scholarly journals The Hardening in Alloys and Composites and Its Examination with a Diffraction and Self-Consistent Model

2018 ◽  
Vol 2018 (10) ◽  
pp. 31-46
Author(s):  
Elżbieta Gadalińska ◽  
Andrzej Baczmański ◽  
Sebastian Wroński ◽  
Mirosław Wróbel ◽  
Christian Scheffzük
Keyword(s):  
Tensile Test ◽  
Stress Measurement ◽  
Hardening Process ◽  
Consistent Model ◽  
Self Consistent ◽  
Hardening Parameter ◽  
Critical Resolved Shear Stress ◽  
The Impact

Abstract The paper presents the results of diffraction stress measurement in Al/SiC composite and in 2124T6 aluminum alloy during the in situ tensile test. The main aim of the work is to observe the stress values for different stages of tensile test for the composite after applying two types of thermal treatment and for the alloy used as a matrix in this composite, to identify the type of hardening process. The experimental results were compared against the calculations results obtained from the self-consistent model developed by Baczmański [1] - [3] to gain the information about the micromechanical properties (critical resolved shear stress τcr and hardening parameter H) of the examined materials. This comparison allowed researchers to determine the role of reinforcement in the composite as well as the impact of the heat treatment on the hardening of the material.

Localization of Stresses in Polycrystalline Grains Measured by Neutron Diffraction and Predicted by Self-Consistent Model

2011 ◽  
Vol 681 ◽  
pp. 103-108
Author(s):  
Anita Gaj ◽  
Lea le Joncour ◽  
Andrzej Baczmanski ◽  
Sebastian Wroński ◽  
Benoit Panicaud ◽  
...  
Keyword(s):  
Neutron Diffraction ◽  
Load Transfer ◽  
Diffraction Method ◽  
Lattice Strains ◽  
Consistent Model ◽  
Self Consistent ◽  
Main Component ◽  
Critical Resolved Shear Stress ◽  
Elastic Lattice

Time of flight neutron diffraction method was applied to measure elastic lattice strains in austenitic steel during "in situ" tensile test. Comparing experimental data with self-consistent model, the critical resolved shear stress and hardening parameters were determined for polycrystalline grains. The result allowed us to determine the main component of the stress localization tensor, relating the rate of grain stress with the applied macrostress rate. The evolution of concentration tensor in function of the applied macrostress was analyzed. Finally, the load transfer between grains during yielding of the sample was studied.

scholarly journals Preoperative breast magnetic resonance imaging in patients with ductal carcinoma in situ: a systematic review for the European Commission Initiative on Breast Cancer (ECIBC)

2021 ◽  
Author(s):  
Carlos Canelo-Aybar ◽  
Alvaro Taype-Rondan ◽  
Jessica Hanae Zafra-Tanaka ◽  
David Rigau ◽  
Axel Graewingholt ◽  
...  
Keyword(s):  
Ductal Carcinoma In Situ ◽  
Surgical Outcomes ◽  
Carcinoma In Situ ◽  
Ductal Carcinoma ◽  
Breast Conserving Surgery ◽  
Cochrane Library ◽  
Treatment Change ◽  
The Impact

