-132 ◽  
Author(s):  
Anastasia E. Sergeeva ◽  
Daria Setman ◽  
Michael Zehetbauer ◽  
Sergey Prokoshkin ◽  
Vladimir V. Stolyarov
Keyword(s):  
Differential Scanning Calorimetry ◽  
Martensitic Transformation ◽  
Shape Memory Alloy ◽  
Cold Rolling ◽  
Shape Memory ◽  
Coarse Grained ◽  
Scanning Calorimetry ◽  
Structure Relaxation ◽  
Differential Scanning Calorimetry Method ◽  
Ultrafine Grained

The aim of this paper is the investigation of electroplastic deformation (EPD) and subsequent annealing influence on martensitic transformation in the shape memory Ni50.7Ti49.3 alloy. Using differential scanning calorimetry method it was shown that EPD at the low strain stimulates structure relaxation and recovers martensitic transformation in cooling, which is usually suppressed by cold rolling.

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