Micro Fracture Toughness Testing of TiAl Based Alloys with a Fully Lamellar Structure

2004 ◽  
Vol 842 ◽  
Author(s):  
K. Takashima ◽  
T. P. Halford ◽  
D. Rudinal ◽  
Y. Higo ◽  
M. Takeyama
Keyword(s):  
Fracture Toughness ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Testing Machine ◽  
High Fracture Toughness ◽  
Fracture Mechanisms ◽  
High Fracture ◽  
Fundamental Information ◽  
Micrometer Scale ◽  
Fully Lamellar

ABSTRACTA micro-sized testing technique has been applied to investigate the fracture properties of lamellar colonies in a fully lamellar Ti-46Al-5Nb-1W alloy. Micro-sized cantilever specimens with a size ≈ 10 × 10 × 50 μm3 were prepared by focused ion beam machining. Notches with a width of 0.5 μm and a depth of 5 μm were also introduced into the micro-sized specimens by focused ion beam machining. Fracture tests were successfully completed using a mechanical testing machine for micro-sized specimens at room temperature. The fracture toughness (KQ) values obtained were in the range 1.4–7 MPam1/2. Fracture surface observations indicate that these variations are attributable to differences in local lamellar orientations ahead of the notch. These fracture toughness values are also lower than those having been previously reported in conventional samples. This may be due the absence of significant extrinsic toughening mechanisms in these micro-sized specimens. Fracture mechanisms of these alloys are also considered on the micrometer scale. The results obtained in this investigation give important and fundamental information on the development of TiAl based alloys with high fracture toughness.

Experiment Research for Fracture Toughness of PAN-Based Carbon Fibers

2011 ◽  
Vol 462-463 ◽  
pp. 1361-1366 ◽  
Author(s):  
Bo Ming Zhang ◽  
Yu Fen Wu
Keyword(s):  
Fracture Toughness ◽  
Tensile Strength ◽  
Carbon Fibers ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Testing Machine ◽  
High Strength ◽  
Carbon Filaments ◽  
Fracture Theory ◽  
In Virtue Of

For the sake of the carbon filaments’ fracture toughness, using the focused ion beam (FIB) to etch the carbon fibers and got different tensile strength, and all specimens were stretched on an Instron-type filaments testing machine and got the samples’ tensile strength, The crack-to-mirror size ratio was assumed as a constant, In virtue of Griffith fracture theory, Fracture toughness (KΙC) of representative high-strength type PAN (polyacrylonitrile)-based carbon fibers, Torayca T300 and T800, were estimated to be 1MPam1/2 from the tensile strength vs. fracture mirror size relation.

Microscale Fracture Toughness Testing of TiAl PST Crystals

2008 ◽  
Vol 1128 ◽  
Author(s):  
Daisuke Miyaguchi ◽  
Masaaki Otsu ◽  
Kazuki Takashima ◽  
Masao Takeyama
Keyword(s):  
Fracture Toughness ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Testing Machine ◽  
Type Specimens ◽  
Toughening Mechanisms ◽  
Two Phase ◽  
Fracture Toughness Testing ◽  
Crack Wake ◽  
Toughness Testing

AbstractA microscale fracture testing technique has been applied to examine the fracture properties of lamellar in TiAl PST crystals. Micro-sized cantilever specimens with a size ˜ 10×20×50 μm3 were prepared from Ti-48Al two-phase single crystals (PST) lamellar by focused ion beam (FIB) machining. Notches with a width of 0.5 μm and a depth of 5 μm were also introduced into the specimens by FIB. Two types of notch directions (interlamellar and translamellar) were selected when introducing the notches. Fracture tests were successfully completed using a mechanical testing machine for micro-sized specimens at room temperature. The fracture toughness (KQ) values of the interlamellar type specimens were obtained in the range 1.5–3.6 MPam1/2, while those of the translamellar specimens were 5.0–8.1 MPam1/2. These fracture toughness values are lower than those having been previously reported in conventional TiAl PST samples. For macro-sized specimens, extrinsic toughening mechanisms, including shear ligament bridging, act in the crack wake, and the crack growth resistance increases rapidly with increasing length of crack wake for lamellar structured TiAl alloys. In contrast, the crack length in microsized specimens is only 2–3 μm. This indicates that extrinsic toughening mechanisms are not activated in micro-sized specimens. This also indicates that intrinsic fracture toughness can be evaluated using microscale fracture toughness testing.

