Evaluationof fracture toughness ofalpha-Nb5Si3 by micro-sized cantilever beam testing

2015 ◽  
Vol 1760 ◽  
Author(s):  
Shiori Suzuki ◽  
Nobuaki Sekido ◽  
Takahito Ohmura ◽  
Seiji Miura
Keyword(s):  
Fracture Toughness ◽  
Room Temperature ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Small Scale ◽  
Testing Method ◽  
Yielding Condition ◽  
Linear Load ◽  
Scale Yielding ◽  
Fracture Tests

ABSTRACTA micro-sized fracture testing method has been applied to investigate fracture toughness of alpha-Nb5Si3. Chevron-notched single crystal specimens with a size of 3 x 3 x 15 μm3 were prepared in a grain of polycrystalline alpha-Nb5Si3 by focused ion beam, FIB, technique. Fracture tests were conducted using a nanoindenter at room temperature and linear load-displacement curves and smooth fracture surfaces were obtained. This fracture behavior was presumed to be brittle fracture similar to bulk alpha-Nb5Si3. The average of fracture toughness KQ is 3.45 ± 0.29 MPa√m under a small-scale yielding condition.

Microscale Fracture Testing of Mg-Zn-Y

2009 ◽  
Vol 1225 ◽  
Author(s):  
Shun Matsuyama ◽  
Tetsuya Sakamoto ◽  
Masaaki Otsu ◽  
Kazuki Takashima ◽  
Yoshihito Kawamura
Keyword(s):  
Fracture Toughness ◽  
Room Temperature ◽  
Focused Ion Beam ◽  
Volume Fraction ◽  
Ion Beam ◽  
Testing Machine ◽  
Alloy Specimen ◽  
Testing Technique ◽  
Lpso Phase ◽  
Fracture Tests

AbstractA microfracture testing technique was applied for investigating the fracture properties of Mg-Zn-Y alloys with a long-period stacking ordered (LPSO) phase. Microsized cantilever beam specimens with dimensions ≈ 10×20×50 μm3 were prepared from Mg-Zn-Y alloys by focused ion beam (FIB) machining. Notches with widths of 0.5 μm and depths of 3.5–5 μm were also introduced into the specimens by FIB machining. In this study, three types of Mg-Zn-Y alloys―Mg99.2Zn0.2Y0.6, Mg97Zn1Y2, and Mg88Zn5Y7―were used. Fracture tests were successfully conducted using a mechanical testing machine for microsized specimens at room temperature. The fracture toughness values (KIC) could not be obtained as the specimen size was too small to satisfy the plane strain condition. Hence, provisional KQ values were considered. The KQ values of the Mg97Zn1Y2 alloy were 0.8–1.2 MPam½, and those of the Mg88Zn5Y7 alloy were 1.2–3.0 MPam½. As the fracture in the Mg99.2Zn0.2Y0.6 alloy specimen occurred in a ductile plastic deformation, it was impossible to evaluate KQ values of this specimen. The increasing volume fraction of the LPSO phase indicates that the fracture toughness of Mg-Zn-Y alloys increases in LPSO phase.

Toughening of Brittle Materials by Dislocation Cells

2001 ◽  
Vol 7 (S2) ◽  
pp. 420-421
Author(s):  
H. Saka ◽  
W.-J. Moon ◽  
S. Horiuchi ◽  
S. Uchimura
Keyword(s):  
Fracture Toughness ◽  
Room Temperature ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Brittle Materials ◽  
Thin Foil ◽  
Vickers Indentation ◽  
Transmission Electron ◽  
Dislocation Cells ◽  
Metallurgical Processes

Many attempts have been made to improve the fracture toughness of brittle materials such as ceramics. Most of the methods developed so far make use of metallurgical processes, for example, phase transformation, refining of grains, formation of composite materials. However, these methods can not be applied universally to brittle materials which do not have such a useful metallurgical processes.Moon and Saka (1) recently showed that the fracture toughness Klc of a YAG single crystal the sub-surface of which is damaged by micro-Vickers indentation at room temperature, followed by annealing at high temperatures is improved by a factor 2 from 1.13 to 2.26MPam1/2. The fracture toughness Klc was evaluated by measuring the length of cracks which initiate at the corner of Vickers indentation(2). Transmission electron microscopy of the subsurface reveals the healing of cracks introduced by room-temperature indentation and formation of dislocation cells. The thin foil specimens were prepared using a focused ion beam (FIB) technique(3).

