High‐Temperature Shape Memory Effect in Ti‐Ta Thin Films Sputter Deposited at Room Temperature

Motemani, Yahya; Buenconsejo, Pio John S.; Crăciunescu, Corneliu Marius; Ludwig, Alfred

doi:10.1002/admi.201400019

Cited by 23 publications

(20 citation statements)

References 28 publications

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“…All Bragg reflections were indexed as orthorhombic α″ martensite, space group Cmcm . The possible mechanisms for the formation of martensite in Ti–Ta thin films deposited at room temperature were reported previously . Lattice parameters of the α″ martensite as well as the microstructural information in the as‐deposited film were obtained following a Le Bail pattern fitting procedure of two‐dimensional synchrotron data (Figure b and c).…”

Section: Resultsmentioning

confidence: 98%

“…As an example, it has been reported that the addition of up to 3 at% Al (or Sn) to Ti 70 Ta 30 can suppress the ω phase formation and thus improve the functional stability . Ti–Ta alloys have so far been mainly studied as bulk materials, their fabrication as thin films was rarely reported . In thin‐film form, they can be used as high‐temperature micro‐actuators in micro‐electro‐mechanical systems (MEMS).…”

Section: Introductionmentioning

confidence: 99%

“…In thin‐film form, they can be used as high‐temperature micro‐actuators in micro‐electro‐mechanical systems (MEMS). Recently, the formation of disordered α″ martensite in Ti 70 Ta 30 , Ti 68 Ta 32 , and Ti 67 Ta 33 thin films deposited at room temperature by magnetron sputtering was reported . The room‐temperature fabrication of Ti–Ta HTSMA thin films is of importance for MEMS, where post‐annealing processes are generally not desirable.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, the as‐deposited Ti 70 Ta 30 film showed a reversible martensitic transformation and a high‐temperature shape memory effect. In this study the shape memory effect was qualitatively confirmed through bending/heating experiments performed with a cantilever‐shaped free‐standing film during heating . However for practical SMA applications, the functional or actuation properties have to be characterized more precisely.…”

Section: Introductionmentioning

confidence: 99%

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Microstructure, Shape Memory Effect and Functional Stability of Ti₆₇Ta₃₃ Thin Films

et al. 2015

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Ti-Ta based alloys are an interesting class of high-temperature shape memory materials. When fabricated as thin films, they can be used as high-temperature micro-actuators with operation temperatures exceeding 100°C. In this study, microstructure, shape memory effect and thermal cycling stability of room-temperature sputter deposited Ti 67 Ta 33 thin films are investigated. A disordered a 00 martensite (orthorhombic) phase is formed in the as-deposited Ti 67 Ta 33 films. The films show a columnar morphology with the columns being oriented perpendicular to the substrate surface. They are approximately 200 nm in width. XRD texture analysis reveals a martensite fiber texture with {120} and {102} fiber axes. The XRD results are confirmed by TEM analysis, which also shows columnar grains with long axes perpendicular to the {120} and {102} planes of a 00 martensite. The shape memory effect is analyzed in the temperature range of -10 to 240°C using the cantilever deflection method, with special emphasis placed on cyclic stability. Ti 67 Ta 33 thin films undergo a forward martensitic transformation at M s % 165°C, with a stress relaxation of approximately 33 MPa during the transformation. The actuation response of the film actuators degrades significantly during thermal cycling. TEM analysis shows that this degradation is related to the formation of nanoscale v precipitates (5-13 nm) which form above the austenite finish temperature. These precipitates suppress the martensitic transformation, as they act as obstacles for the growth of martensite variants.

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Section: Resultsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Microstructure, Shape Memory Effect and Functional Stability of Ti₆₇Ta₃₃ Thin Films

et al. 2015

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“…The martensitic phases also lead to other exotic properties, such as shape memory effects . This memory effect was investigated by Motemani et al in Ti‐Ta coatings produced by magnetron sputtering. Montemani et al results indicated that by using magnetron co‐sputtering, it was possible to obtain the α″ martensitic phase in the as‐deposited room temperature films for Ta contents between 30 and 33 at%.…”