Structural Micro-Layered Ceramics with Surfaces under Tension and Compression with Increasing Apparent Fracture Toughness

2007 ◽  
Vol 336-338 ◽  
pp. 2564-2568 ◽  
Author(s):  
Jakob Kübler ◽  
Gurdial Blugan ◽  
Hans Jelitto ◽  
Gerold A. Schneider ◽  
Richard Dobedoe
Keyword(s):  
Fracture Toughness ◽  
Testing Machine ◽  
High Fracture Toughness ◽  
High Fracture ◽  
Notched Specimens ◽  
Apparent Fracture Toughness ◽  
Tension And Compression ◽  
Different Depths ◽  
Layered Ceramics ◽  
Stiff Testing Machine

Two different designs of high fracture toughness micro-laminate ceramics were produced containing 50 μm thick Si3N4 layers and 100 μm thick Si3N4 + TiN layers. The first design with external tensile layers had a predicted maximum apparent fracture toughness of 10.5 MPa m1/2. The second design with external compressive layers had a predicted maximum apparent fracture toughness of 18.0 MPa m1/2. The fracture toughness of these micro-laminates was tested by the SEVNB method. A stiff testing machine was used to measure the R-curve behavior by observing crack growth in single notched specimens. A soft testing machine was used to measure the R-curve behavior using several specimens with notches at different depths.

Influence of NbC-Addition on Mechanical Properties of WC-Co

2005 ◽  
Vol 498-499 ◽  
pp. 363-368 ◽  
Author(s):  
Wilson Acchar ◽  
Harim Revoredo de Macedo
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Niobium Carbide ◽  
Testing Machine ◽  
High Hardness ◽  
Inert Atmosphere ◽  
High Fracture Toughness ◽  
High Wear Resistance ◽  
High Fracture ◽  
First Results

Cemented carbides have been intensively used as cutting tool through their high hardness, high fracture toughness and high wear resistance. A considerable amount of works has been developed in order to improve the mechanical properties of alternate cemented carbide systems. This work has the purpose to reports the first results obtained to WC-Co reinforced with 5 wt.% NbC. The mixture of powders was hot-pressed at 1250 °C in a inert atmosphere. Hardness and fracture toughness were carried out in a Vickers hardness testing machine. The results have showed that the addition of niobium carbide improves the hardness of tungsten carbide and inhibits the WCgrain growth.

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

1999 ◽  
Vol 605 ◽  
Author(s):  
Y. Ichikawa ◽  
S. Maekawa ◽  
K. Takashima ◽  
M. Shimojo ◽  
Y. Higo ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Stress Concentration ◽  
Amorphous Alloy ◽  
Fracture Behavior ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Testing Machine ◽  
The Other ◽  
Root Radius ◽  
The Difference

AbstractFracture behavior of micro-sized Ni-P Amorphous alloy specimens has been investigated using a newly developed mechanical testing machine. Specimens with dimensions of 10 × 12 × 50 μm were prepared by focused ion beam machining. Two types of specimens with different crack geometries were prepared. One specimen has a notch with root radius is 0.25 μtm and the other has a fatigue pre-crack. The shapes of the loaddisplacement curves are different for each type of specimen. The fracture strength of the specimens with a notch is higher than that with a fatigue pre-crack and the fracture surfaces of the specimens are also different for each type of specimen. This may be due to the difference in stress concentration at the crack (notch) tip, and indicates that even a notch with a root radius of 0.25 μm is not able to be regarded as a crack for micro-sized specimens. Therefore, the introduction of a fatigue pre-crack is essential for the evaluation of fracture toughness for such micro-sized specimens.

Structural influences of two-dimensional and three-dimensional carbon/epoxy composites on mode I fracture toughness behaviors with rate effects on damage evolution

2018 ◽  
Vol 50 (1) ◽  
pp. 23-45 ◽  
Author(s):  
Amna Siddique ◽  
Baozhong Sun ◽  
Bohong Gu
Keyword(s):  
Fracture Toughness ◽  
Three Dimensional ◽  
Woven Composites ◽  
High Fracture Toughness ◽  
Fracture Mechanisms ◽  
Mode I ◽  
Two Dimensional ◽  
Woven Composite ◽  
High Fracture ◽  
3D Woven Composites

This paper reports the mode I interlaminar fracture toughness and fracture mechanisms of two-dimensional (2D) plain woven composite and three-dimensional (3D) angle-interlock woven composite. The fracture toughness behaviors were tested with double cantilever beam method at the different loading rates from 0.5 to 100 mm/min. Critical strain energy release rate was calculated to compare the difference between the 2D and the 3D woven composites. The fractographs were photographed with scanned electronic microscopy and optical microscopy to show the fracture morphologies. We found that the 3D angle-interlock woven composite has high fracture toughness than that of 2D woven composite. The binder yarns resist the crack initiation and propagation to increase the fracture toughness. While the lower in-plane stiffness of the 3D woven composites should be considered fully for designing the 3D woven composites.