Fracture Toughness in Ultra Fine-Grained Magnesium Alloy

2006 ◽  
Vol 503-504 ◽  
pp. 155-160 ◽  
Author(s):  
Hidetoshi Somekawa ◽  
Toshiji Mukai
Keyword(s):  
Fracture Toughness ◽  
Grain Size ◽  
Magnesium Alloy ◽  
Small Scale ◽  
Plane Strain Fracture Toughness ◽  
Small Scale Yielding ◽  
Fine Grained ◽  
Yielding Condition ◽  
Strain Fracture ◽  
Scale Yielding

The fracture toughness was investigated using in an extruded AZ31 magnesium alloy with an initial grain size of 1.0 μm. Since the small scale yielding condition was not satisfied with the present thin thickness, the value of plane-strain fracture toughness, KIC = 27.9 MPam1/2, was measured from Stretched Zone analysis. The values of KIC in AZ31 magnesium alloys were dependent on the grain size. The grain refinement was found to be one of the improvement methods for fracture toughness in magnesium alloy.

Effects of Sample Size on the Fracture Behavior in Fe-3%Si Alloy Single Crystals

2006 ◽  
Vol 976 ◽  
Author(s):  
Kazuki Takashima ◽  
Eiji Taki ◽  
Yuji Kawakami ◽  
Masaaki Otsu
Keyword(s):  
Plastic Zone ◽  
Single Crystal ◽  
Fracture Behavior ◽  
Large Scale ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Plastic Zone Size ◽  
Alloy Single Crystal ◽  
Small Scale ◽  
Scale Yielding

AbstractFracture tests have been performed for both macro- and micro-sized specimens prepared from an Fe-3%Si alloy single crystal, and the effects of length scale on fracture behavior have been investigated. Micro-sized cantilever beam specimens with dimensions of 10 × 10 × 50 μm3 were prepared by focused ion beam machining. Notches with a depth of 5 μm were introduced into the micro-sized specimens and fatigue pre-crack was also introduced ahead of the notch. Macro-sized three-point bending specimens with dimensions of 2 × 2 × 10 mm3 were also cut from the same Fe-3%Si alloy single crystal. Notches with a depth of 1mm were introduced into the macro-sized specimens, and fatigue pre-crack was also introduced. Notch plane was set to be (100), which is a cleavage plane of this material, and notch direction was set to be [010] for both size of specimens. For macro-sized specimens, cleavage fracture occurred during introducing fatigue pre-crack. In contrast, the micro-sized specimens were fractured by ductile manner. A plastic zone was clearly observed on the specimen surface near the crack tip and dimples were found on the fracture surface. The plastic zone size of this material is calculated to be 90 μm. This size is small enough to satisfy small scale yielding for macro-sized specimens, although this size corresponds to large scale yielding in micro-sized specimens. This may cause the size effect on the fracture behavior of this material.

Application of SDS Method to Predict Fracture Toughness Temperature Dependency of A533B Steel

2017 ◽  
Author(s):  
Toshiyuki Meshii ◽  
Kenichi Ishihara ◽  
Hiroki Nakano
Keyword(s):  
Fracture Toughness ◽  
Master Curve ◽  
Tensile Tests ◽  
Fracture Load ◽  
Reference Temperature ◽  
Small Scale ◽  
Temperature Dependency ◽  
Yielding Condition ◽  
Scale Yielding ◽  
Higher Temperature

Recently, the authors have proposed a new method for scaling the crack tip stress distribution under small scale yielding condition and named it as T-scaling method [1, 2]. This method identifies the different stress loads for materials with different tensile properties but identical in terms of K or J. Then by accepting the knowledge “fracture stress for slip induced cleavage fracture is temperature independent [3],” a framework to predict the fracture load Pc and fracture toughness Jc at an arbitrary temperature from the already known Pcr and Jcr at a reference temperature Tr was proposed and validated for 0.55% carbon steel JIS S55C [1, 2]. This framework was named as SDS method. This paper presents that the SDS method was valid to predict 1TCT Jc temperature dependency of A533B steel [4] in the range of −9 ≤ T-T0 ≤ 27 °C, where T0 is the master curve reference temperature. The SDS method seems to have a possibility to solve the problem the master curve is facing in the relatively higher temperature region, by requiring only tensile tests.

