Deformation Behavior of NiAl-Based Alloys Containing Iron, Cobalt, and Hafnium

1988 ◽  
Vol 133 ◽  
Author(s):  
D. R. Pank ◽  
M. V. Nathal ◽  
D. A. Koss
Keyword(s):  
Yield Stress ◽  
Deformation Behavior ◽  
Single Phase ◽  
Flow Behavior ◽  
Iron Cobalt ◽  
Alloying Additions ◽  
Compressive Flow ◽  
Melt Spun ◽  
Increasing Temperature

ABSTRACTThe effects of alloying additions on the mechanical properties of the B2 intermetallic NiAl have been investigated in both the melt-spun ribbon and consolidated, bulk form. The study is based on a matrix of NiAl-based alloys with up to 20 a/o Co and Fe additions and with reduced Al levels in the range of 30 – 40 a/o. Characterization of the melt-spun ribbon by optical and scanning electron microscopy indicates a range of microstructures: single phase β γ, necklace phase surrounding either martensitic or β grains, and a mixture of equiaxed martensitic and γ grains. Bend ductility is present in melt-spun and annealed ribbons exhibiting the γ necklace structure and in a single phase β material containing 20 a/o Fe.The analysis of compressive flow behavior on consolidated, bulk specimens indicates that the single phase γ alloys exhibit a continuous decrease in yield stress with increasing temperature and profuse microcracking at grain boundaries. In contrast, multiphase (γ + either martensite or β) alloys tend to display a peak in flow stress between 600 and 800K with little or no signs of microcracking. In general, heat treatments which convert the martensitic grains to β + γ result in improved strength at temperatures above 600K and better resistance to crack initiation. These results are discussed in terms of the effects of β, martensite and γ on the yield stress and flow behavior of NiAl-based alloys.

The High Temperature Deformation Behavior of A Cr2Nb Ordered Intermetallic System

1990 ◽  
Vol 213 ◽  
Author(s):  
G. E. Vignoul ◽  
J.M. Sanchez ◽  
J. K. Tien
Keyword(s):  
Deformation Behavior ◽  
Elevated Temperatures ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Deformation Law ◽  
Ordered Intermetallic ◽  
Intermetallic System ◽  
Increasing Temperature ◽  
Stress Term

ABSTRACTA basic characterization of the deformation behavior of Cr2Nb by microindention at ambient and elevated temperatures (up to 1400 °C) was undertaken. The microhardness of this system was seen to decrease with increasing temperature, from 1040 MPa at 25°C to 322 MPa at 1400 °C. Further, the microindention creep behavior of this system was studied by varying time on load at T = 1000 and 1200°C. Analysis of the data showed that m = 24 and Qapp = 477.61 kJ/mole. These unusually high values are indicative of the existence of an effective resisting stress against creep. When the data was fit against a microindention creep deformation law which was modified to incorporate an effective resisting stress term, it was determined that m = 4.5, Qcreep = 357 kJ/mole and the resisting stress term σr = 300 MPa.

Plane Strain Compression of Single Crystalline Ni3Al-Base Intermetallic Compounds

2005 ◽  
Vol 495-497 ◽  
pp. 767-774
Author(s):  
S.H. Song ◽  
Kyosuke Kishida ◽  
Masahiko Demura ◽  
Myung Hoon Oh ◽  
Dang Moon Wee ◽  
...  
Keyword(s):  
Intermetallic Compounds ◽  
Plane Strain ◽  
Deformation Behavior ◽  
Single Phase ◽  
Flow Behavior ◽  
Plane Strain Compression ◽  
Compression Tests ◽  
Two Phase ◽  
Single Crystalline ◽  
The Difference

Anisotropic deformation behavior of single crystalline Ni3Al-base intermetallic compounds, including Ni3Al single-phase and Ni/Ni3Al two-phase alloys, was systematically studied by the plane strain compression tests. Plastic flow behavior of single phase Ni3Al is strongly dependent on the initial crystal orientation and the flow stress becomes higher with increasing the numbers of the operative slip planes. In the case of the Ni/Ni3Al two phase alloys, the flow behavior is found to be divided into two stages. Such flow behavior is considered to be closely related to the difference in the deformation behavior between Ni solid solution and Ni3Al precipitates.

