Processing and Characterization of Cu-Al-Ni Shape Memory Alloy Strips Prepared from Elemental Powders via a Novel Powder Metallurgy Route

Sharma, Mohit; Vajpai, Sanjay Kumar; Dube, R. K.

doi:10.1007/s11661-010-0351-y

Cited by 16 publications

(8 citation statements)

References 17 publications

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“…The reason behind the fact that a transformation was observed in the epitaxially grown (200) textured austenite thin film whereas no change was seen in the randomly oriented polycrystalline one could be related to size effects. Size effects, such as the volume of the material or structural components including precipitate particles and grains in polycrystals, have a huge influence on the martensitic phase transformation [37]. Decreasing grain size and decreasing twin separation cause an increase in strain energy and twin interfacial energy which, in turn, increases the energy barrier [38].…”

Section: Resultsmentioning

confidence: 99%

Epitaxial Versus Polycrystalline Shape Memory Cu-Al-Ni Thin Films

et al. 2019

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In this work, two different approaches were followed to obtain Cu-Al-Ni thin films with shape memory potential. On the one hand, Cu-Ni/Al multilayers were grown by magnetron sputtering at room temperature. To promote diffusion and martensitic/austenitic phase transformation, the multilayers were subjected to subsequent heat treatment at 800 °C and quenched in iced water. On the other hand, Cu, Al, and Ni were co-sputtered onto heated MgO (001) substrates held at 700 °C. Energy-dispersive X-ray spectroscopy, X-ray diffraction, and transmission electron microscopy analyses were carried out to study the resulting microstructures. In the former method, with the aim of tuning the thin film’s composition, and, consequently, the martensitic transformation temperature, the sputtering time and applied power were adjusted. Accordingly, martensitic Cu-14Al-4Ni (wt.%) and Cu-13Al-5Ni (wt.%) thin films and austenitic Cu-12Al-7Ni (wt.%) thin films were obtained. In the latter, in situ heating during film growth led to austenitic Cu-12Al-7Ni (wt.%) thin films with a (200) textured growth as a result of the epitaxial relationship MgO(001)[100]/Cu-Al-Ni(001)[110]. Resistance versus temperature measurements were carried out to investigate the shape memory behavior of the austenitic Cu-12Al-7Ni (wt.%) thin films produced from the two approaches. While no signs of martensitic transformation were detected in the quenched multilayered thin films, a trend that might be indicative of thermal hysteresis was encountered for the epitaxially grown thin films. In the present work, the differences in the crystallographic structure and the shape memory behavior of the Cu-Al-Ni thin films obtained by the two different preparation approaches are discussed.

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Section: Resultsmentioning

confidence: 99%

Epitaxial Versus Polycrystalline Shape Memory Cu-Al-Ni Thin Films

et al. 2019

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“…This diffractogram shows many peaks suggesting a multi-phase alloy. In this diffractogram, there are the peaks of the Al, the peaks of CuNi [14,44], the peaks of NiAl [45,46] and those of the austenite phase of the Cu-based SMAs [47,48].…”

Section: Characterization Of the Superelasticitymentioning

confidence: 99%

Production and Mechanical Properties of Cu-Al-Ni-Be Shape Memory Alloy Thin Ribbons Using a Cold Co-Rolled Process

Peltier

Perroud

Moll

et al. 2021

Shap. Mem. Superelasticity

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The use of shape memory alloys for micro-actuators constitutes a field of application in which copperaluminum-based alloys find their usefulness because they can reach higher activation temperatures and are easier to produce than titanium-based alloys, particularly by the method proposed in this work. SMA tapes are a two-dimensional structure that offers many design options such as stamping, punching, and deep drawing, but they are also suitable for laser cutting, engraving, stamping, and EDM machining. This work has been made to study the manufacture of copper-based shape memory alloys (SMAs) using the cold co-rolling process also called the cold-roll bonding (CRB) process. In this process, a thin metal sandwich can be produced with a rolling machine. This sandwich consists of layers of CuNiBe master alloy and Al. During the rolling phase, the sandwich has no shape memory effect (SME) or superelastic effect (SE), so thin strips can be easily produced. After the rolling phase, the sandwich is subjected to a complex heat treatment to gain the SME. To validate this process to produce Cu-based SMAs, several alloys with different CuAlNiBe compositions have been tested. The SMAs obtained were characterized by optical microscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The martensitic transformation was studied by Differential Scanning Calorimetry (DSC) and SME and SE were studied by three-point bending tests. This work shows that the CRB is a good process for making a wide variety of Cu-based SMA ribbons.

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“…This makes the process more time consuming and economically unviable. 22 Recently, Vajpai et al 23 have prepared SMA strips by the milling of the elemental powder mixture for a shorter duration (8 h) followed by secondary processing. However, it was observed that the homogenisation treatments required much longer time to produce chemically homogeneous strips.…”

Section: Introductionmentioning

confidence: 99%

Effect of milling parameters on processing, microstructure and properties of Cu–Al–Ni–Ti shape memory alloys

et al. 2015

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The effect of milling parameters, such as ball/powder ratio (BPR), milling speed and time, on the microstructural and phase development of powder metallurgy processed Cu-Al-Ni-Ti shape memory alloys has been studied. It has been found that milling for 40 h at a BPR of 40:1, 200 rev min -1 is the optimised condition for mechanical alloying in an attritor mill in order to get a uniform distribution of the alloying elements. A lower BPR caused insufficient milling, whereas a higher BPR led to oxidation of the powder. The complete formation of martensite occurred in the sample prepared under the optimised milling condition followed by cold compaction, sintering at 9008C for 1 h in vacuum and finally quenching. The austenite transformation temperature of the prepared shape memory alloy was found to be ,2088C. Thus, the developed process enables to curtail the long milling time as well as decrease the prolonged homogenisation treatments.

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Processing and Characterization of Cu-Al-Ni Shape Memory Alloy Strips Prepared from Elemental Powders via a Novel Powder Metallurgy Route

Cited by 16 publications

References 17 publications

Epitaxial Versus Polycrystalline Shape Memory Cu-Al-Ni Thin Films

Epitaxial Versus Polycrystalline Shape Memory Cu-Al-Ni Thin Films

Production and Mechanical Properties of Cu-Al-Ni-Be Shape Memory Alloy Thin Ribbons Using a Cold Co-Rolled Process

Effect of milling parameters on processing, microstructure and properties of Cu–Al–Ni–Ti shape memory alloys

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