Investigation of Operative Slip System in β-Sn Single Crystal and the Relation between the Crystal Orientation and the Slip Systems

1993 ◽  
Vol 32 (Part 1, No. 7) ◽  
pp. 3214-3216 ◽  
Author(s):  
Bahattin Düzgün ◽  
Işik Aytaş
Keyword(s):  
Slip System ◽  
Single Crystal ◽  
Crystal Orientation ◽  
Slip Systems

scholarly journals Effect of secondary crystal orientations on the deformation anisotropy for nickel-based single-crystal plate with notch feature

2019 ◽  
Vol 54 (1) ◽  
pp. 54-64 ◽  
Author(s):  
Yu Zhai ◽  
Muhammad Kashif Khan ◽  
José Correia ◽  
Abílio MP de Jesus ◽  
Zhiyong Huang ◽  
...  
Keyword(s):  
Single Crystal ◽  
Deformation Process ◽  
Crystal Orientation ◽  
Turbine Blades ◽  
Von Mises Stress ◽  
Slip Systems ◽  
Nickel Based Superalloy ◽  
Crystal Orientations ◽  
Single Crystal Plate ◽  
Von Mises

The effects of the secondary crystal orientations on the nickel-based single-crystal superalloy turbine blades were investigated. The stress concentration features were used for investigation of the optimal secondary crystal orientation leading to the higher strength of the single-crystal turbine blades. The crystal plastic finite element method coupled with micromechanics constitutive model is applied to study the effect of secondary crystal orientation on plastic deformation and mechanical behavior around the cooling holes and notches with the primary (load) orientation fixed at [001] direction. For nickel-based superalloy plates with holes or notches, the secondary crystal orientation effect on the strength needs to be clarified at various load levels. The maximum von Mises stress in the single-crystal alloy varies significantly with variation in the secondary crystal orientations. It was found that only two slip systems dominate the deformation process of the material owing to their favorable orientation with loading. The secondary orientation of 45° was identified with lowest resolved shear stress in the dominating slip systems and potential of producing higher strength for single-crystal turbine blades.

Dislocation Boundaries and Slip Systems in Uniaxially Deformed Crystals

2001 ◽  
Vol 683 ◽  
Author(s):  
Grethe Winther ◽  
Xiaoxu Huang ◽  
Søren Fæster Nielsen ◽  
John Wert
Keyword(s):  
Single Crystal ◽  
Single Crystals ◽  
Crystal Orientation ◽  
Boundary Plane ◽  
Slip Systems ◽  
Crystal Boundary ◽  
Secondary Slip ◽  
Slip Planes ◽  
Planar Dislocation ◽  
Active Slip

ABSTRACTThe dislocations in the extended planar dislocation boundaries formed during deformation are generated by the active slip systems. Investigation of the boundaries is therefore a tool to obtain information on the active slip systems. Here, the orientation of the dislocation boundaries in uniaxially deformed aluminum poly- and single crystals are compared. It is found that the single crystal boundary planes are consistent with those found in polycrystals, indicating that the active slip systems in single and polycrystals are the same. However, boundaries are closer to the slip planes in the single crystals. This is taken as an indication that the secondary slip systems are more active in the polycrystal. The orientation of the boundary plane varies with the crystal orientation in a way that is consistent with activation of the five most stressed slip systems.

Crystallographic Constitutive Models for Single Crystal Superalloys

2011 ◽  
Vol 197-198 ◽  
pp. 1381-1388 ◽  
Author(s):  
Qing Wu Wang ◽  
Mao Pang ◽  
Shi Hui Zhang
Keyword(s):  
Slip System ◽  
Single Crystal ◽  
Mechanical Response ◽  
Constitutive Models ◽  
Slip Systems ◽  
Flow Equations ◽  
Hardening Law ◽  
Crystallographic Slip ◽  
Set Up ◽  
Octahedral Slip

Single crystal nickel base superalloys, such as Chinese material DD6 have been used in gas turbine blade in China more and more widely. In order to make better use of single crystal superalloys with many excellencies, constitutive models have been developed. In this paper, general method of crystallographic constitutive modeling was summarizes and a new constitutive model, based on crystallographic theory was proposed with phenomenological models' advantages. Based on crystallographic slip system principle, the basic slip-based viscoplasticity theory equations were set up on 12 octahedral slip systems and 6 cubic slip systems, total 18 slip systems. In micro-level slip system, the general unified constitutive formulations were used as the flow equations and hardening law. In the model, scalar forms were applied for constitutive equations on slip systems and the number and types of active slip systems were used to describe the material anisotropy, which was satisfied automatically by slip systems not anisotropic tensors and. The experimental and calculation results of two kind single crystal superalloys PWA1480 and DD6 were compared. The model had the capability to predict many mechanical response and analyze structure of single crystal superalloys. The modeling procedures and results showed that this crystallographic model had more clear physical meaning and was exact.

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’.

