Thermoelasticity, pseudoelasticity and the memory effects associated with martensitic transformations

Warlimont, Hans; Delaey, L.; Krishnan, RV; Tas, H.

doi:10.1007/bf00552941

Cited by 153 publications

(85 citation statements)

References 27 publications

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“…The amorphous thin films can be crystallized by heating up to 500 C [94]. There was no transformation occurring between -50 C and 250 C. It was found that the phase transition temperatures shift with the change in Ni content [92] and the start temperature of martensitic transformation (M S ) decreases rapidly with an increase in the Ni content [94]. Therefore, the transformation temperature falls out of the scanning range.…”

Section: X-ray Analysis Of the Crystallized Thin Filmmentioning

confidence: 99%

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Cavitation erosion resistance of NiTi thin films produced by Filtered Arc Deposition

Yang

Tieu

Dunne

et al. 2009

Wear

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AcknowledgementsFirst and foremost, I would like to thank my principal supervisor, Professor A. Kiet.Tieu., for providing timely and insightful advice, financial and spiritual support. My supervisor's implicit trust in my research abilities not only allowed me to freely pursue my goals, but also gave me an opportunity to learn how to manage time and allocate resources. Special thanks go to Professor Druce Dunne, for his insightful instruction and for all the generous attention and time he devoted to my research work. Tables Table 5. List of List of Figures AbstractThe objective of this work was to produce near-equiatomic NiTi thin films by filtered arc deposition system (FADS) to improve the cavitation erosion resistance of a steel base working in liquid. First, deposition conditions were optimized in order to obtain near-equiatomic NiTi films. Energy dispersive spectroscopy (EDS) was used to measure the composition of films. It was found that both the substrate bias voltage and arc current affect the compositions of as-deposited NiTi films. X-ray diffractometry (XRD) and transmission electron microscopy (TEM) were used to investigate the microstructures of Ni-rich, Ti-rich and near-equiatomic films. Their thermal behaviours were tested using differential scanning calorimetry (DSC). Atomic force microscopy (AFM), ultra micro-indentation system (UMIS) and Romulus scratch testing were used to measure the roughness, hardness and adhesive force of a near-equiatomic thin film.The cavitation erosion resistance of the near-equiatomic NiTi film was assessed using ASTM Test Method G32. It was found that NiTi thin films showed significantly higher cavitation erosion resistance than 316 austenitic stainless steel. The improved cavitation erosion resistance was attributed to the recoverable deformation associated with pseudoelasticity of the NiTi thin film.The effect of substrate temperature on the properties of NiTi thin films was investigated by preheating substrates to different temperatures (130 C, 300 C, 430 C and 600 C). temperature of 600 C was more resistant to cavitation erosion than films deposited at other bias voltages with a similar substrate temperature.The effect of substrate material on the properties of NiTi thin films was investigated by comparing films on mild steel and on austenitic stainless steel. For similar deposition conditions, the NiTi film deposited on mild steel consisted of B2, B19' and R phases, while the NiTi film on stainless steel was dominated by B2 parent phase. This is probably because the lower thermal conductivity of austenitic stainless steel resulted in a higher deposition temperature.The dominance of the B2 phase for deposition with a high substrate temperature, a high bias voltage and the use of stainless steel substrate was not found to be due to Ni-enrichment of the films, but is consistent with stabilization of the parent phase by possible pick-up oxygen and nitrogen from the chamber atmosphere when the deposition temperature is high.The research program successfully pro...

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Section: X-ray Analysis Of the Crystallized Thin Filmmentioning

confidence: 99%

“…The high thermoelastic reversibility makes equiatomic NiTi thin film suitable for actuation control in MEMS [94]. …”

Section: X-ray Analysis Of the Crystallized Thin Filmmentioning

confidence: 99%

Cavitation erosion resistance of NiTi thin films produced by Filtered Arc Deposition

Yang

Tieu

Dunne

et al. 2009

Wear

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“…He then goes on to a consideration of the electronic basis for the p phase stability suggested by Fuchs [4] and Mott and Jones [5]. It is clearly an old problem and an especially interesting one since the martensitic transformation temperature in most alloy systems is a precipitously dramatic function of chemical (electron) concentration [6].…”

Section: Neutron Studies Of Pretransitional Fluctuations Above Structmentioning

confidence: 99%

Neutron Studies of Pretransitional Fluctuations Above Structural Transitions in Metals