Dislocation Core Structure and the Normal Yield Behavior of L12 Ordered Alloys

1984 ◽  
Vol 39 ◽  
Author(s):  
G. Tichy ◽  
V. Vitek ◽  
D. P. Pope
Keyword(s):  
Yield Stress ◽  
High Temperatures ◽  
Flow Behavior ◽  
Dislocation Core ◽  
Screw Dislocations ◽  
Thermally Activated ◽  
Normal Behavior ◽  
Ordered Alloys ◽  
Increasing Temperature ◽  
Good Agreement

ABSTRACTA rapid increase of the yield stress with increasing temperature, often observed in L12 ordered alloys, is commonly called the “anomalous flow behavior”. This phenomenon is believed to result from the thermally activated transformation of the core of 1/2<110> screw dislocations from a glissile form to a sessile form at high temperatures. It is shown here that another class of L12 alloys exists in which these two forms of the screw dislocation core are not available. These are the alloys in which the APB on {111} planes is not stable and the atomistic studies of screw dislocations in such alloys show that their cores are always sessile. The yield stress of these alloys then increases with decreasing temperature and no increase at high temperatures occurs. Such behavior has been observed, for example, in Pt3Al. This “normal” behavior is analogous to that of b.c.c. metals and a theory of the temperature dependence of the yield stress has been developed along the same lines as in the case of b.c.c. metals. Comparison of this theory with measurements on Pt3Al single crystals shows a good agreement.

scholarly journals Constitutive Descriptions and Restoration Mechanisms of a Fe-17Cr Alloy during Deformation at Temperatures of 700–1000 °C

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5022
Author(s):  
Fei Gao ◽  
Zilong Gao ◽  
Qiyong Zhu ◽  
Zhenyu Liu
Keyword(s):  
Shear Band ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
Flow Behavior ◽  
Peak Stress ◽  
Type Model ◽  
Hollomon Parameter ◽  
Transmission Electron ◽  
Precession Electron Diffraction ◽  
Increasing Temperature

The deformation behavior for highly purified Fe-17Cr alloy was investigated at 700~1000 °C and 0.5~10 s−1. The microstructure evolution and corresponding mechanism during deformation were studied in-depth, using electron backscattering diffraction, transmission electron microscopy and precession electron diffraction. During deformation, dynamic recrystallization (DRX) occurred, along with extensive dynamic recovery, and the active DRX mechanism depended on deformation conditions. At higher Zener-Hollomon parameter (Z ≥ 5.93 × 1027 s−1), the development of the shear band was promoted, and then continuous DRX was induced by the formation and intersection shear band. At lower Zener-Hollomon parameter (Z ≤ 3.10 × 1025 s−1), the nucleation of the new grain was attributed to the combination of continuous DRX by uniform increase in misorientation between subgrains and discontinuous DRX by grain boundary bulging, and with increasing temperature, the effect of the former became weaker, whereas the effect of the latter became stronger. The DRX grain size increased with the temperature. For alleviating ridging, it seems advantageous to activate the continuous DRX induced by shear band through hot deformation with higher Z. In addition, the modified Johnson-Cook and Arrhenius-type models by conventional way were developed, and the modified Johnson-Cook model was developed, using the proposed way, by considering strain dependency of the material parameters. The Arrhenius-type model was also modified by using the proposed way, through distinguishing stress levels for acquiring partial parameter and through employing peak stress to determine the activation energy and considering strain dependency of only other parameters for compensating strain. According to our comparative analyses, the modified Arrhenius-type model by the proposed approach, which is suggested to model hot-deformation behavior for metals having only ferrite, could offer a more accurate prediction of flow behavior as compared to other developed models.

Dislocation dissociation in Ll2 ordered alloy Ni3Ge

1994 ◽  
Vol 52 ◽  
pp. 688-689
Author(s):  
J. Fang ◽  
E. M. Schulson ◽  
I. Baker
Keyword(s):  
Yield Stress ◽  
Room Temperature ◽  
Complete Analysis ◽  
Deformation Structure ◽  
Burgers Vector ◽  
Tem Characterization ◽  
Perfect Dislocation ◽  
Increasing Temperature ◽  
Dislocation Dissociation

It is well established that the yield stress of Ni3Ge anomalously increases with increasing temperature from 77 K to 673 K. Above room temperature, the anomaly is generally attributed to the Kear-Wilsdorf (K-W) mechanism. Since no parallel systematic TEM investigation has been performed to characterize the dislocation structures in Ni3Ge, it is not clear whether the yield stress anomaly below room temperature is governed mainly by the K-W mechanism or by other mechanism(s). Thus, detailed TEM characterization of dislocation dissociation has been carried out in polycrystalline Ni3Ge deformed at room temperature. In this report, we briefly describe the main results obtained. The complete analysis can be found elsewhere.The deformation structure mainly consists of apparently undissociated dislocations with Burgers’ vector parallel to a<110> and of SISF (super intrinsic stacking fault)-coupled partials. Fig. 1 shows an example of SISF dissociation. First, consider dissociation of a perfect dislocation into partials 1 and 2.

