Strong heating rate-dependent deterioration of shape memory effect in up/step quenched Cu-based alloys: A ductile Cu Al Mn alloy as an example

Yang, Qin; Wang, S.L.; Chen, J.; Zhou, Tiannan; Peng, Huabei; Yan, Wen

doi:10.1016/j.actamat.2016.04.004

Cited by 27 publications

(17 citation statements)

References 33 publications

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“…Some experiments have shown that the recoverability is strongly suppressed by decreasing heating rate, as reported for Cu-Zn-Al shape memory alloy [14,15]. It is found that the quenched Cu-based alloys could achieve ~90% shape recovery at high heating rate (~ 20 K/min), while only 10% is completed at a rate of 1 K/min.…”

Section: Comparison Of Simulation Results With Experimental Observationsmentioning

confidence: 66%

“…The recoverability of shape memory alloys could also be affected by quenched-in point defects. When the twinned copper-based alloys, such as Cu-Zn-Al [14] and Cu-Al-Mn [15], are subjected to upquenching, it is found that higher heating rates could promote the shape recovery (> 20 K/min). However, the recoverability is largely suppressed under low heating rates (~ 1 K/min) due to the strong pinning effect on slowly moving TBs by high concentration of mobile quenched-in vacancies.…”

Section: Introductionmentioning

confidence: 99%

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The interaction between vacancies and twin walls, junctions, and kinks, and their mechanical properties in ferroelastic materials

Ding

et al. 2019

Acta Materialia

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Vacancies strongly interact with twin boundaries and often change dramatically the properties of a ferroelastic material. However, the understanding of this behavior at an atomic-level is still deficient. Here we study vacancy diffusion processes across very large length-and time-scales using a combination of molecular dynamics and Monte Carlo simulations. We find that vacancies reduce their energy by residing at twin boundaries, kinks inside domain boundaries, and junctions between domain boundaries. Vacancies have the largest binding energy inside junctions and co-migrate with the motion of the junctions. For the weaker trapping inside twin boundaries, a "ghost line" may be generated because vacancies do not necessarily diffuse with moving boundaries and are left behind, leaving a trace of a previous position of the domain boundary. Needle twins act as channels for fast diffusion with almost one order of magnitude higher vacancy diffusivity than in bulk. The relative concentration of vacancies at twin boundaries (ρVa) is a function of the average vacancy concentration (CVa) with ρVa ~ CVa α and α = 0.61, in contrast to that of immobile vacancies case with α = 0.4. The concentration of vacancies at twin boundaries is enriched ca. 5 times at low temperatures. With increasing temperature, the enrichment drops as the trapping potential at the twin boundaries decreases (thermal release). The distribution of energydrop upon twin pattern evolution follows a power law. The exponent ε increases from ~1.44 to 2.0 when the vacancy concentration increases. The power law exponent is the same in the athermal region, while Vogel-Fulcher behavior is found at high temperatures.

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Section: Comparison Of Simulation Results With Experimental Observationsmentioning

confidence: 66%

Section: Introductionmentioning

confidence: 99%

The interaction between vacancies and twin walls, junctions, and kinks, and their mechanical properties in ferroelastic materials

Ding

et al. 2019

Acta Materialia

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“…The two factors can efficiently promote the increase of IF. [ 50,51 ] This phenomenon is different from the response of high‐temperature IF to the change of the quantity of vacancies. Vacancies are movable at high temperatures and have interactions with dislocations and cause extra energy dissipation; thus, the high‐temperature IF decreases after thermal treatment due to the reduction of dislocations and vacancies.…”

Section: Resultsmentioning

confidence: 97%

Strain Amplitude Dependence of Internal Friction in a Cu–Al–Mn Shape Memory Alloy

Jiao

Yin

Zhang

et al. 2022

Physica Status Solidi (a)

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Strain amplitude (SA) dependence of internal friction (IF) in a Cu–Al–Mn shape memory alloy (SMA) is investigated. Microstructure observation is conducted with the aim to clarify related mechanisms. It is found that the IF measured during the continuous heating process shows a nonmonotonous dependence on SA, that is, the IF increases first and then decreases. The increase of IF can be attributed to the mergence of martensite laths promoted by the reorientation of martensite variants, whereas the decrease of IF is related to the decrease in the density of moveable interfaces. The isothermal IF measured at low temperatures increases monotonously with the increase in SA, because the density of movable interfaces and the sliding distance of these interfaces in the tangential direction increase. Thermal cycles can significantly improve the isothermal IF because of the annihilation of quenched‐in vacancies and the reorientation of martensite variants. At around 240 °C, the isothermal IF in all specimens shows a nonmonotonous dependence on SA, which can be ascribed to the dragging effect of quenched‐in vacancies on dislocations and the breakaway of dislocations from these vacancies when the SA is high enough.

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“…The most effective and widely used shape memory alloys are nitinol [3,[7][8][9][10][11][12], copper based shape memory alloys [13][14][15], and iron based shape memory alloys [16][17][18]. Applications of shape memory alloys depend upon their phase transformation temperatures.…”

Section: Transformation Temperatures and Their Importancementioning

confidence: 99%

“…Transformation temperatures of nitinol are well below or close to body temperature, which is why nitinol has a large number of applications as a biomaterial [19][20][21] compared to copper based and iron based shape memory alloys where transformation temperatures are well above the body temperature [13][14][15][16][17][18]. Copper based shape memory alloys are suitable for high temperature, ∼473 K, applications; however, due to above-body-temperature transformation temperatures, these alloys are not suitable as a biomaterial [13][14][15]. There is a need for research on copper based shape memory alloys to decrease their transformation temperatures below body temperature so that these alloys can be used as a biomaterial.…”

Section: Transformation Temperatures and Their Importancementioning

confidence: 99%

Brief Overview on Nitinol as Biomaterial

Wadood

2016

Advances in Materials Science and Engineering

111

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Shape memory alloys remember their shape due to thermoelastic martensitic phase transformation. These alloys have advantages in terms of large recoverable strain and these alloys can exert continuous force during use. Equiatomic NiTi, also known as nitinol, has a great potential for use as a biomaterial as compared to other conventional materials due to its shape memory and superelastic properties. In this paper, an overview of recent research and development related to NiTi based shape memory alloys is presented. Applications and uses of NiTi based shape memory alloys as biomaterials are discussed. Biocompatibility issues of nitinol and researchers’ approach to overcome this problem are also briefly discussed.

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Strong heating rate-dependent deterioration of shape memory effect in up/step quenched Cu-based alloys: A ductile Cu Al Mn alloy as an example

Cited by 27 publications

References 33 publications

The interaction between vacancies and twin walls, junctions, and kinks, and their mechanical properties in ferroelastic materials

The interaction between vacancies and twin walls, junctions, and kinks, and their mechanical properties in ferroelastic materials

Strain Amplitude Dependence of Internal Friction in a Cu–Al–Mn Shape Memory Alloy

Brief Overview on Nitinol as Biomaterial

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