Abstract Objective To evaluate the impact of preoperative MRI in the management of Ductal carcinoma in situ (DCIS). Methods We searched the PubMed, EMBASE and Cochrane Library databases to identify randomised clinical trials (RCTs) or cohort studies assessing the impact of preoperative breast MRI in surgical outcomes, treatment change or loco-regional recurrence. We provided pooled estimates for odds ratios (OR), relative risks (RR) and proportions and assessed the certainty of the evidence using the GRADE approach. Results We included 3 RCTs and 23 observational cohorts, corresponding to 20,415 patients. For initial breast-conserving surgery (BCS), the RCTs showed that MRI may result in little to no difference (RR 0.95, 95% CI 0.90 to 1.00) (low certainty); observational studies showed that MRI may have no difference in the odds of re-operation after BCS (OR 0.96; 95% CI 0.36 to 2.61) (low certainty); and uncertain evidence from RCTs suggests little to no difference with respect to total mastectomy rate (RR 0.91; 95% CI 0.65 to 1.27) (very low certainty). We also found that MRI may change the initial treatment plans in 17% (95% CI 12 to 24%) of cases, but with little to no effect on locoregional recurrence (aHR = 1.18; 95% CI 0.79 to 1.76) (very low certainty). Conclusion We found evidence of low to very low certainty which may suggest there is no improvement of surgical outcomes with pre-operative MRI assessment of women with DCIS lesions. There is a need for large rigorously conducted RCTs to evaluate the role of preoperative MRI in this population. Key Points • Evidence of low to very low certainty may suggest there is no improvement in surgical outcomes with pre-operative MRI. • There is a need for large rigorously conducted RCTs evaluating the role of preoperative MRI to improve treatment planning for DCIS.

The development of intergranular strains in a high-strength steel

1998 ◽  
Vol 33 (5) ◽  
pp. 373-383 ◽  
Author(s):  
J W L Pang ◽  
T M Holden ◽  
T E Mason
Keyword(s):  
High Strength ◽  
Stress Axis ◽  
Low Alloy Steel ◽  
Uniaxial Load ◽  
Consistent Model ◽  
Self Consistent ◽  
In Situ Neutron Diffraction ◽  
Small Plastic Deformation ◽  
Intergranular Strains

In situ neutron diffraction measurements have been made on a high-strength low-alloy steel to study the generation of intergranular strains under uniaxial load. Intergranular strains were found to be actively developed at small plastic deformation (< 4.5 per cent) and stay unchanged in subsequent loadings. Large tensile strains of an average 7 × 10−4 were observed for the (002) reflections transverse to the stress axis whereas intergranular effects are comparatively insignificant for other reflections. Experimental results were found to be in excellent agreement with the predictions based on the elastoplastic self-consistent model.

Study of Micromechanical Behaviour of Two Phase Polycrystalline Materials Using Diffraction and Self Consistent Model

2014 ◽  
Vol 783-786 ◽  
pp. 2059-2064
Author(s):  
Andrzej Baczmański ◽  
Elżbieta Gadalińska ◽  
Chedly Braham ◽  
Sebastian Wroński ◽  
Lea le Joncour ◽  
...  
Keyword(s):  
Lattice Strain ◽  
Polycrystalline Materials ◽  
X Ray Diffraction ◽  
Two Phase ◽  
X Ray ◽  
Consistent Model ◽  
Self Consistent ◽  
In Situ Deformation ◽  
Specific Orientation

Diffraction methods for lattice strain measurement provide useful information concerning the nature of grains behaviour during elastoplastic deformation. The main advantage of the diffraction methods is the possibility of studying mechanical properties of polycrystalline materials separately in each phase and in groups of grains with a specific orientation. In this work we present application of the neutron and X-ray diffraction to study “in situ” deformation of two phase stainless steels during tensile loading. The experimental results are compared with self-consistent model.

scholarly journals Isolating the Role of the Node-Linker Bond in the Compression of UiO-66 Metal-Organic Frameworks

2020 ◽  
Author(s):  
Louis Redfern ◽  
Maxime Ducamp ◽  
Megan C. Wasson ◽  
Lee Robison ◽  
Florencia Son ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Density Functional ◽  
Metal Organic Frameworks ◽  
Coordination Bond ◽  
Metal Organic ◽  
Dft Simulations ◽  
The Impact ◽  
Organic Linker

