Plastic Deformations in Single Crystals of FePd with the L10 Structure

2008 ◽  
Vol 1128 ◽  
Author(s):  
Katsushi Tanaka ◽  
Wang Chen ◽  
Kyosuke Kishida ◽  
Norihiko L. Okamoto ◽  
Haruyuki Inui
Keyword(s):  
Plastic Deformation ◽  
Shear Stress ◽  
Temperature Dependence ◽  
Single Crystals ◽  
Yield Stress ◽  
Room Temperature ◽  
Positive Temperature ◽  
Plastic Deformations ◽  
L10 Structure ◽  
Critical Resolved Shear Stress

AbstractCompressive deformations of L10-ordered single crystals of FePd have been investigated from room temperature to 873 K. The critical resolved shear stress for superlattice dislocations is hard to determine resulting from buckling that occurs after a small amount of conventional plastic deformation. The CRSS for superlattice dislocations determined from yield stress is significantly larger than that of ordinary dislocations. The CRSS for octahedral glide of ordinary and superlattice dislocations are virtually independent of the temperature, and the positive temperature dependence of the yield stress is not observed for both, ordinary and superlattice dislocations, by the present experiments.

Plastic Deformations in L10-Ordered Single Crystals with their c/a Ratios Less than Unity

2007 ◽  
Vol 561-565 ◽  
pp. 459-462
Author(s):  
Katsushi Tanaka ◽  
Hiromitsu Ide ◽  
Yoshinori Sumi ◽  
Kyosuke Kishida ◽  
Haruyuki Inui
Keyword(s):  
Shear Stress ◽  
Temperature Dependence ◽  
Single Crystals ◽  
Room Temperature ◽  
The Other ◽  
Compressive Deformation ◽  
Positive Temperature ◽  
Plastic Deformations ◽  
Temperature Range ◽  
Critical Resolved Shear Stress

Compressive deformation of L10-ordered single crystals of FePd whose c/a ratio less than unity have been investigated from room temperature to 823 K. The results show that the critical resolved shear stress (CRSS) for octahedral glide of ordinary dislocations is smaller than that of super-lattice dislocations in all the temperature range investigated, that is the opposite sense to the case of Ti-56 mol% Al. The CRSS for ordinary dislocations virtually independent to the temperature. On the other hand, the CRSS for super dislocations exhibits a weak positive temperature dependence from room temperature up to 573 K and decreases in higher temperatures.

Deformation and its Structure in Llo Ti-Al-Nb Compound Alloys

1988 ◽  
Vol 133 ◽  
Author(s):  
Yoo-Dong Hahn ◽  
Sung H. Whang
Keyword(s):  
Temperature Dependence ◽  
Yield Stress ◽  
Uniaxial Compression ◽  
High Temperatures ◽  
Room Temperature ◽  
Fracture Strain ◽  
Positive Temperature ◽  
Deformation Structures ◽  
Miniature Specimens ◽  
Deformation Tests

ABSTRACTThe ternary TiAl-Nb (Llo) alloys stabilized at 1000°C for a week were prepared into miniature specimens for compressive deformation tests. The specimens were deformed in uniaxial compression at room temperature as well as various high temperatures. The yield stress and fracture strain were determined with respect to Nb concentration, and as a function of temperature to investigate positive temperature dependence.Dislocation structures and other deformation structures of the deformed alloys were studied by TEM.

Strain Rate Dependence of the Flow Stress and Work-Hardening of Single Crystals of NI3(Al,Hf)B

1994 ◽  
Vol 364 ◽  
Author(s):  
S. S. Ezz ◽  
Y. Q. Sun ◽  
P. B. Hirsch
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Temperature Dependence ◽  
Single Crystals ◽  
Yield Stress ◽  
Strain Rate Sensitivity ◽  
Work Hardening ◽  
Room Temperature ◽  
Rate Sensitivity ◽  
Controlling Mechanism

AbstractThe strain rate sensitivity ß of the flow stress τ is associated with workhardening and β=(δτ/δln ε) is proportional to the workhardening increment τh = τ - τy, where τy is the strain rate independent yield stress. The temperature dependence of β/τh reflects changes in the rate controlling mechanism. At intermediate and high temperatures, the hardening correlates with the density of [101] dislocations on (010). The nature of the local obstacles at room temperature is not established.

Structure Characteristics of Cubic and Orthorhombic Phases of High Density Scintillator Pbf2 from 4.2–300 K

1994 ◽  
Vol 348 ◽  
Author(s):  
Ivan Shmyt'ko ◽  
I.B. Savchenko ◽  
N.V. Klassen ◽  
B.Sh. Bagautdinov ◽  
G.A. Emel'chenko ◽  
...  
Keyword(s):  
Phase Transition ◽  
Plastic Deformation ◽  
Temperature Dependence ◽  
Single Crystals ◽  
Room Temperature ◽  
Cell Parameter ◽  
Structure Characteristics ◽  
Pseudocubic Phase ◽  
Bulk Single Crystals ◽  
Structural Aspects

ABSTRACTAn anomaly of the temperature dependence of the unit cell parameter has been observed for β–PbF2 single crystals at 200 K that is interpreted as a phase transition to a pseudocubic lattice. Such a pseudocubic phase is observable at room temperature after uniaxial plastic deformation of the bulk single crystals. The structural aspects of the β→α transition have been established. The as-grown crystals of α–PbF2 phase are shown to undergo a phase transition at 100 K.

