Aging response and its effect on the functional properties of Cu–Al–Ni shape memory alloys

Suresh, N.; Ramamurty, U.

doi:10.1016/j.jallcom.2006.02.094

Cited by 77 publications

(36 citation statements)

References 20 publications

(44 reference statements)

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“…This means that during rapid cooling, the high-temperature bphase is expanded into a L2 1 -ordered structure and can further be transformed into a martensite phase of 18R 14].To analyze the crystallite size on the transformation temperatures of the alloys, we calculated crystallite size for the alloys. For this, we used the following relation [15,16]:…”

Section: Methodsmentioning

confidence: 99%

New type of Schottky diode-based Cu–Al–Mn–Cr shape memory material films

et al. 2016

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Cr-doped CuAlMn shape memory alloys were produced by arc melting method. The effects of Cr content on microstructure and transformation parameters of were investigated. The alloys were characterized by X-ray analysis, optical microscope observations and differential scanning calorimetry measurements. The grain size of the alloys was decreased by the addition of Cr into CuAlMn alloy system. The martensite transformation temperature was shifted both the lower temperature and higher temperature with the addition of chromium. This change was explained on the basis of the change in the thermodynamics such as enthalpy, entropy and activation energy values. The obtained results indicate that the phase transformation temperatures of the CuAlMn alloy system can be controlled by addition of Cr. We fabricated a Schottky barrier diode and observed that ideality factor and barrier height increase with increasing temperature. The diodes exhibited a thermal sensor behavior. This indicates that Schottky diode-based Cu-Al-Mn-Cr shape memory material films can be used as a sensor in high-temperature measurement applications.

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Section: Methodsmentioning

confidence: 99%

New type of Schottky diode-based Cu–Al–Mn–Cr shape memory material films

et al. 2016

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“…As can be observed from Fig. 2a, the cooling curves have multi-peaks, which are attributed to the inner stress and/or precipitate coarsening caused by the inhomogeneity process [27]. The thermodynamic parameters of forward and reverse transition of the aged Cu-Al-Ni-xTi (x = 0.4, 0.7 and 1.0 mass%) SMAs were determined and are presented in Fig.…”

Section: Dsc Analysismentioning

confidence: 93%

X-phase precipitation in aging of Cu–Al–Ni–xTi shape memory alloys and its influence on phase transition behavior

Saud

Hamzah

Abubakar

et al. 2015

J Therm Anal Calorim

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The present work aims to investigate the aging treatment effects on the microstructure, transition characteristics, and mechanical properties of Cu-Al-Ni-xTi shape memory alloys. The aging treatment of the homogenized and modified alloys of Cu-Al-Ni-xTi results in variations of the martensite morphology, volume fraction, and precipitate size. These variations in the features of precipitates have an obvious effect on transition behavior and mechanical properties. The transition temperatures are increased slightly with an increase in the aging time and temperatures; such increase is mainly attributed to changes in the c 0 1 and b 0 1 morphology and distribution, along with the precipitates. The thermodynamic parameters (DH and DS) tend to decrease with an increase in the aging time and temperatures. Moreover, the brittleness, low strength, and poor processability of Cu-Al-Ni alloys greatly limit their application. We attempted to improve the mechanical properties without losing the thermoelastic properties through the additions of Ti and appropriate aging treatments. The highest tensile strength and strain of 640 MPa and 4.3 % were obtained in alloy of Cu-Al-Ni-0.7 mass% Ti aged at 250°C for 24 h and 100°C for 48 h, respectively. The shape memory behavior of the alloys was studied using a specially designed machine. The strain recovery by shape memory effect of the alloys increases with an increase in the aging tomes and temperature, where the highest recovery (100 %) is obtained with the alloy of Cu-Al-Ni-0.7 mass% Ti after being aged at 250°C for 24 h.

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“…The total area under the curve was expressed as the value of the enthalpy ( H ), while the value of the entropy was equal to the value of enthalpy changes divided by the equilibrium temperature. The argumentation of Salzbnenner and Cohen was used to determine the value of the T 0 equilibrium temperature between the martensite and austenite phases by the following equation [24][25][26][27][28]:…”

Section: Structural Propertiesmentioning

confidence: 99%

Investigation of the Enthalpy/Entropy Variation and Structure of Cu–Al–Mn–Fe Shape Memory Alloys

2015

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Cu-based Cu-Al-Mn-Fe shape memory alloys were produced in an arc melter under vacuum. The crystal structure of the fabricated alloys were determined by means of X-ray diffraction (XRD). The XRD analysis results indicated that the martensitic phase of the samples have an M18R structure. The characteristic transformation temperatures, thermodynamic parameters, and the activation energy values of the samples according to Kissinger and Ozawa methods were determined by differential scanning calorimetry measurements. The austenite transformation temperatures (A s ) of the samples were found as 149.52 • C, 128.52 • C, and 103.86 • C, respectively. Also, the calculated activation energy values of the samples according to Kissinger and Ozawa methods are compared with each other. The effect of the presence of Al and Fe in the samples on the thermodynamic parameters is studied in this work.

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Aging response and its effect on the functional properties of Cu–Al–Ni shape memory alloys

Cited by 77 publications

References 20 publications

New type of Schottky diode-based Cu–Al–Mn–Cr shape memory material films

New type of Schottky diode-based Cu–Al–Mn–Cr shape memory material films

X-phase precipitation in aging of Cu–Al–Ni–xTi shape memory alloys and its influence on phase transition behavior

Investigation of the Enthalpy/Entropy Variation and Structure of Cu–Al–Mn–Fe Shape Memory Alloys

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