Ageing in Parent Phase and Martensite Stabilization in a Ni&lt;SUB&gt;50&lt;/SUB&gt;Ti&lt;SUB&gt;30&lt;/SUB&gt;Hf&lt;SUB&gt;20&lt;/SUB&gt; Alloy

Manca, A.; Shelyakov, A. V.; Airoldi, G.

doi:10.2320/matertrans.44.1219

Cited by 7 publications

(3 citation statements)

References 12 publications

(16 reference statements)

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“…In Ti-Pd and Ti-Pd-Ni HTSMAs, martensite aging effect has been shown to be highly dependent on composition [61] as substitution of Pd by Ni increases the total concentration of anti-site defects (ASD). Similar martensite aging has been observed in Co-Ni-Ga [62] and Ni-Ti-Hf alloys [63]. Point defects have also been shown to stabilize martensite in Ni-Mn-Ga SMAs [64].…”

Section: Short-range Orderings and Their Effects On Martensite Stabilitysupporting

confidence: 70%

Computational Thermodynamics and Kinetics-Based ICME Framework for High-Temperature Shape Memory Alloys

Arróyave

Talapatra

Johnson

et al. 2015

Shap. Mem. Superelasticity

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Over the last decade, considerable interest in the development of High-Temperature Shape Memory Alloys (HTSMAs) for solid-state actuation has increased dramatically as key applications in the aerospace and automotive industry demand actuation temperatures well above those of conventional SMAs. Most of the research to date has focused on establishing the (forward) connections between chemistry, processing, (micro)structure, properties, and performance. Much less work has been dedicated to the development of frameworks capable of addressing the inverse problem of establishing necessary chemistry and processing schedules to achieve specific performance goals. Integrated Computational Materials Engineering (ICME) has emerged as a powerful framework to address this problem, although it has yet to be applied to the development of HTSMAs. In this paper, the contributions of computational thermodynamics and kinetics to ICME of HTSMAs are described. Some representative examples of the use of computational thermodynamics and kinetics to understand the phase stability and microstructural evolution in HTSMAs are discussed. Some very recent efforts at combining both to assist in the design of HTSMAs and limitations to the full implementation of ICME frameworks for HTSMA development are presented.

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Section: Short-range Orderings and Their Effects On Martensite Stabilitysupporting

confidence: 70%

Computational Thermodynamics and Kinetics-Based ICME Framework for High-Temperature Shape Memory Alloys

Arróyave

Talapatra

Johnson

et al. 2015

Shap. Mem. Superelasticity

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“…Other techniques such as rapid solidification also successfully produced melt spun ribbons with nanometre size grains. 152 However, martensite stabilisation and difficulty in achieving homogeneous distribution of alloying elements continue to pose tough challenges in rapidly solidified ribbons. 153 A very important outcome of the thin film studies on these alloy systems is that with a desirable microstructure, it is possible to obtain good shape memory behaviour in Ni-Ti-(Hf,Zr) HTSMAs.…”

Section: Iii1?2 Ni-ti-hf and Ni-ti-zrmentioning

confidence: 99%

High temperature shape memory alloys

Ma¹,

Караман²,

Noebe³

2010

International Materials Reviews

819

371

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Shape memory alloys (SMAs) with high transformation temperatures can enable simplifications and improvements in operating efficiency of many mechanical components designed to operate at temperatures above 100uC, potentially impacting the automotive, aerospace, manufacturing and energy exploration industries. A wide range of these SMAs exists and can be categorised in three groups based on their martensitic transformation temperatures: group I, transformation temperatures in the range of 100-400uC; group II, in the range of 400-700uC; and group III, above 700uC. In addition to the high transformation temperatures, potential high temperature shape memory alloys (HTSMAs) must also exhibit acceptable recoverable transformation strain levels, long term stability, resistance to plastic deformation and creep, and adequate environmental resistance. These criteria become increasingly more difficult to satisfy as their operating temperatures increase, due to greater involvement of thermally activated mechanisms in their thermomechanical responses. Moreover, poor workability, due to the ordered intermetallic structure of many HTSMA systems, and high material costs pose additional problems for the commercialisation of HTSMAs. In spite of these challenges, progress has been made through compositional control, alloying, and the application of various thermomechanical processing techniques to the point that several likely applications have been demonstrated in alloys such as Ti-Ni-Pd and Ti-Ni-Pt. In the present work, a comprehensive review of potential HTSMA systems are presented in terms of physical and thermomechanical properties, processing techniques, challenges and applications.

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“…To these alloys is added a third element (Ni-Ti-X) which, depending on the process and the amount added, may result in martensitic transformation temperatures starting above 100 ºC Karaca et al, 2013). Examples of these alloys are: Ti-Ni-Pd (Kockar et al, 2010), Ti-Ni-Pt (Kovarik et al, 2010), Ti-Ni-Ta (Gong et al, 2006), Ti-Ni-Au (Shi et al, 2014) and Ni-Ti-Hf (Manca et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

Effects of composition on transformation temperatures and microstructure of Ni-Ti-Hf shape memory alloys

Soares

Castro

2019

REM, Int. Eng. J.

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High transformation temperature shape-memory alloys (HTSMA) usually present a martensitic transformation temperature (Ms) starting at 100 ºC. That is the case of high nickel Ni-Ti-Hf alloys. This article presents experimental results obtained from arc melting of Ni 50 Ti 50-X Hf X .at% (X = 8, 11, 14, 17 and 20 .at%) alloys. This process homogenized every composition with similar relative crystallinity. Results confirm that transformation temperatures (TT) increase with increasing the amount of Hf. A martensitic matrix is formed by two metastable phases: R and B19'. From all the alloys studied, the B19' phase presented the highest percent fraction. Gradually adding Hf 3 .at% promoted a slow increase of crystalline fraction of R phase and a slow reduction of phase (Ti, Hf) 2 Ni, located at grain boundaries. Coherent/semi-coherent interface between (Ti, Hf) 2 Ni phase and the matrix may intensify the driving force for the formation of R phase, present on X-ray diffractograms.

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Ageing in Parent Phase and Martensite Stabilization in a Ni<SUB>50</SUB>Ti<SUB>30</SUB>Hf<SUB>20</SUB> Alloy

Cited by 7 publications

References 12 publications

Computational Thermodynamics and Kinetics-Based ICME Framework for High-Temperature Shape Memory Alloys

Computational Thermodynamics and Kinetics-Based ICME Framework for High-Temperature Shape Memory Alloys

High temperature shape memory alloys

Effects of composition on transformation temperatures and microstructure of Ni-Ti-Hf shape memory alloys

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