Understanding the mechanical properties of metal–organic frameworks (MOFs) is essential to the fundamental advancement and practical implementations of porous materials. Recent computational and experimental efforts have revealed correlations between mechanical properties and pore size, topology, and defect density. These results demonstrate the important role of the organic linker in the response of these materials to physical stresses. However, the impact of the coordination bond between the inorganic node and organic linker on the mechanical stability of MOFs has not been thoroughly studied. Here, we isolate the role of this node–linker coordination bond to systematically study the effect it plays in the compression of a series of isostructural MOFs, M-UiO-66 (M = Zr, Hf, or Ce). The bulk modulus (i.e. the resistance to compression under hydrostatic pressure) of each MOF is determined by in situ diamond anvil cell (DAC) powder X-ray diffraction measurements and density functional theory (DFT) simulations. These experiments reveal distinctive behavior of Ce-UiO-66 in response to pressures under one GPa. In situ DAC Raman spectroscopy and DFT calculations support the observed differences in compressibility between Zr-UiO-66 and the Ce- analogue. Monitoring changes in bond lengths as a function of pressure through DFT simulations provides a clear picture of those which shorten more drastically under pressure and those which resist compression. This study demonstrates that changes to the node–linker bond can have significant ramifications on the mechanical properties of MOFs.

scholarly journals Isolating the Role of the Node-Linker Bond in the Compression of UiO-66 Metal-Organic Frameworks

2020 ◽  
Author(s):  
Louis Redfern ◽  
Maxime Ducamp ◽  
Megan C. Wasson ◽  
Lee Robison ◽  
Florencia Son ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Density Functional ◽  
Metal Organic Frameworks ◽  
Coordination Bond ◽  
Metal Organic ◽  
Dft Simulations ◽  
The Impact ◽  
Organic Linker

Understanding the mechanical properties of metal–organic frameworks (MOFs) is essential to the fundamental advancement and practical implementations of porous materials. Recent computational and experimental efforts have revealed correlations between mechanical properties and pore size, topology, and defect density. These results demonstrate the important role of the organic linker in the response of these materials to physical stresses. However, the impact of the coordination bond between the inorganic node and organic linker on the mechanical stability of MOFs has not been thoroughly studied. Here, we isolate the role of this node–linker coordination bond to systematically study the effect it plays in the compression of a series of isostructural MOFs, M-UiO-66 (M = Zr, Hf, or Ce). The bulk modulus (i.e. the resistance to compression under hydrostatic pressure) of each MOF is determined by in situ diamond anvil cell (DAC) powder X-ray diffraction measurements and density functional theory (DFT) simulations. These experiments reveal distinctive behavior of Ce-UiO-66 in response to pressures under one GPa. In situ DAC Raman spectroscopy and DFT calculations support the observed differences in compressibility between Zr-UiO-66 and the Ce- analogue. Monitoring changes in bond lengths as a function of pressure through DFT simulations provides a clear picture of those which shorten more drastically under pressure and those which resist compression. This study demonstrates that changes to the node–linker bond can have significant ramifications on the mechanical properties of MOFs.

scholarly journals Role of Si3N4 on microstructure and hardness of hot-pressed ZrB2−SiC composites

2021 ◽  
Vol 1 (1) ◽  
pp. 34-40
Author(s):  
Zahra Bahararjmand ◽  
Mohammad A. Khalilzadeh ◽  
Farshad Saberi-Movahed ◽  
Tae Hyung Lee ◽  
Jinghan Wang ◽  
...  
Keyword(s):  
Relative Density ◽  
Vickers Hardness ◽  
Raw Materials ◽  
Soft Phase ◽  
Negative Effect ◽  
Sic Composites ◽  
The Impact ◽  
Positive Effect

The impact of Si3N4 content on the hardness and microstructural developments of ZrB2-SiC material has been investigated thoroughly in the present investigation. Having prepared the raw materials in a jar mill, the ZrB2-SiC samples containing various amounts of Si3N4 were hot-pressed at 1850 °C. Furthermore, XRD, FESEM, and HRTEM were utilized to evaluate the microstructure of samples. The formation of in-situ h-BN was proved by the mentioned methods. Also, it was shown that the Vickers hardness of ZrB2-SiC increases up to 20 GPa in presence of 4.5 wt% Si3N4 which is 3 GPa more than the sample without Si3N4. Results show that the positive effect of increased relative density on hardness is more than the negative effect of h-BN soft phase formation.

