scholarly journals Determining heterogeneous slip activity on multiple slip systems from single crystal orientation pole figures

2016 ◽  
Vol 116 ◽  
pp. 200-211 ◽  
Author(s):  
Darren C. Pagan ◽  
Matthew P. Miller
Keyword(s):  
Single Crystal ◽  
Crystal Orientation ◽  
Slip Systems ◽  
Multiple Slip ◽  
Slip Activity ◽  
Pole Figures

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.

scholarly journals Effect of Machining Velocity on the Crystallographic Textures in a Diamond Turned Aluminium Single Crystal

1999 ◽  
Vol 31 (4) ◽  
pp. 249-261 ◽  
Author(s):  
S. To ◽  
W.B. Lee ◽  
C.Y. Chan
Keyword(s):  
Single Crystal ◽  
High Speed ◽  
Electron Back Scatter Diffraction ◽  
Lattice Rotation ◽  
Slip Systems ◽  
Machined Surface ◽  
Bottom Part ◽  
Pole Figures ◽  
Deformed Layer ◽  
Cutting Velocity

The orientation changes in the crystallographic textures of a diamond turned aluminium single crystal have been investigated. The X-ray pole figures were collected at various locations on the surfaces turned at high speed. In the central part of the turned surfaces, the pole figures revealed the presence of a thin deformed layer. Four sets of slip systems were found to operate to a very similar extent. However, as the distance from the centre increased, the operation of these four sets of slip systems varied and the textural changes were found to be increasingly affected by the cutting velocity. In a separate grooving experiment, electron back-scatter diffraction (EBSD) patterns were collected at various locations along the bottom part of the groove. These patterns revealed a lattice rotation on the machined surface which was induced by shearing along the cutting direction.

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.

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’.

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.

Dislocation Substructures Produced During Tensile, Creep, and Fatigue Deformation of Ti3Al at 700°C

1977 ◽  
Vol 35 ◽  
pp. 272-273
Author(s):  
S. M. L. Sastry
Keyword(s):  
Intermetallic Compound ◽  
Strain Rate ◽  
Tensile Creep ◽  
Slip Systems ◽  
Slip Vector ◽  
Superlattice Structure ◽  
Slip Activity ◽  
Dislocation Arrangement ◽  
Ordered Intermetallic ◽  
Tangled Dislocation

Ti3Al is an ordered intermetallic compound having the DO19-type superlattice structure. The compound exhibits very limited ductility in tension below 700°C because of a pronounced planarity of slip and the absence of a sufficient number of independent slip systems. Significant differences in slip behavior in the compound as a result of differences in strain rate and mode of deformation are reported here.Figure 1 is a comparison of dislocation substructures in polycrystalline Ti3Al specimens deformed in tension, creep, and fatigue. Slip activity on both the basal and prism planes is observed for each mode of deformation. The dominant slip vector in unidirectional deformation is the a-type (b) = <1120>) (Fig. la). The dislocations are straight, occur for the most part in a screw orientation, and are arranged in planar bands. In contrast, the dislocation distribution in specimens crept at 700°C (Fig. lb) is characterized by a much reduced planarity of slip, a tangled dislocation arrangement instead of planar bands, and an increased incidence of nonbasal slip vectors.

Effect of crystal orientation on droplet wetting behavior on single-crystal Al2O3 substrates: An experimental study

2020 ◽  
Vol 32 (12) ◽  
pp. 127110
Author(s):  
Chengyu He ◽  
Tie Liu ◽  
Lei Tian ◽  
Yubao Xiao ◽  
Shang Yuan ◽  
...  
Keyword(s):  
Experimental Study ◽  
Single Crystal ◽  
Crystal Orientation ◽  
Wetting Behavior

scholarly journals Estimation of 8th, 10th and 12th Order ODF Coefficients From Elastic Properties in Cold Rolled Steel Sheets by Adjustment of Single Crystal Elastic Constants

1990 ◽  
Vol 12 (1-3) ◽  
pp. 175-185 ◽  
Author(s):  
Kei Sakata ◽  
Dominique Daniel ◽  
John J. Jonas
Keyword(s):  
Single Crystal ◽  
Elastic Constants ◽  
Elastic Energy ◽  
X Rays ◽  
Rolled Steel ◽  
Steel Sheets ◽  
Fitting Procedure ◽  
Pole Figures ◽  
Cold Rolled ◽  
Fiber Components

In an earlier paper (Sakata et al., 1989), it was shown that the 4th and 6th order ODF coefficients could be successfully derived from Young's modulus measurements using the elastic energy method. However, the values of some of the coefficients fell beyond the expected error ranges. In this study, more appropriate single crystal elastic constants are selected by means of a fitting procedure. Then the ODF coefficients are again estimated in the manner described previously. As a result, the values of the C411, C611, C612 and C614 coeffioents, which were somewhat inaccurate in the previous calculation, are improved considerably. The volume fractions of the principal preferred orientations are then employed to predict the 8th order coefficients and the fiber components of the l = 10 and l = 12 (C1011, C1211 and C1221) coefficients. With the aid of the coefficients obtained in this way, both pole and inverse pole figures are drawn, which are in better agreement with those based on X-rays than when only the 4th order coefficients are employed.

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