Fracture Behavior of Micro-Sized Ni-P Amorphous Alloy Specimens

Ichikawa, Y.; Maekawa, S.; Takashima, Kazuki; Shimojo, M.; Higo, Yakichi; Swain, Michael V.

doi:10.1557/proc-605-273

Cited by 12 publications

(17 citation statements)

References 3 publications

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“…Once the method was perfected, these often gave data consistent with data from macroscopic tests of the same material (Si notably) [2,13,19,[37][38][39][40]. Finally, some authors have used fatigue of notched microspecimens to create precracks in metallic specimens (prone to largescale yielding, however) [41][42][43], and also in silicon [44].…”

Section: Introductionmentioning

confidence: 74%

Fracture toughness testing of nanocrystalline alumina and fused quartz using chevron-notched microbeams

et al. 2015

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We show that chevron-notched samples offer an attractive approach to the measurement of fracture toughness in micron-scale samples of brittle materials and use the method to characterize quartz and nanocrystalline alumina. Focused ion beam milling is used to carve bend bars of rectangular cross-section a few micrometres wide and containing a notch with a triangular ligament. Load-controlled testing is conducted using a nanoindentation apparatus. If the notch is appropriately machined, cracks nucleate and propagate in a stable fashion before becoming unstable. Sample dimensions are measured using a scanning electron microscope, and are used as input in finite element simulations of the bars' elastic deformation for various crack lengths. The calculated compliance calibration curve and the measured peak load then give the local fracture toughness of the material. Advantages of the method include a low sensitivity to environmental subcritical crack growth, and the fact that it measures toughness at the tip of a sharp crack situated in material unaffected by ion-milling. The approach is demonstrated on two materials, namely, monolithic fused quartz and nanocrystalline alumina Nextele 610 fibres; results for the latter give the intrinsic grain boundary toughness of alumina, free of grain bridging effects.

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Section: Introductionmentioning

confidence: 74%

Fracture toughness testing of nanocrystalline alumina and fused quartz using chevron-notched microbeams

et al. 2015

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“…Notches of depth 6 μm ( a / W = 0.5) were introduced into samples for fracture toughness testing by FIB machining. Previous research has demonstrated that the introduction of fatigue pre‐crack is necessary for reliable results in micro‐sized specimens 16 . However, it is extremely difficult to introduce a fatigue pre‐crack into the micro‐sized specimens by bending fatigue.…”

Section: Methodsmentioning

confidence: 99%

“…A mechanical testing machine that can apply both static and cyclic loads to micro‐sized specimens has been developed, 15 and the effects of specimen size on fatigue and fracture investigated. This was completed using Ni–P amorphous alloy, micro‐sized cantilever beam specimens approximately 1/1000th the size of ordinary‐sized specimens 16–21 . This material has hardly any intrinsic defects and has been used as hard‐disk substrates.…”

Section: Introductionmentioning

confidence: 99%

Fatigue and fracture of a Ni–P amorphous alloy thin film on the micrometer scale

Takashima

Higo

2005

Fatigue Fract Eng Mat Struct

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A B S T R A C T Fracture and fatigue tests have been performed on micro-sized specimens for microelectromechanical systems (MEMS) or micro system technology (MST) applications. Cantilever beam type specimens with dimensions of 10 × 12 × 50 µm 3 , approximately 1/1000th the size of ordinary-sized specimens, were prepared from a Ni-P amorphous thin film by focused ion beam machining. Fatigue crack growth and fracture toughness tests were carried out in air at room temperature, using a mechanical testing machine developed for micro-sized specimens. In fracture toughness tests, fatigue pre-cracks were introduced ahead of the notches. Fatigue crack growth resistance curves were obtained from the measurement of striation spacing on the fatigue surface, with closure effects on the fatigue crack growth also being observed for micro-sized specimens. Once fatigue crack growth occurs, the specimens fail within one thousand cycles. This indicates that the fatigue life of micro-sized specimens is mainly dominated by a crack initiation process, also suggesting that even a micro-sized surface flaw may be an initiation site for fatigue cracks which will shorten the fatigue life of micro-sized specimens. As a result of fracture toughness tests, the values of plane strain fracture toughness, K IC , were not obtained because the criteria of plane strain were not satisfied by this specimen size. As the plane strain requirements are determined by the stress intensity, K , and by the yield stress of the material, it is difficult for micro-sized specimens to satisfy these requirements. Plane-stressand plane-strain-dominated regions were clearly observed on the fracture surfaces and their sizes were consistent with those estimated by fracture mechanics calculations. This indicates that fracture mechanics is still valid for such micro-sized specimens. The results obtained in this investigation should be considered when designing actual MEMS/MST devices.

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“…Microsized cantilevers were introduced into this material using a Focussed Ion Beam (FIB). This equipment follows the MFT-2000 machine previously developed for microsized material testing [4,6,8]. Four "A" type samples (~ 10 x 20 x 40µm) were tested, followed by one "B" type sample (~15 x 30 x 80µm).…”

Section: Methodsmentioning

confidence: 99%

“…The success of MEMS as accelerometers controlling the deployment of automotive airbags as well as in ink jet printing have effectively demonstrated their potential for use in innovative functions. As MEMS devices require microsized material, plane strain criteria [3] are unachievable in many cases [4][5][6]. These benefits are of particular interest to developers of aerospace programs, where significant reductions in size and weight can be expected to lead to cascading cost benefits, through reduced production expense and greater fuel efficiency.…”

Section: Introductionmentioning

confidence: 99%

Fatigue Testing of microsized samples of γ-TiAl based material

2004

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High strength γ-TiAl based alloys, such as Ti-46Al-5Nb-1W (Alloy 7), which were originally developed for gas turbine and automotive applications are now being considered for application in Micro Electro Mechanical Systems (MEMS). This requires the evaluation of these materials upon the microscale. As international standards do not currently exist for the evaluation of the mechanical properties of samples with dimensions equivalent to those required by MEMS devices, the development of new methods was required. The method developed here is intended for the fatigue testing of samples measuring ≈ 10µm (B) x 20µm (W) x 40µm (L). This is completed using a machine recently developed at Tokyo Institute of Technology to load samples of lamellar γ-TiAl based material to failure in compressive bending. This method is intended to work alongside methods previously developed for the fracture toughness testing of similar microsized cantilever bend specimens.In this work sample cantilevers of Alloy 7 are Focussed Ion Beam (FIB) machined from foil ≈ 20µm thick and their stress -life (S-N) fatigue behaviour evaluated. The dependence of fatigue life upon lamellar orientation for a given peak stress / stress range is considered. The effect of the reduced scale of these samples upon the mean and scatter of these sample lifetimes is also considered through comparison with previous data obtained from the S-N testing of macrosized samples of the same material.

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Fracture Behavior of Micro-Sized Ni-P Amorphous Alloy Specimens

Cited by 12 publications

References 3 publications

Fracture toughness testing of nanocrystalline alumina and fused quartz using chevron-notched microbeams

Fracture toughness testing of nanocrystalline alumina and fused quartz using chevron-notched microbeams

Fatigue and fracture of a Ni–P amorphous alloy thin film on the micrometer scale

Fatigue Testing of microsized samples of γ-TiAl based material

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