Influence of Grain Boundary on Activation of Slip Systems in Magnesium: Crystal Plasticity Analysis

2010 ◽  
Vol 654-656 ◽  
pp. 695-698 ◽  
Author(s):  
Tsuyoshi Mayama ◽  
Tetsuya Ohashi ◽  
Kenji Higashida
Keyword(s):  
Grain Boundary ◽  
Slip System ◽  
Crystal Plasticity ◽  
Crystal Orientation ◽  
Basal Slip ◽  
Prismatic Slip ◽  
Shear Stresses ◽  
Slip Systems ◽  
Analysis Method ◽  
Pyramidal Slip

Crystal plasticity finite element analysis method considering the accumulation of geometrically necessary (GN) dislocations was applied to monotonic loading of pure magnesium bi-crystal. The deformation mechanisms considering in the present analysis method are basal slip <a>, prismatic slip <a>, 1st order pyramidal slip <a>, 2nd order pyramidal slip <a+c> and tensile twinning <a+c>. Tensile twinning is incorporated into crystal plasticity analysis assuming that twinning plane and direction of shear by twinning are equivalent to slip plane and slip direction, respectively. Critical resolved shear stresses (CRSSs) for each slip system in the literatures were used. Analysis model is designed to investigate the influence of grain boundary on the activation of slip systems. That is, one grain consisting of bi-crystal (grain A) had the crystal orientation whose Schmid factor for prismatic slip is 0.5. The crystal orientation of the other grain (grain B) was slightly deviated from that of grain A. The result of the calculation of tensile loading of the bi-crystal showed that both grains are deformed by the multiple slip of basal slip system, which resulted in the formation of GN dislocation bands.

scholarly journals Crystallographic Orientation Dependence of Mechanical Responses of FeCrAl Micropillars

Crystals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 943
Author(s):  
Dongyue Xie ◽  
Binqiang Wei ◽  
Wenqian Wu ◽  
Jian Wang
Keyword(s):  
Grain Boundary ◽  
Slip System ◽  
Single Crystal ◽  
Room Temperature ◽  
Orientation Dependence ◽  
Slip Systems ◽  
Flow Strength ◽  
Mechanical Responses ◽  
Fecral Alloy ◽  
Strain Hardening Rate

Iron-chromium-aluminum (FeCrAl) alloys are used in automobile exhaust gas purifying systems and nuclear reactors due to its superior high-temperature oxidation and excellent corrosion resistance. Single-phase FeCrAl alloys with a body centered cubic structure plastically deform through dislocation slips at room temperature. Here, we investigated the orientation dependence of mechanical responses of FeCrAl alloy through testing single-crystal and bi-crystal micropillars in a scanning electron microscopy at room temperature. Single-crystal micropillars were fabricated with specific orientations which favor the activity of single slip system or two slip systems or multiple slip systems. The strain hardening rate and flow strength increase with increasing the number of activated slip system in micropillars. Bi-crystal micropillars with respect to the continuity of slip systems across grain boundary were fabricated to study the effect of grain boundary on slip transmission. The high geometrical compatibility factor corresponds to a high flow strength and strain hardening rate. Experimental results provide insight into understanding mechanical response of FeCrAl alloy and developing the mechanisms-based constitutive laws for FeCrAl polycrystalline aggregates.

Slip systems and critical resolved shear stress in pyrite: an electron backscatter diffraction (EBSD) investigation

2008 ◽  
Vol 72 (6) ◽  
pp. 1181-1199 ◽  
Author(s):  
C. D. Barrie ◽  
A. P. Boyle ◽  
S. F. Cox ◽  
D. J. Prior
Keyword(s):  
Shear Stress ◽  
Slip System ◽  
Single Crystal ◽  
Electron Backscatter Diffraction ◽  
Lattice Rotation ◽  
Slip Systems ◽  
Boundary Trace ◽  
Electron Backscatter ◽  
Backscatter Diffraction ◽  
Critical Resolved Shear Stress

AbstractA suite of experimentally deformed single-crystal pyrite samples has been investigated using electron backscatter diffraction (EBSD). Single crystals were loaded parallel to <100> or <110> and deformed at a strain rate of 10-5s-1, confining pressure of 300 MPa and temperatures of 600°C and 700°C. Although geometrically (Schmid factor) the {001}<100> slip system should not be activated in <100> loaded samples, lattice rotation and boundary trace analyses of the distorted crystals indicate this slip system is easier to justify. Determination of 75 MPa as the critical resolved shear stress (CRSS) for {001}<100> activation, in the <110> loaded crystals, suggests a crystal misalignment of ~5—15° in the <100> loaded crystals would be sufficient to activate the {001}<100> slip system. Therefore, {001}<100> is considered the dominant slip system in all of the single-crystal pyrite samples studied. Slip-system analysis of the experimentally deformed polycrystalline pyrite aggregates is consistent with the single-crystal findings, with the exception that {001}<11̄> also appears to be important, although less common than the {001}<100> slip system. The lack of crystal preferred orientation (CPO) development in the polycrystalline pyrite aggregates can be accounted for by the presence of two independent symmetrically equivalent slip systems more than satisfying the von Mises criterion.

Electron Microscopy of Shock Loaded Polycrystalline Beryllium

1974 ◽  
Vol 32 ◽  
pp. 506-507 ◽  
Author(s):  
J. M. Galbraith ◽  
L. E. Murr ◽  
A. L. Stevens
Keyword(s):  
Electron Microscopy ◽  
Wave Propagation ◽  
Structural Change ◽  
Single Crystal ◽  
Diffraction Pattern ◽  
Shock Loading ◽  
Slip Systems ◽  
Compression Tests ◽  
X Ray Diffraction ◽  
X Ray

Uniaxial compression tests and hydrostatic tests at pressures up to 27 kbars have been performed to determine operating slip systems in single crystal and polycrystal1ine beryllium. A recent study has been made of wave propagation in single crystal beryllium by shock loading to selectively activate various slip systems, and this has been followed by a study of wave propagation and spallation in textured, polycrystal1ine beryllium. An alteration in the X-ray diffraction pattern has been noted after shock loading, but this alteration has not yet been correlated with any structural change occurring during shock loading of polycrystal1ine beryllium.This study is being conducted in an effort to characterize the effects of shock loading on textured, polycrystal1ine beryllium. Samples were fabricated from a billet of Kawecki-Berylco hot pressed HP-10 beryllium.

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