Plastic Deformation of Directionally-Solidified MoSi2/Mo5Si3 Eutectic Composites

2013 ◽  
Vol 1516 ◽  
pp. 195-200 ◽  
Author(s):  
Yuta Sasai ◽  
Atsushi Inoue ◽  
Kosuke Fujiwara ◽  
Kyosuke Kishida ◽  
Haruyuki Inui
Keyword(s):  
Plastic Deformation ◽  
Yield Stress ◽  
Deformation Behavior ◽  
Growth Direction ◽  
Average Thickness ◽  
Floating Zone ◽  
Directionally Solidified ◽  
Zone Method ◽  
Increasing Temperature ◽  
Loading Axis

ABSTRACTDeformation behavior of the directionally-solidified MoSi2/Mo5Si3 eutectic composites has been investigated as a function of the average thickness of MoSi2 phase over a temperature range from 900 to 1500°C. The average thickness of both MoSi2 and Mo5Si3 phases in the directionally-solidified ingots with script-lamellar morphologies grown by optical floating zone method decreases with increasing the growth rate. Plastic deformation was observed above 1000°C for all the DS ingots grown at different growth rates when the loading axis is parallel to [1¯10]MoSi2 close to the growth direction. Yield stress decreases monotonically with increasing temperature. Yield stress at 1400°C increases drastically with decreasing the average thickness of MoSi2 phase.

Deformation Behavior of Magnesium Single Crystal in c-Axis Compression and a-Axis Tension

2010 ◽  
Vol 654-656 ◽  
pp. 699-702 ◽  
Author(s):  
Shinji Ando ◽  
Masayuki Tsushida ◽  
Hiromoto Kitahara
Keyword(s):  
Yield Stress ◽  
Deformation Behavior ◽  
Compression Fracture ◽  
Anomalous Temperature ◽  
Twin Interface ◽  
Tension Tests ◽  
Axis Compression ◽  
Higher Temperature ◽  
General Deformation ◽  
Increasing Temperature

In general, deformation behavior of magnesium in compression is different from tensile. To investigate deformation behavior of magnesium single crystals by non-basal slips and twins, c-axis compression and a-axis tension tests were performed in the range of 77K-573K. The crystals were yielded by second order pyramidal slip, and the yield stress shows anomalous temperature dependence (increased with increasing temperature) between 203K and 293K. Yield stress of c-axis compression was bigger than that of a-axis tensile. In compression, fracture surface were (11 4) under 293K and were {30 4} above 373K, and fracture strain was smaller than the case of tension test. {10 1}-{10 2} double twin were activated at higher temperature and the crystal, therefore, fractured along the twin interface.

Deformation Behavior of Magnesium Single Crystals in C-Axis Compression

2007 ◽  
Vol 345-346 ◽  
pp. 129-132 ◽  
Author(s):  
Takaaki Kitahara ◽  
Shinji Ando ◽  
Masayuki Tsushida ◽  
Hiromoto Kitahara ◽  
Hideki Tonda
Keyword(s):  
Fracture Surface ◽  
Single Crystals ◽  
Yield Stress ◽  
Deformation Behavior ◽  
Anomalous Temperature Dependence ◽  
Anomalous Temperature ◽  
Pyramidal Slip ◽  
Axis Compression ◽  
General Deformation ◽  
Increasing Temperature

In general, deformation behavior of magnesium in compression is different from tensile. To investigate deformation behavior of magnesium single crystals, c-axis compression was performed. The crystals were yielded by second order pyramidal slip, and the yield stress shows anomalous temperature dependence (increased with increasing temperature) between 203K and 293K. Yield stress of c-axis compression is bigger than that of a-axis tensile. {10-13} twin and {11-24} twin occurred at 77293K and 77473K respectively. Fracture surface at 77293K was {11-24} and at 473K was {11-22}.

Temperature Dependence of Deformation Behavior in Magnesium and Magnesium Alloy Single Crystals

2007 ◽  
Vol 345-346 ◽  
pp. 101-104 ◽  
Author(s):  
Shinji Ando ◽  
Naoharu Harada ◽  
Masayuki Tsushida ◽  
Hiromoto Kitahara ◽  
Hideki Tonda
Keyword(s):  
Magnesium Alloy ◽  
Temperature Dependence ◽  
Single Crystals ◽  
Yield Stress ◽  
Deformation Behavior ◽  
Pure Magnesium ◽  
Pyramidal Slip ◽  
Increasing Temperature ◽  
Zn Alloy ◽  
Active Slip

It is important to research activation of the slip systems in magnesium crystals to understand deformation behavior of magnesium. In this study, pure magnesium, Mg-7.0at%Li and Mg-0.1at%Zn single crystals were stretched in the [11-20] direction in the range of 77K to 573K to investigate the deformation behavior by non-basal slip. The active slip system was investigated by the observation of slip bands, etch pit bands and dislocations by TEM. {11-22} <-1-123> second order pyramidal slip is activated in all magnesium and magnesium alloy single crystals, and its yield stress shows anomalous temperature dependence in the range from 77K to 293K, however, the yields stress decreased rapidly with increasing temperature above 293K. The yield stress due to the pyramidal slip in Mg-Li and Mg-Zn alloy were lower than that of pure magnesium about 20MPa whereas the stress of Mg-Zn at 77K was about two times higher than pure magnesium.

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