scholarly journals Modelling the Limiting Envelopes of Rocks in the Octahedral Plane

2007 ◽  
Vol 62 (5) ◽  
pp. 683-694 ◽  
Author(s):  
F. Descamps ◽  
J. P. Tshibangu
Keyword(s):  
Octahedral Plane

Observation of Superlattice Dislocations on Cube Planes in Ni3Al

1973 ◽  
Vol 31 ◽  
pp. 174-175 ◽  
Author(s):  
J. M. Oblak ◽  
W. H. Rand
Keyword(s):  
Nearest Neighbor ◽  
Antiphase Boundary ◽  
Nearest Neighbors ◽  
High Energy ◽  
Cross Slip ◽  
Octahedral Plane ◽  
Trapping Mechanism ◽  
Slip Traces

The energy of an a/2 <110> shear antiphase. boundary in the Ll2 expected to be at a minimum on {100} cube planes because here strue ture is there is no violation of nearest-neighbor order. The latter however does involve the disruption of second nearest neighbors. It has been suggested that cross slip of paired a/2 <110> dislocations from octahedral onto cube planes is an important dislocation trapping mechanism in Ni3Al; furthermore, slip traces consistent with cube slip are observed above 920°K.Due to the high energy of the {111} antiphase boundary (> 200 mJ/m2), paired a/2 <110> dislocations are tightly constricted on the octahedral plane and cannot be individually resolved.

Characterization of Polyaniline Nanocomposite Using AC Electrochemical Impedance Spectroscopy

2006 ◽  
Author(s):  
Jianxun Hu ◽  
Dongyan Wang
Keyword(s):  
Mechanical Properties ◽  
Electrochemical Impedance Spectroscopy ◽  
Impedance Spectroscopy ◽  
Polymer Nanocomposites ◽  
Electrochemical Impedance ◽  
Physical And Mechanical Properties ◽  
Octahedral Plane ◽  
Synthetic Mica ◽  
Polyaniline Nanocomposite

Silicate minerals have been found to improve physical and mechanical properties of polymers significantly through clay/polymer nanocomposites. This class of materials uses smectite-type clays, such as hectorite, montmorillonite, magadiite, and synthetic mica, as fillers to enhance the properties of polymers. One of the most important properties of smectite-type clays is their layered structure, in which each layer is constructed from tetrahedrally coordinated Si atoms fused into an edge-shared octahedral plane of either Al(OH)3 or Mg(OH)2. The layers exhibit excellent mechanical properties parallel to the layer direction due to the nature of the bonding between these atoms. It has been found that Young’s modulus in the layer direction is 50 to 400 times higher than that of a typical polymer [1–5]. The layers have a high aspect ratio and each one is approximately 1 nm thick, while the diameter may vary from 30 nm to several microns or larger. Hundreds or thousands of these layers are stacked together with weak van der Waals forces to form a clay particle. With such a configuration, it is possible to tailor clays into various different structures in polymer [1,6,7].

An Investigation of the Creep of Ni3Al(B, Hf) Single Crystals at Intermediate Temperatures

1988 ◽  
Vol 133 ◽  
Author(s):  
K. J. Hemker ◽  
W. D. Nix
Keyword(s):  
Creep Deformation ◽  
Temperature Drop ◽  
Primary Creep ◽  
Constant Stress ◽  
Octahedral Plane ◽  
Creep Tests ◽  
Creep Properties ◽  
Yielding Behavior ◽  
Octahedral Slip ◽  
Inverse Creep

ABSTRACTThis study was undertaken to characterize the intermediate temperature creep properties of Ni3Al. Itfocuses on the mechanisms controlling creep deformation and their relationship to the anomalous yielding behavior of this alloy. Constant stress creep tests were conducted for temperatures between 713–973 K, and the following observations were made. The creep curves exhibited two distinct regions. Primary creep was followed by inverse creep. Specimens cooled under constant stress strained an additional 20% during cooling. Temperature drop experiments indicate that Ni3Al is weakened by the addition of creep deformation.Glide on the primary octahedral plane appears to be exhausted during primary creep. Slip trace and TEM studies indicate that inverse creep is controlled by slip on the cube cross slip plane and a secondary octahedral plane. Primary octahedral slip is observed in the specimens that are cooled and deformed under constant stress.

