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.

An In Situ Observation of Slip Deformation in a Compressed Ti-Mo-Al Single Crystal

2018 ◽  
Vol 941 ◽  
pp. 1463-1467
Author(s):  
Ryotaro Hara ◽  
Masaki Tahara ◽  
Tomonari Inamura ◽  
Hideki Hosoda
Keyword(s):  
Martensitic Transformation ◽  
Slip System ◽  
Single Crystal ◽  
Deformation Behavior ◽  
Room Temperature ◽  
Martensite Phase ◽  
Slip Direction ◽  
Β Phase ◽  
Slip Deformation

The stress-induced martensitic transformation and slip deformation behavior were investigated by the compression test with anin-situobservation in a Ti-6Mo-10Al (mol %) alloy single crystal. Owing to the stress-induced martensitic transformation from the parent β phase to the α′′ martensite phase, the single crystal of α′′ martensite without internal twinnings was successfully obtained at room temperature. By further compression, the slip deformation occurred in the single crystal of α′′ martensite. The operated slip system in the α′′ martensite was analyzed by the two face trace analyses, and the slip direction was determined to be []o.

The Slip Transfer Process Through Grain Boundaries in HCP Ti

1993 ◽  
Vol 319 ◽  
Author(s):  
J. Shirokoff ◽  
I.M. Robertson ◽  
H.K. Birnbaum
Keyword(s):  
Grain Boundary ◽  
Slip System ◽  
Grain Boundaries ◽  
Slip Systems ◽  
Boundary Dislocation ◽  
Burgers Vector ◽  
Slip Transfer ◽  
Transmission Electron ◽  
Fcc Materials

AbstractInformation on the mechanisms of slip transfer across grain boundaries in an HCP α-Ti alloy has been obtained from deformation experiments performed In situ in the transmission electron microscope. Initially, lattice dislocations are accommodated within the grain boundary until a critical local dislocation density is reached. The boundary then responds by activating slip in the adjoining grain on the slip system experiencing the highest local resolved shear stress and producing the residual grain-boundary dislocation with the smallest Burgers vector. Slip on secondary slip systems may be initiated provided they reduce the magnitude of the Burgers vector of, or eliminate, the residual grainboundary dislocation. The selection rules used to predict the slip system activated by the grain boundary are the same as apply in ordered and disordered FCC materials.

Dislocation Plasticity and Complementary Deformation Mechanisms in Polycrystalline Mg Alloys

2004 ◽  
Vol 449-452 ◽  
pp. 665-668 ◽  
Author(s):  
Junichi Koike
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Deformation Mechanism ◽  
Room Temperature ◽  
Grain Boundary Sliding ◽  
Mg Alloys ◽  
Deformation Mechanisms ◽  
Slip Systems ◽  
Dislocation Plasticity ◽  
Boundary Sliding

Deformation mechanisms of Mg-Al-Zn (AZ31) alloys were investigated by performing tensile test at room temperature. In fine grain Mg alloys deformed at room temperature, nonbasal slip systems were found to be active as well as basal slip systems because of grain-boundary compatibility effect. Slip-induced grain-boundary sliding occurred as a complementary deformation mechanism to give rise to c-axis component of strain. With increasing grain size, the activation of the nonbasal slip systems was limited near grain boundaries. Instead of grain-boundary sliding, twinning occurred as a complementary deformation mechanism in large grained samples. Orientation analysis of twins indicated that twinning is induced by stress concentration due to the pile up of basal dislocations. The grain-size dependence on deformation mechanism was found to affect yielding behavior both microscopically and macroscopically which can influence various mechanical properties such as fatigue and creep.

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.

Radiation-Induced Conformation Changes of the Pyrimidine Ring in a Single Crystal of Dihydrothymine

1970 ◽  
Vol 25 (8-9) ◽  
pp. 1299-1302 ◽  
Author(s):  
J. N. Herak
Keyword(s):  
Single Crystal ◽  
Room Temperature ◽  
Pyrimidine Ring ◽  
Orientation Dependence ◽  
Ordered Structure ◽  
Radical Species ◽  
Conformation Changes ◽  
Radiation Induced ◽  
Hyperfine Couplings

Abstract Radiation-induced radicals in a single crystal of dihydrothymine were studied with EPR. It was found that the 5-thymyl radical is the dominant radical species at room temperature. The orientation dependence of the hyperfine couplings can only by explained if one assumes that C(5), C(6) and C(7) lie in the plane defined by the rest of the nonhydrogen atoms of the ring. The highly dis-ordered structure of the ring in the undamaged crystal is ordered if a proton bound to C(5) is removed.

Thermal conductivity of AlN ceramic with a very low amount of grain boundary phase at 4 to 1000 K

2002 ◽  
Vol 17 (11) ◽  
pp. 2940-2944 ◽  
Author(s):  
Koji Watari ◽  
Hiromi Nakano ◽  
Kazuyori Urabe ◽  
Kozo Ishizaki ◽  
Shixun Cao ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Grain Boundary ◽  
Single Crystal ◽  
Room Temperature ◽  
Phonon Scattering ◽  
Amorphous Film ◽  
Boundary Phase ◽  
Temperature Conductivity ◽  
Room Temperature Conductivity ◽  
Significant Difference

An AlN ceramic fired at 2173 K for 100 h under a reduced N2 atmosphere with carbon possessed a room-temperature conductivity of 272 Wm−1K−1, slightly lower than the value for high-purity, single-crystal AlN. However, the thermal conductivity of the ceramic at temperatures below 100 K was much lower than that of single crystal. This is mainly due to phonon scattering by grain junctions that possess an amorphous film with a thickness of under 1 nm. At 500 to 1000 K, no significant difference in the conductivity was observed between the ceramic and the single crystal.

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.

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.

scholarly journals Ca-induced Plasticity in Magnesium Alloy: EBSD Measurements and VPSC Calculations

Crystals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 67 ◽  
Author(s):  
Umer Masood Chaudry ◽  
Kotiba Hamad ◽  
Jung-Gu Kim
Keyword(s):  
Shear Stress ◽  
Magnesium Alloy ◽  
Slip System ◽  
Basal Slip ◽  
Room Temperature ◽  
Prismatic Slip ◽  
Slip Systems ◽  
Electron Backscattered Diffraction ◽  
Self Consistent ◽  
Critical Resolved Shear Stress

In the present work, Ca-induced plasticity of AZ31 magnesium alloy was studied using electron backscattered diffraction (EBSD) measurements supported by viscoplastic self-consistent (VPSC) calculations. For this purpose, alloy samples were stretched to various strains (5%, 10%, and 15%) at room temperature and a strain rate of 10−3 s−1. The EBSD measurements showed a higher activity of non-basal slip system (prismatic slip) as compared to that of tension twins. The VPSC confirmed the EBSD results, where it was found that the critical resolved shear stress of the various slip systems and their corresponding activities changed during the stretching of the alloy samples.

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