Temperature and Orientation Dependence of Fracture Behavior of Directionally Solidified Duplex-Phase Crystals Composed of Ni3X-Type Intermetallic Compounds

2006 ◽  
Vol 512 ◽  
pp. 67-72 ◽  
Author(s):  
Koji Hagihara ◽  
Naoyuki Yokotani ◽  
Yukichi Umakoshi
Keyword(s):  
Fracture Toughness ◽  
Temperature Dependence ◽  
Lamellar Structure ◽  
Fracture Behavior ◽  
Orientation Dependence ◽  
Directionally Solidified ◽  
Bending Tests ◽  
Three Point Bending ◽  
Controlling Mechanism ◽  
Fracture Behaviors

Fracture behaviors of three directionally solidified (DS) duplex-phase alloys composed of Ni3Nb(D0a)/Ni3Al(L12), Ni6TaAl(D024)/Ni3Al(L12) and Ni3Ti(D024)/Ni3Si(L12) phases, respectively were investigated by three-point bending tests, focusing on temperature and orientation dependence. The temperature-toughness relation showed dissimilar curves depending on alloy. The increasing rate of fracture toughness was the highest in the Ni3Al/Ni3Nb alloy with fine lamellar structure and was the lowest in the Ni3Al/Ni6TaAl alloy with rod-like precipitates. The controlling mechanism for the temperature dependence of fracture behavior of Ni3Al/Ni3Nb alloys was discussed.

scholarly journals Fracture Behavior of Single-Crystal Sapphire in Different Crystal Orientations

Crystals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 930
Author(s):  
Shizhan Huang ◽  
Jiaming Lin ◽  
Ningchang Wang ◽  
Bicheng Guo ◽  
Feng Jiang ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Surface Roughness ◽  
Single Crystal ◽  
Fracture Behavior ◽  
Three Dimensional ◽  
Fracture Morphology ◽  
High Tech ◽  
Bending Tests ◽  
Three Point Bending ◽  
Single Crystal Sapphire

In order to study the anisotropy of fracture toughness and fracture mechanism of single-crystal sapphire, the three-point bending tests and the single-edge V-notch beam (SEVNB) were used to test the fracture toughness of A-plane, C-plane, and M-plane sapphire, which are widely used in the semiconductor, aerospace, and other high-tech fields. Fracture morphology was investigated by a scanning electron microscope and three-dimensional video microscopy. The fracture toughness and fracture morphology of different crystal planes of sapphire showed obvious anisotropy and were related to the loading surfaces. C-plane sapphire showed the maximal fracture toughness of 4.24 MPa·m1/2, and fracture toughness decreases in the order of C-plane, M-plane, and A-plane. The surface roughness is related to the dissipation of fracture energy. The surface roughness of the fracture surface is in the same order as C-plane > M-plane > A-plane. The fracture behavior and morphology of experiments were consistent with the theoretical analysis. C-plane sapphire cleavages along the R-plane with an angle of 57.6 degrees and the rhombohedral twin were activated. M-plane and A-plane sapphire cleavages along their cross-section.

Fracture behaviors of HVFA-SCC mixed with seawater and sea-sand under three-point bending

2022 ◽  
pp. 136943322110273
Author(s):  
Lingzhu Zhou ◽  
Yu Zheng ◽  
Linsheng Huo ◽  
Yuxiao Ye ◽  
Xiaolu Wang ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Fly Ash ◽  
Unstable Fracture ◽  
Replacement Ratio ◽  
Three Point Bending ◽  
Model Code ◽  
Softening Curve ◽  
Sea Sand ◽  
Fracture Behaviors ◽  
Tensile Softening

