On the shape memory effect in internally faulted martensites

Otsuka, Kazuhiro; Wayman, C.M.

doi:10.1016/0036-9748(75)90271-9

Cited by 70 publications

(73 citation statements)

References 12 publications

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“…5, curve 2). This linear increase in critical stress values is attributed to the development of a stress-induced MT and is described by the Clausius-Clapeyron equation [12]. Temperature M d is taken to be the temperature at which critical stresses of martensite formation under loading are equal to the yield stress of the high-temperature phase, and at T > M d we observe plastic deformation of the B2-phase.…”

Section: Resultsmentioning

confidence: 99%

“…This implies that during evolution of a direct MT, a considerable amount of reversible energy is accumulated |ΔG rev |, which favors the development of a reverse MT under the conditions of counteracting chemical driving force, and there is very little energy dissipation during the evolution of reversible transitions. This relation of contributions from the reversible |ΔG rev | and dissipated |ΔG fr | energies into the non-chemical component of free energy during thermoeleastic MTs promotes phase-boundary mobility and high cyclic stability of the material during transformations [3,6,12]. Aging at 673 K for 1 h (transitional state to Group II) is accompanied by a sharp drop of MT temperatures, and a more than double increase in the temperature hysteresis Г (Table 1).…”

Section: In Heterophase Crystals the Presence Of Local Internal Stresmentioning

confidence: 97%

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Characteristic features of development of thermoelastic transformations in aged single crystals of a CoNiAl ferromagnetic alloy

et al. 2011

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Using Co 35 Ni 35 Al 30 (at. %) single crystals, the effect of temperature and duration of aging on the development of thermoelastic B2-L1 0 -martensitic transformations during heating/cooling is studied. It is found out that at room temperature these single crystals are in the В2-phase and contain a small volume fraction (about 2%) of the plastic γ-phase. In the aged single crystals, in the В2-matrix, Co-rich particles with hcp-and fcc-lattices and metastable Ni 2 Al particles precipitate, whose size is determined by the temperature and duration of aging. It is shown that aging gives rise decreased temperature of martensitic transformations. At the aging temperatures T ≥ 673 K there is a sharp increase in the temperature hysteresis and a total suppression of thermoelastic B2-L1 0 -martensitic transformations during heating/cooling and under loading. A thermodynamic description of the starting temperature of martensitic transformations M s as a function of microstructure of the aged single crystals particle size and interparticle spacing is proposed.

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Section: Resultsmentioning

confidence: 99%

Section: In Heterophase Crystals the Presence Of Local Internal Stresmentioning

confidence: 97%

Characteristic features of development of thermoelastic transformations in aged single crystals of a CoNiAl ferromagnetic alloy

et al. 2011

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“…Typically, shape memory alloy (SMA) is a kind of temperature-sensitive metallic functional materials, possessing shape memory effect (SME) and superelasticity (SE) characteristics, such as Ni-Ti and Cu-Al-Mn alloys12345. The SME and SE behaviors depend on the reversible martensitic transformation, having some differences between them.…”

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confidence: 99%

“…The SE property is associated with the stress-induced martensitic transformation in the austenite sample and the corresponding immediate reverse transformation upon unloading. Typically, a large stress-plateau upon loading could be observed for above two situations, owing to the reorientation of martensite variants and/or de-twinning for SME167, or the stress-induced martensitic transformation process for SE1689, respectively. Furthermore, the shape recovery process and the actuation speed reported in the existing SMAs usually takes place over a temperature range710111213, showing relatively low temperature-sensitivity.…”

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A jumping shape memory alloy under heat