An Advanced Cap Model for Soil

2003 ◽  
Author(s):  
C. S. Tsai ◽  
Ching-Shyang Chen ◽  
Zhen-Yu Zhang ◽  
Bo-Jen Chen ◽  
J. C. Chen
Keyword(s):  
Failure Surface ◽  
Material Behavior ◽  
Constitutive Law ◽  
Octahedral Plane ◽  
Sensitive Material ◽  
Stress Strain ◽  
Stress Strain Relation ◽  
Highly Nonlinear ◽  
Cap Model ◽  
Strain Relationship

Soil, which is a pressure-sensitive material, is frequently encountered in the engineering profession. To ensure the safety of super-structures, it is prerequisite to fully understand the mechanical behavior of soil. The stress-strain relation of soil is highly nonlinear and complex. Therefore, problems involving soil need an appropriate constitutive model to describe its stress-strain relationship. This paper presents a new cap-type constitutive law for soil. The model is prominent in the sense that it satisfies the compatibility between the failure surface and the yield cap. It has modified the classical cap model to obtain smooth yield surfaces. In addition, the model effectively describes strength variations along various directions on the octahedral plane. The model has shown to realistically simulate soil responses in experiments by 7 parameters. The proposed concept can also be extended to include as many previous models published in the past for describing various observed material behavior as it is required.

Critical Plane Fatigue Modeling and Characterization of Single Crystal Nickel Superalloys

2004 ◽  
Vol 126 (2) ◽  
pp. 391-400 ◽  
Author(s):  
Rajiv A. Naik ◽  
Daniel P. DeLuca ◽  
Dilip M. Shah
Keyword(s):  
Single Crystal ◽  
Fatigue Damage ◽  
Crystal Orientation ◽  
Fatigue Crack Initiation ◽  
Fatigue Loading ◽  
Octahedral Plane ◽  
Slip Systems ◽  
Critical Plane ◽  
Damage Initiation ◽  
Fatigue Modeling

Single crystal nickel-base superalloys deform by shearing along 〈111〉 planes, sometimes referred to as “octahedral” slip planes. Under fatigue loading, cyclic stress produces alternating slip reversals on the critical slip systems which eventually results in fatigue crack initiation along the “critical” octahedral planes. A “critical plane” fatigue modeling approach was developed in the present study to analyze high cycle fatigue (HCF) failures in single crystal materials. This approach accounted for the effects of crystal orientation and the micromechanics of the deformation and slip mechanisms observed in single crystal materials. Three-dimensional stress and strain transformation equations were developed to determine stresses and strains along the crystallographic octahedral planes and corresponding slip systems. These stresses and strains were then used to calculate several multiaxial critical plane parameters to determine the amount of fatigue damage and also the “critical planes” along which HCF failures would initiate. The computed fatigue damage parameters were used along with experimentally measured fatigue lives, at 1100°F, to correlate the data for different loading orientations. Microscopic observations of the fracture surfaces were used to determine the actual octahedral plane (or facet) on which fatigue initiation occurred. X-ray diffraction measurements were then used to uniquely identify this damage initiation facet with respect to the crystal orientation in each specimen. These experimentally determined HCF initiation planes were compared with the analytically predicted “critical planes.”

Critical Plane Fatigue Modeling and Characterization of Single Crystal Nickel Superalloys

2002 ◽  
Author(s):  
Rajiv A. Naik ◽  
Daniel P. DeLuca ◽  
Dilip M. Shah
Keyword(s):  
Single Crystal ◽  
Fatigue Damage ◽  
Crystal Orientation ◽  
Fatigue Crack Initiation ◽  
Fatigue Loading ◽  
Octahedral Plane ◽  
Slip Systems ◽  
Critical Plane ◽  
Damage Initiation ◽  
Fatigue Modeling