This paper aims to study the fracture behaviors of high-volume fly ash-self-compacting concrete (HVFA-SCC) mixed with seawater and sea-sand (SWSS) or freshwater and river sand (FWRS). Three-point bending test were performed on 24 notched beams fabricated with varying in replacement ratio of fly ash (0%, 30%, 50%, and 70%) and the type of water and sand (SWSS and FWRS). The initial and unstable fracture toughness of these test specimens are determined by the double- K fracture model. The effect of fly ash replacement ratio and type of water and sand on the fracture parameters is analyzed and discussed. In addition, the cohesive fracture toughness of all the test specimens is calculated by using Gauss–Chebyshev integral method and the weight function method based on the bilinear tensile softening curve given in CEP-FIP Model Code. A comparison of fracture toughness parameters of determined from the experimental approach and analytical approaches is presented in these SCC specimens. Results show that SCC mixed with SWSS replacing FWRS can improve the unstable fracture toughness and fracture energy, and decrease its brittleness behavior. The cohesive fracture toughness of SWSS-SCC specimens is underestimated by these analytical methods based on the tensile softening curve given in CEP-FIP Model Code.

Fracture Toughness and Cracking Behaviour of SCC Compared to VC

2013 ◽  
Vol 577-578 ◽  
pp. 205-208
Author(s):  
Sara Korte ◽  
Veerle Boel ◽  
Wouter de Corte ◽  
Geert de Schutter
Keyword(s):  
Fracture Toughness ◽  
Fracture Process ◽  
Critical Value ◽  
Fracture Parameter ◽  
Self Compacting Concrete ◽  
Bending Tests ◽  
Three Point Bending ◽  
Notched Specimens ◽  
Subsequent Determination

Vibrated concrete (VC) and self-compacting concrete (SCC) have a substantially different composition, resulting in dissimilar mechanical properties regarding cracking behaviour. The critical value of the mode I stress-intensity factor KICis an appropriate fracture parameter for evaluating fracture toughness and can be obtained from three-point bending tests (3PBT) on small, notched specimens. Subsequent determination of the energy release rate thus allows to examine the crack propagation and fracture process of both concrete types. This paper describes the results of such 3PBTs on samples, made from VC and SCC. Evaluation of the cracking behaviour, derived from these results, reveals remarkable differences.

scholarly journals Study on the Static and Dynamic Fracturing Properties of Marble after Being Damaged Dynamically

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Yunqiu Liu ◽  
Anqi Fu ◽  
Binsong Jiang ◽  
Liyuan Yu ◽  
Xiaobing Wang
Keyword(s):  
Fracture Toughness ◽  
Impact Loading ◽  
Split Hopkinson Pressure Bar ◽  
Cumulative Damage ◽  
Bending Tests ◽  
Three Point Bending ◽  
Cyclic Impact Loading ◽  
Loading Tests ◽  
Cyclic Impact ◽  
The Impact

A split Hopkinson pressure bar (SHPB) system was first used to perform the cyclic impact loading tests on notched semicircular bend (NSCB) marble specimens. Then, static and dynamic three-point bending tests were conducted on these dynamically damaged specimens, respectively. In the cyclic impact loading tests, the dynamic elastic modulus decreases gradually as the impact number increases, but dynamic cumulative damage exhibits a growing trend. In the static and dynamic three-point bending tests, when dynamic cumulative damage is less than 0.345, the dynamic fracture toughness values are larger than the static fracture toughness values, but the experimental data exhibit the opposite results when dynamic cumulative damage ranges from 0.345 to 0.369. Through the quantitative analysis of fracture surface morphologies, the roughness and area of the fracture surfaces increase with an increasing dynamic cumulative damage. Under the same dynamic cumulative damage of the specimens, both the roughness and area of the surfaces fractured by static three-point bending are larger than those fractured by dynamic three-point bending.

scholarly journals Processing and mechanical characterization of Al2O3/Ni and Al2O3/C0 composites by pressureless sintering of nanocomposite powders

2018 ◽  
Vol 12 (2) ◽  
pp. 123-128 ◽  
Author(s):  
Yildiz Kafkaslioğlu ◽  
Hüseyin Yilmaz ◽  
Yahya Tür
Keyword(s):  
Fracture Toughness ◽  
Metallic Phase ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
Bending Tests ◽  
Three Point Bending ◽  
Green Strength ◽  
Nanocomposite Powders ◽  
Hardness Values