Section: Introductionmentioning

confidence: 99%

Compositional and Tribo‐Mechanical Characterization of Ti‐Ta Coatings Prepared by Confocal Dual Magnetron Co‐Sputtering

et al. 2017

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Titanium-Tantalum coatings are deposited by magnetron co-sputtering technique, using independently driven titanium and tantalum targets. The effect of the Ta content on the structure, mechanical, and wear properties of Ti films is investigated. It is found that the percentage of the added Ta varies linearly from 3.7 to 31.3 at% by increasing the power applied to the Ta target from 10 to 100 W. The XRD results show that the coatings are crystalline, and there is no evidence of the formation of intermetallic phases, instead formation of metastable phases of α 00 and β depending on Ta content are observed, though the samples are deposited at low temperature (150 C). It is shown that the elastic strain to failure (H/E r ; hardness to reduced elastic moduli ratio) can be increased by 40% through the formation of crystalline phases with a lower E, while the hardness remains constant. The tribological study shows that increasing the Ta content up to 14.9 at% causes a significant improvement in adhesion of the coating to a soft metallic substrate.

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Evaluations of Mechanical Properties and Functionalities of the Al- and Zr-Tailored Ti–5.5Mo Shape Memory Alloys for Biomedical Applications

Chiu,

Hayakawa,

Nohira

et al. 2024

Metall Mater Trans A

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Due to the critical world population aging issue, biomaterials are important topics in the biomedical community. Among the biomedical materials, shape memory alloys (SMAs) are considered to be promising materials owing to their functionalities, such as shape memory effect (SME) and superelasticity (SE). Ti–Mo–Al-based alloys, which are biocompatible materials, are basic materials in the Ti-based SMAs due to the evaluation of the phase stability through the calculations of Mo and Al equivalents. This study, in addition, introduced Zr into the Ti–Mo–Al-based alloys for its highly biocompatibility and being a fine modifier to tune the phase stability. The mechanical (i.e., strength and elongation) and functional (i.e., SME and SE) properties have been investigated in this study to reveal the practicability of the biomedical applications for human usage. It was found that addition of Zr to the Ti–Mo alloy shows slight influence on the mechanical properties of the binary Ti–Mo alloy. With the addition of Al, that is, ternary Ti–Mo–Al alloys, two-stage yielding was found in the tensile examinations. Among all the alloys, the Ti–5.5Mo–4Al, the Ti–5.5Mo–4Al–6Zr, and the Ti–5.5Mo–8Al–6Zr (mol pct) alloys performed excellent shape recovery of about 100 pct in the bending and heating tests. Especially, the Ti–5.5Mo–4Al–6Zr and the Ti–5.5Mo–8Al–6Zr alloys further show high strength. Results in this study could be a guideline for the design of the fundamental Ti–Mo–Al-based SMAs.

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High‐Temperature Shape Memory Effect in Ti‐Ta Thin Films Sputter Deposited at Room Temperature

Cited by 23 publications

References 28 publications

Microstructure, Shape Memory Effect and Functional Stability of Ti₆₇Ta₃₃ Thin Films

Microstructure, Shape Memory Effect and Functional Stability of Ti₆₇Ta₃₃ Thin Films

Compositional and Tribo‐Mechanical Characterization of Ti‐Ta Coatings Prepared by Confocal Dual Magnetron Co‐Sputtering

Evaluations of Mechanical Properties and Functionalities of the Al- and Zr-Tailored Ti–5.5Mo Shape Memory Alloys for Biomedical Applications

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High‐Temperature Shape Memory Effect in Ti‐Ta Thin Films Sputter Deposited at Room Temperature

Cited by 23 publications

References 28 publications

Microstructure, Shape Memory Effect and Functional Stability of Ti67Ta33 Thin Films

Microstructure, Shape Memory Effect and Functional Stability of Ti67Ta33 Thin Films

Compositional and Tribo‐Mechanical Characterization of Ti‐Ta Coatings Prepared by Confocal Dual Magnetron Co‐Sputtering

Evaluations of Mechanical Properties and Functionalities of the Al- and Zr-Tailored Ti–5.5Mo Shape Memory Alloys for Biomedical Applications

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Microstructure, Shape Memory Effect and Functional Stability of Ti₆₇Ta₃₃ Thin Films

Microstructure, Shape Memory Effect and Functional Stability of Ti₆₇Ta₃₃ Thin Films