Moss

1977

J. Phys. Colloques

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Resume. -Les transitions de phase structurales dans les metaux 3-d mettent en jeu des transformations simples (de Burgers) entre les structures bien connues, cfc, cc, hc, et la phase mktastable omiga. Ces changements cristallographiques sont accompagnks de cisaillements macroscopiques variks et de deplacements microscopiques dependant du type de changements de symktrie mis en jeu. La plupart de ces transitions sont du ler ordre, cependant, et l'on continue de chercher jusqu'8 quel point on peut decrire de tels changements de phase sur la base d'une dynamique de rbseau. La diffraction de neutron, associke aux etudes de rayons X, est en principe l'outil ideal pour attaquer ce problkme, et on a mis en evidence dans certains de ces systemes, l'existence de mode mou etlou de fluctuations prktransitionnelles. Cependant, la majoritk de ces systkmes ne prksentent pas de comportement de mode mou dramatique, comme il se manifeste, par exemple, dans Nb3Sn, et dans de nombreux cas, la rkponse dynamique de r6seau apparait normale. I1 est fait aussi brikvement allusion 8 I'influence des defauts sur la diffusion des neutrons.Abstract. -Structural phase transitions in (3-D) metals usually involve simple (Burgers) transformations among the well known structures, fcc, bcc, hcp and metastably, the omega phase. Accompanying these crystallographic changes are various macroscopic shears and microscopic shuffles depending upon what kinds of symmetry changes are ultimately involved. Most of the transitions are first order, however, and it has been of continuing interest to explore the extent to which a lattice dynamical basis can be given to such phase changes. Neutron scattering, coupled with X-ray studies, is in principle an ideal tool for looking at this problem and limited evidence exists for mode softening and/or pretransitional fluctuations in some of these systems. The majority of systems do not, however, exhibit dramatic soft mode behavior, as is seen, for example, in Nb3Sn, and in many cases the lattice dynamical response appears normal. The influence of defects on the neutron scattering is also briefly alluded to.

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“…In CuAlNi alloys subjected to stress-free cooling, the D0 3 ordered parent phase ( 1 austenite) transforms into orthorhombic 2H ( 1 1 on the alloy composition [1]. In the presence of an external stress, multistage thermoelastic behavior is observed reflecting variety of successive austenite-to-martensite and martensite-to-martensite transitions [2][3][4][5][6].…”

Section: Introductionmentioning

confidence: 99%

“…In the presence of an external stress, multistage thermoelastic behavior is observed reflecting variety of successive austenite-to-martensite and martensite-to-martensite transitions [2][3][4][5][6]. Beside 1 and 1 martensites, also 1 structure was reported in CuAlNi single crystals subjected to tensile stress in the [100] 1 direction [4,6]. In-situ light microscopy and X-ray diffraction were utilized to follow the morphological changes associated with successive martensitic transformations under stress and the resulting crystal structures [2][3][4].…”

Section: Introductionmentioning

confidence: 99%

In-situTEM study of stress-induced transformations in CuAlNi

Zárubová

Gemperlová

Gemperle

et al. 2009

ESOMAT 2009 - 8th European Symposium on Martensitic Transformations

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Abstract. Stress-induced martensitic transformations and twinning processes were studied in thin foils of CuAlNi single crystals strained in-situ in a transmission electron microscope. A detailed structure analysis comprised identification of phases existing under stress and determination of their mutual crystallographic orientation. Three transformation processes were detected: i) transformation of austenite into 2H martensite at low stress levels; ii) twinning/detwinning processes in 2H martensite, and iii) transformation between austenite and 18R martensite at higher stress levels. Nucleation and growth of martensite plates were followed, and morphology of the austenite/martensite habit planes was examined. Existence of planar interfaces between a single variant of 2H martensite and austenite on microscopic level was proved.

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Thermoelasticity, pseudoelasticity and the memory effects associated with martensitic transformations

Cited by 153 publications

References 27 publications

Cavitation erosion resistance of NiTi thin films produced by Filtered Arc Deposition

Cavitation erosion resistance of NiTi thin films produced by Filtered Arc Deposition

Neutron Studies of Pretransitional Fluctuations Above Structural Transitions in Metals

In-situTEM study of stress-induced transformations in CuAlNi

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