Al2O3/Ni and Al2O3/Co nanopowder mixtures (with 3 vol.% of metallic phase) were synthesized by heterogeneous precipitation method. In order to increase the green strength, polypropylene carbonate (PPC) was used as a binder while preparing green compacts. Uniaxially pressed powder mixtures were sintered at 1550?C for 2 h in a reducing atmosphere. The effects of Ni and Co nanophases on the microstructure and mechanical properties of Al2O3 ceramics were studied by X-ray diffraction, scanning electron microscopy, Vickers indentation technique and three-point bending tests. The metallic phase hindered the densification of alumina matrix, yet hardness values of Al2O3, Al2O3/Ni, and Al2O3/Co composites were comparable. Vickers fracture toughness results indicate that the composites have higher fracture toughness, but the characteristic flexural strength and Weibull modulus are higher for the pure Al2O3.

Accounting for Crack Propagation in a Model to Predict Fracture Toughness in Ferritic Steels

2009 ◽  
Author(s):  
Marjorie A. EricksonKirk ◽  
Matthew Wagenhofer ◽  
Paul T. Williams ◽  
Shengjun Yin
Keyword(s):  
Fracture Toughness ◽  
Crack Propagation ◽  
Temperature Dependence ◽  
Propagation Model ◽  
Transgranular Crack ◽  
Deformation And Fracture ◽  
Microcrack Propagation ◽  
Fracture Behaviors ◽  
Parametric Studies ◽  
Ductile To Brittle Transition

A program was undertaken to develop a predictive model of the scatter in toughness of a structural steel across the wide temperature range of ductile-to-brittle transition based on physical understanding of deformation and fracture behaviors. The initial model was focused on microcrack initiation and includes criteria to describe the propagation of particle-sized microcracks into the surrounding ferritic matrix. Parametric studies using this model found that the temperature dependence for fracture toughness, derived from microcrack, was insufficient to describe the temperature dependence observed in measured KJc toughness values. A microcrack propagation model was developed to account for additional barriers associated with transgranular crack propagation to failure. This propagation model accounts for the temperature dependence of crack propagation across grain boundaries and is therefore expected to increase the degree of temperature dependence. This paper summarizes the initiation model and discusses the approach taken in developing a microcrack propagation model component and discusses preliminary results from a Monte Carlo simulation.

Modified Equation To Predict Leak/Rupture Criteria For Axially Through-Wall Notched X80 and X100 Linepipes Having a Higher Charpy Energy

2005 ◽  
Vol 128 (4) ◽  
pp. 572-580 ◽  
Author(s):  
Shinobu Kawaguchi ◽  
Naoto Hagiwara ◽  
Mitsuru Ohata ◽  
Masao Toyoda
Keyword(s):  
Fracture Toughness ◽  
Pipe Material ◽  
Test Results ◽  
Absorbed Energy ◽  
Bending Tests ◽  
Three Point Bending ◽  
Full Scale Tests ◽  
Hoop Stresses ◽  
The Relationship ◽  
Modified Equation

A method of predicting the leak/rupture criteria for API 5L X80 and X100 line pipes was evaluated based on the results of hydrostatic full-scale tests for X60, X65, X80, and X100 line pipes with an axially through-wall (TW) notch. The TW notch test results defined the leak/rupture criteria, that is, the relationship between the initial notch lengths and the maximum hoop stresses during the TW notch tests. The defined leak/rupture criteria were then compared to the prediction of the Charpy V-notch (CVN) absorbed energy-based equation, which has been proposed by Kiefner, Maxey et al. This comparison revealed that the CVN-based equation was not applicable to the pipes having both a CVN energy greater than 120 or 130 J and flow stress greater than the level of X65. In order to predict the leak/rupture criteria for these line pipes, the static absorbed energy for ductile cracking, (Cvs)i, was introduced as representing the fracture toughness of a pipe material. The (Cvs)i value was determined from the microscopic observation of the cut and polished Charpy V-notch specimens after static three-point bending tests. The CVN energy in the original CVN-based equation was replaced by an equivalent CVN energy, (Cv)eq, which was defined as follows: (Cv)eq=4.5(Cvs)i. The leak/rupture criteria for the X80 and X100 line pipes with higher CVN energies were reasonably predicted by the modified equation using the (Cvs)i value.

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