Yang

Omori

Wang

et al. 2016

Sci Rep

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Shape memory alloys are typical temperature-sensitive metallic functional materials due to superelasticity and shape recovery characteristics. The conventional shape memory effect involves the formation and deformation of thermally induced martensite and its reverse transformation. The shape recovery process usually takes place over a temperature range, showing relatively low temperature-sensitivity. Here we report novel Cu-Al-Fe-Mn shape memory alloys. Their stress-strain and shape recovery behaviors are clearly different from the conventional shape memory alloys. In this study, although the Cu-12.2Al-4.3Fe-6.6Mn and Cu-12.9Al-3.8Fe-5.6Mn alloys possess predominantly L21 parent before deformation, the 2H martensite stress-induced from L21 parent could be retained after unloading. Furthermore, their shape recovery response is extremely temperature-sensitive, in which a giant residual strain of about 9% recovers instantly and completely during heating. At the same time, the phenomenon of the jumping of the sample occurs. It is originated from the instantaneous completion of the reverse transformation of the stabilized 2H martensite. This novel Cu-Al-Fe-Mn shape memory alloys have great potentials as new temperature-sensitive functional materials.

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“…При таком механизме превраще-ния в мартенсите возникают частичные дислокации, и не происхо-дит обратимое скольжение полных дислокаций с выходом их на по-верхность и образованием ступенек. Было предположено, что пла-стинка мартенсита окружена петлями частичных дислокаций пре-вращения, расположенных на каждой третьей базисной плоскости [135]. При обратном превращении петли стягиваются и полностью исчезают (аннигилируют).…”

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The Deformation Phenomena at Martensitic Transformations

Koval

Lobodyuk

2006

Usp. Fiz. Met.

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Рассмотрены и проанализированы такие необычные явления и свойства, обусловленные обратимыми мартенситными превращениями, как эффект памяти формы, сверхупругость и некоторые другие, а также такие опре-деляющие их параметры, как кристаллическая структура исходной и мартенситной фаз, морфология мартенситных кристаллов, их тонкая структура, механизмы перестройки при мартенситных превращениях в различных металлах и сплавах. Рассмотрены и обсуждены механизмы, обуславливающие восстановление исходной формы и состояния. Приве-дены наиболее характерные примеры практического использования этих необычных свойств.Розглянуто і проаналізовано такі незвичайні явища та властивості, спри-чинені оборотніми мартенситними перетвореннями, як ефект пам'яті фо-рми, надпружність та деякі інші, а також такі визначаючі їх параметри, як кристалічна структура початкової та мартенситної фаз, морфологія мартенситних кристалів, їхня тонка структура, механізми перебудови при мартенситних перетвореннях у ріжноманітних металах та стопах. Розглянуто та обговорено механізми, що обумовлюють відновлення вихі-дної форми та початкового стану. Приведено найбільш характерні прик-лади практичного використання таких незвичайних властивостей.Some unusual phenomena and properties caused by the reversible martensitic transformations such as the shape memory effect, superelasticity, etc. and such parameters as crystal structure of the parent and martensitic phases, morphology of the martensitic crystals, their fine structure, mechanisms of the reconstruction during austenite-martensite transformations are considered and analysed. The mechanisms, which cause a restoration of the initial form and state, are examined and discussed. The most typical examples of the practical applications of these unusual properties are given.Ключевые слова: структура, мартенситное превращение, перестройка, де-формация, межфазные границы, подвижность, обратимость, эффект памя- Fiz. Met. 2006, т. 7, сс. 53-116 Îòòèñêè äîñòóïíû íåïîñðåäñòâåííî îò èçäàòåëÿ Ôîòîêîïèðîâàíèå ðàçðåøåíî òîëüêî â ñîîòâåòñòâèè ñ ëèöåíçèåé 2006 ÈÌÔ (Èíñòèòóò ìåòàëëîôèçèêè èì. Ã. Â. Êóðäþìîâà ÍÀÍ Óêðàèíû) Íàïå÷àòàíî â Óêðàèíå.

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On the shape memory effect in internally faulted martensites

Cited by 70 publications

References 12 publications

Characteristic features of development of thermoelastic transformations in aged single crystals of a CoNiAl ferromagnetic alloy

Characteristic features of development of thermoelastic transformations in aged single crystals of a CoNiAl ferromagnetic alloy

A jumping shape memory alloy under heat

The Deformation Phenomena at Martensitic Transformations

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