Single crystal nickel-base superalloys deform by shearing along <111> planes, sometimes referred to as “octahedral” slip planes. Under fatigue loading, cyclic stress produces alternating slip reversals on the critical slip systems which eventually results in fatigue crack initiation along the ‘critical’ octahedral planes. A ‘critical plane’ fatigue modeling approach was developed in the present study to analyze high cycle fatigue (HCF) failures in single crystal materials. This approach accounted for the effects of crystal orientation and the micromechanics of the deformation and slip mechanisms observed in single crystal materials. Three-dimensional (3-D) stress and strain transformation equations were developed to determine stresses and strains along the crystallographic octahedral planes and corresponding slip systems. These stresses and strains were then used to calculate several multiaxial critical plane parameters to determine the amount of fatigue damage and also the ‘critical planes’ along which HCF failures would initiate. The computed fatigue damage parameters were used along with experimentally measured fatigue lives, at 1100° F, to correlate the data for different loading orientations. Microscopic observations of the fracture surfaces were used to determine the actual octahedral plane (or facet) on which fatigue initiation occurred. X-ray diffraction measurements were then used to uniquely identify this damage initiation facet with respect to the crystal orientation in each specimen. These experimentally determined HCF initiation planes were compared with the analytically predicted ‘critical planes’.

scholarly journals Synthesis, structure and properties of V(V) monooxido complex with ONO tridentate Schiff base

2019 ◽  
Vol 4 (1) ◽  
pp. 21-29 ◽  
Author(s):  
Anna Jurowska ◽  
Janusz Szklarzewicz ◽  
Maciej Hodorowicz ◽  
Ryszard Gryboś
Keyword(s):  
Schiff Base ◽  
Vertical Plane ◽  
Schiff Base Complex ◽  
Redox System ◽  
Irreversible Processes ◽  
Octahedral Plane ◽  
Structure And Properties ◽  
Vis Spectroscopy ◽  
Solvent Molecules ◽  
Tridentate Schiff Base

The oxidovanadium(V) Schiff base complex of formula [VO(L)(EtO)(EtOH)] (where H2L = Schiff base ligand derived from 5-methoxysalicylaldehyde and phenylacetic hydrazide) was synthesized and described. Complex crystalizes in triclinic P-1 space group. Octahedral geometry of the vanadium(V) centre is filed with oxido, ONO L2- ligand and two solvent molecules both in ethoxo and as neutral ethanol form. The complex is neutral, with 5- and 6-memebered ring formed by ONO ligand coordinated in octahedral plane with oxido and EtOH ligands in vertical positions. Two isomers are present in the unit cell, with different position of 5-membered ring versus vertical plane. The elemental analysis, magnetic susceptibility, thermogravimetry and spectroscopy (IR, UV-Vis) measurements were measured and are discussed. The cyclic voltammetry measurements show irreversible processes for vanadium(IV/V) redox system. Thermal stability both in a solid state (TG and SDTA measurements) as well as in solutions (at pH 7.0 and 2.0, studied by UV-Vis spectroscopy) is discussed.

Mechanical Loss Associated with Stress Anomaly in Ni3Al and Ni3(Al, Ta) Single Crystals

1999 ◽  
Vol 578 ◽  
Author(s):  
E. Carreno-Morelli ◽  
B.L. Cheng ◽  
M. Demura ◽  
R. Schaller ◽  
N. Baluc ◽  
...  
Keyword(s):  
Single Crystals ◽  
Oscillation Amplitude ◽  
Relaxation Peak ◽  
Octahedral Plane ◽  
Mechanical Loss ◽  
Positive Dependence ◽  
Thermally Activated ◽  
Temperature Regimes ◽  
Two Temperature ◽  
Thermally Activated Process

AbstractThe mechanical loss and shear modulus behaviors of Ni3Al and Ni3(Al, Ta) single crystals have been investigated in the temperature range 100 K – 1300 K. The mechanical loss spectra exhibit two temperature regimes, which are separated by a relaxation peak at nearly 950 K for a frequency of 1 Hz. This relaxation peak has been interpreted by the stress re-orientation of Al-Al elastic dipoles in the (111) octahedral plane [1, 2]. In the low temperature regime, corresponding to the anomaly domain of the flow stress, the mechanical loss of pre-deformed specimens exhibit a strong positive dependence on both the oscillation amplitude and the amount of pre-strain.Pre-deformations, which were performed either at room temperature or at 100 K, yield a broad maximum in the mechanical loss that extends from nearly 100 K up to 550 K. This maximum is observable for only strain amplitudes larger than 10−4 and entirely vanishes after heating the specimens above 550 K. The increase in mechanical loss has been attributed to the bowing of the superkinks under the action of the applied stress. The gradual and irreversible decrease in damping above 300 K is interpreted in terms of pinning of the screw dislocation segments by a thermally activated process leading to the formation of Kear-Wilsdorf locks.

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