Fracture Behavior of Micro-Sized Specimens Prepared from a TiAl Thin Foil

2003 ◽  
Vol 795 ◽  
Author(s):  
K. Takashima ◽  
T. P. Halford ◽  
D. Rudinal ◽  
Y. Higo ◽  
P. Bowen
Keyword(s):  
Focused Ion Beam ◽  
Ion Beam ◽  
Testing Machine ◽  
Lamellar Microstructure ◽  
Thin Foil ◽  
Type Specimens ◽  
Thin Foils ◽  
Fracture Tests ◽  
Micro Cantilever ◽  
Fully Lamellar

ABSTRACTFracture tests have been carried out on micro-sized specimens prepared from a fully lamellar γ-TiAl based alloy thin foil. Micro cantilever beam type specimens with dimensions = 50 × 10 × 20 μm were prepared from one lamellar colony of the thin foil by focused ion beam machining. Notches with a width of 0.5 μm and a depth of 10 μm were also introduced into the micro-sized specimens by focused ion beam machining. Notch directions were introduced into samples in order to select the trans- and inter-lamellar directions, respectively. Fracture tests were carried out using a mechanical testing machine for micro-sized specimens. Fracture tests for the micro-sized specimens were performed successfully, showing the fracture behaviour to be dependent upon the notch orientation. The fracture toughness of specimens with a notch direction perpendicular to the lamellar direction was 4.7 – 6.9 MPam1/2, while that with a notch direction in the inter-lamellar direction was 1.4 – 2.7 MPm1/2. This indicates that the orientation of the lamellar microstructure greatly affects the fracture properties of micro-sized components prepared from fully lamellar γ-TiAl based alloy thin foils. It is required to consider the results obtained in this investigation when designing actual micro scale structures using TiAl thin foils.

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.

Development of Fatigue Pre-Cracking Method into Micro-Sized Specimens for Measuring Fracture Toughness

2002 ◽  
Vol 741 ◽  
Author(s):  
K. Takashima ◽  
S. Koyama ◽  
K. Nakai ◽  
Y. Higo
Keyword(s):  
Fracture Toughness ◽  
Fatigue Crack ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Testing Machine ◽  
Alloy Thin Film ◽  
Far Field ◽  
Type Specimens ◽  
Beam Type ◽  
Micro Cantilever

ABSTRACTIn our previous investigations [1, 2], we have demonstrated that the introduction of fatigue pre-crack ahead of a notch is required to measure reliable fracture toughness values even for micro-sized specimens. However, it is rather difficult to introduce a fatigue pre-crack into a micro-sized specimen as once a fatigue crack starts to grow then the fatigue fracture occurs within one thousand cycles and this makes it extremely difficult to control fatigue crack length. Therefore, a new fatigue pre-cracking method is required for measuring fracture toughness. In this investigation, a new fatigue pre-cracking method has been proposed for micro-sized specimens and fracture toughness tests were carried out for the micro-sized specimens with fatigue pre-crack. Micro-cantilever beam type specimens with dimensions of 10 × 10 × 50 μm3 were prepared from an electroless deposited Ni-P amorphous alloy thin film and notches were introduced by focused ion beam machining. Fatigue pre-cracks were introduced ahead of the notches by far-field cyclic compression method using a mechanical testing machine for micro-sized specimens (MFT2000). Fracture tests were also carried out using the testing machine. Fatigue pre-cracks with length of 0.2 μm were confirmed on the fracture surfaces ahead of the notches in the far-field cyclically compressed specimens. This indicates that the fatigue pre-cracking method developed in this investigation is promising for measuring accurate fracture toughness for micro-sized specimens for MEMS applications.

scholarly journals Microfracture Test of Mg12ZnY Intermetallic Compound in Mg-Zn-Y Alloys

2011 ◽  
Vol 1295 ◽  
Author(s):  
Hajime Yoshimura ◽  
Shun Matsuyama ◽  
Mitsuhiro Matsuda ◽  
Masaaki Otsu ◽  
Kazuki Takashima ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Intermetallic Compound ◽  
Magnesium Alloys ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Testing Machine ◽  
Crack Orientation ◽  
Fracture Properties ◽  
Superior Mechanical Properties

ABSTRACTA Mg-Zn-Y alloy including a Mg12ZnY intermetallic compound exhibits excellent mechanical properties as compared to conventional magnesium alloys. The superior mechanical properties of this alloy seem to originate from the Mg12ZnY intermetallic compound; however, the mechanical properties of Mg12ZnY itself have not yet been fully investigated owing to the small size of this compound. In this study, a microfracture test was performed to investigate the fracture properties of the Mg12ZnY intermetallic compound. The material used in this test was a Mg88Zn5Y7 alloy. Micro-sized cantilever specimens composed of Mg12ZnY, with dimensions of 10 × 20 × 50 μm3, were prepared selectively isolated from the Mg88Zn5Y7 alloy using focused ion beam (FIB) machining. Notches with a width of 0.5 μm and a depth of 5 μm were also introduced into the micro-sized specimens. Microfracture tests were performed using a mechanical testing machine for microscale materials. The fracture toughness values (KQ) of Mg12ZnY were 1.2−3.0 MPam1/2. TEM observations indicated that the KQ values were dependent on the crack orientation in Mg12ZnY, with the higher KQ values correlating with cracks propagating parallel to the c-axis of Mg12ZnY. This suggests that the fracture toughness of Mg-Zn-Y alloys can be improved by controlling the orientation of the Mg12ZnY compound.

Sign in / Sign up

Export Citation Format

Share Document