scholarly journals Cloud impacts on photochemistry: a new climatology of photolysis rates from the Atmospheric Tomography mission

2018 ◽  
Author(s):  
Samuel R. Hall ◽  
Kirk Ullmann ◽  
Michael J. Prather ◽  
Clare M. Flynn ◽  
Lee T. Murray ◽  
...  
Keyword(s):  
Tropospheric Chemistry ◽  
Transport Models ◽  
Clear Sky ◽  
Photolysis Rates ◽  
Four Seasons ◽  
The Pacific ◽  
Greenhouse Effects ◽  
The Impact

Abstract. Measurements from actinic flux spectroradiometers on board the NASA DC-8 during the Atmospheric Tomography (ATom) mission provide an extensive set of statistics on how clouds alter photolysis rates (J-values) throughout the remote Pacific and Atlantic Ocean basins. ATom made profiling circumnavigations of the troposphere over four seasons during 2016–2018. J-values are a primary chemical control over tropospheric ozone and methane abundances and their greenhouse effects. Clouds have been recognized for more than three decades as being an important factor in tropospheric chemistry. The ATom climatology of J-values is a unique test of how the chemistry models treat clouds. This work focuses on measurements over the Pacific during the first deployment (ATom-1) in August 2016. Nine global chemistry–climate or –transport models provide J-values for the domains measured in ATom-1. We compare mean profiles over a range of cloudy and clear conditions; but, more importantly, we build a statistical picture of the impact of clouds on J-values through the distribution of the ratio of J-cloudy to J-clear. In detail, the models show largely disparate patterns. When compared with measurements, there is some limited, broad agreement. Models here have resolutions of 50–200 km and thus reduce the occurrence of clear sky when averaging over grid cells. In situ measurements also average the scattered sunlight, but only out to scales of 10 s of km. A primary uncertainty remains in the role of clouds in chemistry, in particular, how models average over cloud fields, and how such averages can simulate measurements.

scholarly journals On the High Formability of AZ31-0.5Ca Magnesium Alloy

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2201 ◽  
Author(s):  
Umer Masood Chaudry ◽  
Tae Hoo Kim ◽  
Sang Duck Park ◽  
Ye Sik Kim ◽  
Kotiba Hamad ◽  
...  
Keyword(s):  
Az31 Alloy ◽  
Mg Alloy ◽  
Slip Systems ◽  
Basal Texture ◽  
Consistent Model ◽  
Az31 Mg Alloy ◽  
Self Consistent ◽  
Grain Misorientation ◽  
Critical Resolved Shear Stress ◽  
Electron Back Scattered Diffraction

In this work, we investigated the effect of Ca on the formability of the AZ31 Mg alloy. For this purpose, the microstructure, texture, mechanical properties and formability of AZ31 Mg alloy samples containing 0.5 wt. % Ca (AZ31-0.5Ca) were studied. For comparison, the performance of Ca-Free AZ31 alloy samples with similar grain size was also investigated. In addition, formability of this alloy was reached at a high punch speed. The results of this work showed that the addition of 0.5 wt. % Ca can enhance the formability of the AZ31 alloy, which was three times greater than that of the Ca-Free AZ31 alloy. The improved formability was attributed to the formation of (Mg,Al)2Ca particles (~1 μm), which, in turn, contribute to reducing the intensity of the strong basal texture during the primary processing of the alloy. The in-grain misorientation axis analysis determined by electron back-scattered diffraction and critical resolved shear stress calculations carried out by the viscoplastic self-consistent model showed that the non-basal slip systems could be activated in the AZ31-0.5Ca alloy.

Sign in / Sign up

Export Citation Format

Share Document