Fatigue of LIGA Ni Micro-Electro-Mechanical System Thin Films

Yang, Yong; Allameh, Seyed M.; Lou, Jun; Imasogie, B. I.; Boyce, Brad Lee; Soboyejo, W. O.

doi:10.1007/s11661-007-9246-y

Cited by 10 publications

(12 citation statements)

References 38 publications

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“…Stress-or strain-driven recrystallization and grain growth has also been observed in UFG Cu under low-cycle cyclic plasticity conditions, and has been associated with observed cyclic softening behavior [136]. Yang et al have also reported recrystallization at the tip of a propagating fatigue crack in CG electrodeposited Ni [122]. In our own work on the fatigue-crack initiation and growth behavior of NC Ni-Mn, we have found localized regions of grain growth during fatigue loading, as shown in Fig.…”

Section: Fatigue-induced Grain Growthmentioning

confidence: 92%

“…5, the fatigue crack growth threshold in NC metals (∆K th~2 -4 MPa√m at R = 0.1) is below typical levels for long-crack behavior [14,20,23]. Data for larger grained metals [122,148], alumina ceramic [165], and a bulk metallic glass [166] are shown for comparison in CG metals (typically ∆K th~4 -10 MPa√m at R = 0.1). Here again, this may be attributable to potentially reduced effects of crack closure or crack-tip shielding in NC metals.…”

Section: Experimental Datamentioning

confidence: 99%

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A Review of Fatigue Behavior in Nanocrystalline Metals

2009

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Nanocrystalline metals have been shown to exhibit unique mechanical behavior, including break-down in Hall-Petch behavior, suppression of dislocation-mediated plasticity, induction of grain boundary sliding, and induction of mechanical grain coarsening. Early research on the fatigue behavior of nanocrystalline metals shows evidence of improved fatigue resistance compared to traditional microcrystalline metals. In this review, experimental and modeling observations are used to evaluate aspects of cyclic plasticity, microstructural stability, crack initiation processes, and crack propagation processes. In cyclic plasticity studies to date, nanocrystalline metals have exhibited strongly rate-dependent cyclic hardening, suggesting the importance of diffusive deformation mechanisms such as grain-boundary sliding. The cyclic deformation processes have also been shown to cause substantial mechanicallyinduced grain coarsening reminiscent of coarsening observed during large-strain monotonic deformation of nanocrystalline metals. The crack-initiation process in nanocrystalline metals has been associated with both subsurface internal defects and surface extrusions, although it is unclear how these extrusions form when the grain size is below the scale necessary for persistent slip band formation. Finally, as expected, nanocrystalline metals have very little resistance to crack propagation due to limited plasticity and the lack of crack path tortuosity among other factors. Nevertheless, like bulk metallic glasses, nanocrystalline metals exhibit both ductile fatigue striations and metal-like Paris-law behavior. The review provides both a comprehensive critical survey of existing literature and a summary of key areas for further investigation.

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Section: Fatigue-induced Grain Growthmentioning

confidence: 92%

Section: Experimental Datamentioning

confidence: 99%

A Review of Fatigue Behavior in Nanocrystalline Metals

2009

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“…This softening leads to a decrease in the stress amplitude and hence the slope of the stress-strain hysteresis is reduced. This decrease could be compensated, as it is in the work of Yang et al, by changing the position of the piezo actuator to maintain mean load [25,26]. Nevertheless this is not the case in this manuscript.…”

Section: Comparison Of Crack Initiation Detection Methodsmentioning

confidence: 79%

Small-Scale Multiaxial Setup for Damage Detection Into the Very High Cycle Fatigue Regime

et al. 2015

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Micro electro mechanical systems, coatings, and thin films contain materials that are often subjected to complex loading conditions and high frequencies. Therefore, the implementation of a resonant multiaxial fatigue setup for small-scale samples is of high interest. Finite Element simulations have been used to design small-scale samples which possess very close bending and torsional resonant frequencies.The bending and torsional modes are excited by two piezo actuators working either in or out of phase with one another. The bending and torsional amplitudes are measured independently by a laser and the actuator amplitudes are controlled by a Field Programmable Gate Array. The fatigue setup can be used with a varying range of sample sizes from centimeters down to tens of micrometers. The novel multiaxial resonant micro fatigue setup as well as results (fatigue damage for Ni and lifetime for Cu) from bending small-scale fatigue tests are shown and discussed.

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“…Since such devices are likely to undergo monotonic and cyclic loads that can induce sub-critical crack growth, there have been a number of studies of the tensile properties [6][7][8][9] and fatigue and fracture behavior [10][11][12][13][14][15][16] of LIGA Ni MEMS thin films. However, there have been relatively few studies of the mechanisms of fatigue crack nucleation in LIGA Ni MEMS thin films [12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

“…However, there have been relatively few studies of the mechanisms of fatigue crack nucleation in LIGA Ni MEMS thin films [12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%