Journal ArticleDOI
Calorimetry in Cu–Zn–Al alloys under different structural and microstructural conditions
J.L. Pelegrina,Ricardo Romero +1 more
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In this article, the authors performed a detailed analysis on four kinds of Cu-Zn-Al samples, arising from the combination of different martensitic structures and from the presence or not of grain boundaries.Abstract:
Calorimetric measurements have been carefully performed on four kinds of Cu–Zn–Al samples, arising from the combination of different martensitic structures and from the presence or not of grain boundaries. The differences found in the transformation behaviour, characteristic transformation temperatures and in the corresponding thermodynamic properties (enthalpy and entropy changes) have been analyzed. The remarkable finding was that the transformation to 2H in the polycrystalline samples couldn’t go on completion. On the other hand, this behaviour was not observed for the transition to 18R, within the experimental scatter.read more
Citations
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Entropy change at the martensitic transformation in ferromagnetic shape memory alloys Ni2+xMn1−xGa
TL;DR: In this paper, the entropy change ΔS between the high-temperature cubic phase and the lowtemperature tetragonally based martensitic phase of Ni2+xMn1−xGa (x=0-020) alloys was studied.
Journal ArticleDOI
Grain size and pseudoelastic behaviour of a Cu–Al–Be alloy
TL;DR: The effect of grain size on the pseudoelastic behavior of a Cu-11.4.% Al-0.5 wt.% Be shape memory alloy was studied in this article, where Annealing at 1073 K leads to grain growth with a kinetic exponent around 0.5.
On the stability of the bcc phase in Cu-Al-Mn shape memory alloys
TL;DR: In this article, the authors measured the entropy change at the martensitic transition of two composition-related sets of shape-memory alloys and found that most of the change has a vibrational origin, and depends only on the particular close-packed structure of the low-temperature phase.
Journal ArticleDOI
Effects of thermal treatments on transformation behaviour in shape memory Cu-Al-Ni alloys
TL;DR: In this article, the effects of various quenching, up-quenching and step quenchings in a water bath 100 °C and in an oil bath at 200 °C have been studied on two shape memory Cu-Al-Ni alloys.
Journal ArticleDOI
On the Stress-Induced Formation of R-Phase in Ultra-Fine-Grained Ni-Rich NiTi Shape Memory Alloys
TL;DR: In this article, the formation of the R-phase of binary ultra-fine-grained (UFG) NiTi wires was studied in a wide temperature range using mechanical loading/unloading experiments, resistance measurements, differential scanning calorimetry (DSC), thermal infrared imaging, and transmission electron microscopy (TEM).
References
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On the thermodynamics of thermoelastic martensitic transformations
R.J. Salzbrenner,Morris Cohen +1 more
TL;DR: In this paper, both elastic strain energy due to the transformational shape change and frictional resistance opposing interfacial motion are shown to contribute significantly to the observed thermodynamic changes which accompany thermoelastic martensitic transformations in Cu-14 Al-2.5 Ni alloys.
Journal ArticleDOI
Thermodynamic analysis of thermal measurements in thermoelastic martensitic transformations
Jordi Ortín,Antoni Planes +1 more
TL;DR: In this article, the thermodynamics of thermoelastic martensitic transformations are reformulated from the point of view of calorimetric experiments, and it is shown that the heat released or absorbed by the specimen is due to a triple contribution: the latent heat of transformation, the reversibly stored elastic enthalpy and the irreversible work mainly spent in moving the interfaces.
Journal ArticleDOI
The influence of short-range disorder on te martensitic transformation in CuZn and CuZnAl alloys
R. Rapacioli,M. Ahlers +1 more
TL;DR: In this paper, it was shown that quenched-in disordered atom pairs in the long-range ordered matrix can increase the transformation temperature of alloys, and the formation energies for disordered pairs have been calculated.
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