Room Temperature Deformation in “Soft” Orientation Nial Single Crystals

1990 ◽  
Vol 213 ◽  
Author(s):  
R.D. Field ◽  
D.F. Lahrman ◽  
R. Darolia
Keyword(s):  
Shear Stress ◽  
Elevated Temperature ◽  
Single Crystals ◽  
Room Temperature ◽  
Dislocation Motion ◽  
Temperature Deformation ◽  
Slip Planes ◽  
Schmid Factor ◽  
Critical Resolved Shear Stress ◽  
Active Slip

ABSTRACTA detailed study of deformation of NiAl single crystals in two soft orientations, <110> and <111>, has been conducted. The Schmid factor favors {100} slip in the former and {110} slip in the latter. Detailed dislocation analysis, critical resolved shear stress measurements, and slip trace analysis have been performed to determine the nature of dislocation motion and interactions in this material. Particular attention is given to prismatic loops formed during deformation, since the shapes of these loops reveal the active slip planes. Similar loop morphologies observed in elevated temperature [001] oriented tensile specimens are also discussed.

Characteristics of Ordinary ½⟨110] Slip in Single Crystals of γ-TiAl

1998 ◽  
Vol 552 ◽  
Author(s):  
S. Jiao ◽  
N. Bird ◽  
P. B. Hirsch ◽  
G. Taylor
Keyword(s):  
Shear Stress ◽  
Single Crystals ◽  
Yield Stress ◽  
Dislocation Slip ◽  
Slip Systems ◽  
Different Temperatures ◽  
Critical Resolved Shear Stress ◽  
Thermal Reversibility ◽  
Edge Dislocations

ABSTRACTA study of the occurrence of ordinary slip in single crystals of Ti 54.5 at% Al with various orientations at different temperatures shows that the critical resolved shear stress is approximately the same for ¼⟨110] slip on {111} and {110} planes near the peak of the yield stress anomaly. However the shapes of the glide loops are quite different, suggesting that the order of relative mobilities of screw and edge dislocations is reversed in the two cases. The reason for this and its possible effect on the mechanism responsible for the yield stress anomaly of ½⟨110] {111} slip are discussed. Experiments on the thermal reversibility of the yield stress when either ordinary- or super- dislocation slip systems are operating at both temperatures have shown that the yield stress is reversible for the latter but not reversible in the former case.

Effects of Alloying Elements on the Temperature Dependence of Yield Stress in L12-Co3(Al,W)

2015 ◽  
Vol 1760 ◽  
Author(s):  
Zhenghao M. T. Chin ◽  
Norihiko L. Okamoto ◽  
Haruyuki Inui
Keyword(s):  
High Temperature ◽  
Temperature Dependence ◽  
Yield Stress ◽  
Room Temperature ◽  
Single Phase ◽  
Alloying Elements ◽  
High Temperature Strength ◽  
Positive Temperature ◽  
Compression Tests ◽  
Polycrystalline Alloys

ABSTRACTThe effects of alloying elements (Ni/Ta) on the temperature dependence of yield stress in Co3(Al,W) with the L12 structure have been investigated through compression tests of nearly single-phase polycrystalline alloys in the temperature range between room temperature to 1,473K. Compared with a ternary Co3(Al,W), a Ni/Ta-added Co3(Al,W) alloy exhibits a higher γ΄ solvus temperature and lower onset temperature of the yield stress anomaly (positive temperature dependence of yield stress), suggesting that the CSF energy is increased by Ni/Ta addition. As a consequence, the high-temperature strength in Co3(Al,W) is considerably enhanced.

Plastic Deformation of Ni3Nb Single Crystals

1998 ◽  
Vol 552 ◽  
Author(s):  
Kouji Hagihara ◽  
Takayoshi Nakano ◽  
Yukichi Umakoshi
Keyword(s):  
Plastic Deformation ◽  
Shear Stress ◽  
Single Crystals ◽  
Crystal Orientation ◽  
Strengthening Mechanism ◽  
Orientation Dependence ◽  
Slip Model ◽  
Compression Tests ◽  
Increasing Temperature ◽  
Critical Resolved Shear Stress

ABSTRACTTemperature dependence of yield stress and operative slip system in Ni3Nb single crystals with the DOa structure was investigated in comparison with that in an analogous L12 structure. Compression tests were performed at temperatures between 20 °C and 1200 °C for specimens with loading axes perpendicular to (110), (331) and (270).(010)[100] slip was operative for three orientations, while (010)[001] slip for (331) and {211} <10 7 13> twin for (270) orientations were observed, depending on deformation temperature. The critical resolved shear stress (CRSS) for the (010)[100] slip anomaly increased with increasing temperature showing a maximum peak between 400 °C and 800 °C depending on crystal orientation. The CRSS showed orientation dependence and no significant strain rate dependence in the temperature range for anomalous strengthening. The [100] dislocations with a screw character were aligned on the straight when the anomalous strengthening occurred. The anomalous strengthening mechanism for (010)[100] slip in Ni3Nb single crystals is discussed on the basis of a cross slip model which has been widely accepted for some L12-type compounds.

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