Thin-film processing of TiNi shape memory alloy

Walker, James Alfred; Gabriel, K.J.; Mehregany, Mehran

doi:10.1016/0924-4247(90)85047-8

Cited by 171 publications

(51 citation statements)

References 9 publications

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“…However, they did not observe the martensitic transformation, because they did not hit near equiatomic composition. In 1990 many papers appeared on Ti-Ni thin films made by sputter deposition, which is a convenient method for fabricating MEMS [354][355][356][357][358][359][360]. Among these Walker et al [354] and Busch et al [355] recognized the importance of crystallization process to realize martensitic transformations, and observed shape memory effect.…”

Section: Thin Films: Process Via Amorphous Statementioning

confidence: 99%

Physical metallurgy of Ti–Ni-based shape memory alloys

Otsuka

Ren

2005

Progress in Materials Science

3,832

2,030

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Section: Thin Films: Process Via Amorphous Statementioning

confidence: 99%

Physical metallurgy of Ti–Ni-based shape memory alloys

Otsuka

Ren

2005

Progress in Materials Science

3,832

2,030

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“…For thin films, 3,4,5,6 nanowires, 7,8 and nanocrystals 9,10 the geometric constraints will have an impact on martensite formation. Recently, Frick et al 11 experimentally studied the stress-strain behavior of nanopillars of nickel titanium shape-memory alloys (SMA), using nanoindentation tests.…”

Section: Introductionmentioning

confidence: 99%

Microstructure and mechanical properties of constrained shape-memory alloy nanograins and nanowires

Bouville¹,

Ahluwalia²

2008

Acta Materialia

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We use the phase-field method to study the martensitic transformation at the nanoscale. For nanosystems such as nanowires and nanograins embedded in a stiff matrix, the geometric constraints and boundary conditions have an impact on martensite formation, leading to new microstructuressuch as dots aligned on a square lattice with axes along 01 -or preventing martensite formation altogether. We also perform tension tests on the nanowires. The stress-strain curves are very different from bulk results. Moreover, they are weakly affected by microstructures -the mechanical response of nanowires with different microstructures may be similar, while nanowires with the same microstructure may have a different mechanical behavior. We also observe that at the transition temperature, or slightly below it, the narrowest wires behave pseudoelastically whereas wider wires are in the memory-shape regime. Moreover the yield stress does not change monotonically with width: it has a minimum value at intermediate width.

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“…They have been studied extensively over the last fifty years with most attention focused on bulk materials. Recently, the shape memory effect has been demonstrated in thin films of these alloys [1][2][3][4][5][6][7], making them attractive candidates for use as actuators in microelectromechanical systems (MEMS). It is, however, difficult to induce an intrinsic two-way shape memory effect in thin films and a biasing spring is generally needed to restore the initial state after actuation.…”

Section: Introductionmentioning

confidence: 99%

Laser annealing of amorphous NiTi shape memory alloy thin films to locally induce shape memory properties

2005

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We present the results of a crystallization study on NiTi shape memory thin films in which amorphous films are annealed by a scanning laser. This technique has the advantage that shape memory properties can be spatially distributed as required by the application. A kinetics study shows that nucleation of the crystalline phase occurs homogenously in the films. Consequently, the laser annealing process produces polycrystalline films with a random crystallographic texture.The crystallized films have a uniform microstructure across the annealed areas. The material in the crystalline regions transforms reversibly to martensite on cooling from elevated temperature and stress measurements show that a significant recovery stress is achieved in the films upon transformation.

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Thin-film processing of TiNi shape memory alloy

Cited by 171 publications

References 9 publications

Physical metallurgy of Ti–Ni-based shape memory alloys

Physical metallurgy of Ti–Ni-based shape memory alloys

Microstructure and mechanical properties of constrained shape-memory alloy nanograins and nanowires

Laser annealing of amorphous NiTi shape memory alloy thin films to locally induce shape memory properties

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