Nanocomposite Polyurethane Foams Via POSS Blends

2002 ◽  
Vol 733 ◽  
Author(s):  
Brock McCabe ◽  
Steven Nutt ◽  
Brent Viers ◽  
Tim Haddad
Keyword(s):  
High Temperature ◽  
Sample Preparation ◽  
Room Temperature ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Polyurethane Foams ◽  
Development Projects ◽  
Polymer Systems ◽  
Polyurethane Resin ◽  
Military Development

AbstractPolyhedral Oligomeric Silsequioxane molecules have been incorporated into a commercial polyurethane formulation to produce nanocomposite polyurethane foam. This tiny POSS silica molecule has been used successfully to enhance the performance of polymer systems using co-polymerization and blend strategies. In our investigation, we chose a high-temperature MDI Polyurethane resin foam currently used in military development projects. For the nanofiller, or “blend”, Cp7T7(OH)3 POSS was chosen. Structural characterization was accomplished by TEM and SEM to determine POSS dispersion and cell morphology, respectively. Thermal behavior was investigated by TGA. Two methods of TEM sample preparation were employed, Focused Ion Beam and Ultramicrotomy (room temperature).

Compression of Single-Crystal Micropillars of the Γ Intermetallic Phase in the Fe-Zn System

2014 ◽  
Vol 922 ◽  
pp. 264-269 ◽  
Author(s):  
Masahiro Inomoto ◽  
Norihiko L. Okamoto ◽  
Haruyuki Inui
Keyword(s):  
Single Crystal ◽  
Deformation Behavior ◽  
Room Temperature ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Intermetallic Phase ◽  
Gamma Phase ◽  
Compression Tests ◽  
Slip Direction ◽  
Beam Method

The deformation behavior of the Γ (gamma) phase in the Fe-Zn system has been investigated via room-temperature compression tests of single-crystal micropillar specimens fabricated by the focused ion beam method. Trace analysis of slip lines indicates that {110} slip occurs for the specimens investigated in the present study. Although the slip direction has not been uniquely determined, the slip direction might be <111> in consideration of the crystal structure of the Γ phase (bcc).

Nanocrystals acting as Coulomb islands operating at room temperature created using a focused ion-beam process

2001 ◽  
Vol 79 (1) ◽  
pp. 120-122 ◽  
Author(s):  
T. W. Kim ◽  
D. C. Choo ◽  
J. H. Shim ◽  
M. Jung ◽  
S. O. Kang ◽  
...  
Keyword(s):  
Room Temperature ◽  
Focused Ion Beam ◽  
Ion Beam

scholarly journals Ion Irradiation-Induced Microstructural Evolution of Ni–Mo–Cr Low Alloy Steels

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2268
Author(s):  
Hongying Sun ◽  
Penghui Lei ◽  
Guang Ran ◽  
Hui Wang ◽  
Jiyun Zheng ◽  
...  
Keyword(s):  
Irradiation Dose ◽  
Focused Ion Beam ◽  
Ion Irradiation ◽  
Ion Beam ◽  
High Strength ◽  
Positron Annihilation Spectroscopy ◽  
Small Scale ◽  
Low Alloy Steels ◽  
Dislocation Loops ◽  
S Parameter

As leading candidates of sheet steels for advanced nuclear reactors, three types of Ni–Mo–Cr high-strength low alloy (HSLA) steels named as CNST1, CNST2 and CNSS3 were irradiated by 400 keV Fe+ with peak fluence to 1.4 × 1014, 3.5 × 1014 and 7.0 × 1014 ions/cm2, respectively. The distribution and morphology of the defects induced by the sample preparation method and Fe+ irradiation dose were investigated by transmission electron microscopy (TEM) and positron-annihilation spectroscopy (PAS). TEM samples were prepared with two methods, i.e., a focused ion beam (FIB) technique and the electroplating and twin-jet electropolishing (ETE) method. Point defects and dislocation loops were observed in CNST1, CNST2 and CNSS3 samples prepared via FIB. On the other hand, samples prepared via the ETE method revealed that a smaller number of defects was observed in CNST1, CNST2 and almost no defects were observed in CNST3. It is indicated that artifact defects could be introduced by FIB preparation. The PAS S-W plots showed that the existence of two types of defects after ion implantation included small-scale defects such as vacancies, vacancy clusters, dislocation loops and large-sized defects. The S parameter of irradiated steels showed a clear saturation in PAS response with increasing Fe+ dose. At the same irradiation dose, higher values of the S-parameter were achieved in CNST1 and CNST2 samples when compared to that in CNSS3 samples. The mechanism and evolution behavior of irradiation-induced defects were analyzed and discussed.

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