COMPRESSION CREEP BEHAVIOR OF B2 AL-NI-RU TERNARY ALLOYS

2006 ◽  
Vol 980 ◽  
Author(s):  
Fang Cao ◽  
Tresa M. Pollock
Keyword(s):  
Creep Behavior ◽  
Phase Field ◽  
Creep Resistance ◽  
Ternary Alloys ◽  
Continuous Increase ◽  
Screw Dislocations ◽  
Compression Creep ◽  
Transient Experiments ◽  
B2 Phase ◽  
Edge Dislocations

AbstractThe compression creep behavior of five Al- Ni-Ru ternary alloys with compositions across the NiAl-RuAl B2 phase field has been investigated within the temperature range of 950 °C to 1050 °C. A continuous increase of the melting temperature and creep resistance with increasing Ru/Ni ratio in these alloys was observed. Post-creep dislocation analyses identified the presence of <100> and <110> edge dislocations in the Al-deficient alloys. Conversely, jogged <100> screw dislocations predominated in the Ru-rich ternary alloys. Dislocation substructures and transient experiments suggest a transition of the creep mechanism from viscous glide controlled to jogged screw motion in these alloys.

The Compression Creep Behavior of Ni3Al-X Single Crystals

1990 ◽  
Vol 213 ◽  
Author(s):  
Seiji Miura ◽  
Tohru Hayashi ◽  
Mitsuhiro Takekawa ◽  
Yoshinao Mishima ◽  
Tomoo Suzuki
Keyword(s):  
Activation Energy ◽  
Single Crystals ◽  
Power Law ◽  
Creep Behavior ◽  
Creep Resistance ◽  
Constant Strain Rate ◽  
State Equation ◽  
Ternary Alloys ◽  
Plastic Behavior ◽  
Compression Tests

ABSTRACTCompressive creep behavior is investigated in ternary Ni3Al single crystals containing Ti, Si, Hf and Cr with stress axes parallel to the crystallographic orientation near [001]. Then a comparison is made with the results of high temperature compression tests under a constant strain rate for the same orientation where plastic behavior is characterized by a distinct yield drop followed by steadystate deformation. It is found that the deformation mechanism for the two cases is identical, namely octahedral viscous flow being expressed by the state equation of the power-law type with a stress exponent of about 3 to 4. The effect of offstoichiometry on the creep resistance is then examined in Ni3(Al,5 at%Ti) alloys with different Ni concentrations. The results support the observation in the polycrystalline compound where the creep resistance increases with Ni concentration on both sides of stoichiometry exhibiting a discontinuity at stoichiometry. Finally, the apparent activation energy in the power-law type state equation for the steady state creep deformation is estimated for all the ternary alloys examined. They are in general in good agreement with that for diffusion of ternary elements in Ni3Al. However, the relative magnitude of the value can not simply be compared since the activation energy depends on deviations from stoichiometry.

Effect of heating rate inα+γdual-phase field on lamellar microstructure and creep resistance of a TiAl alloy

2005 ◽  
Vol 96 (6) ◽  
pp. 584-588
Author(s):  
Kouichi Maruyama ◽  
Jun Matsuda ◽  
Hanliang Zhu
Keyword(s):  
Heating Rate ◽  
Phase Field ◽  
Creep Resistance ◽  
Tial Alloy ◽  
Lamellar Microstructure

Effect of Equal-Channel Angular Pressing (ECAP) on Creep in Aluminium Alloys

2007 ◽  
Vol 539-543 ◽  
pp. 2904-2909 ◽  
Author(s):  
Vàclav Sklenička ◽  
Jiří Dvořák ◽  
Marie Kvapilová ◽  
Milan Svoboda ◽  
Petr Král ◽  
...  
Keyword(s):  
Equal Channel Angular Pressing ◽  
Aluminium Alloys ◽  
Creep Resistance ◽  
Room Temperature ◽  
Creep Behaviour ◽  
Coarse Grained ◽  
Pure Aluminium ◽  
Creep Tests ◽  
Angular Pressing ◽  
Compression Creep

This paper examines the effect of equal-channel angular pressing (ECAP) on creep behaviour of pure aluminium, binary Al-0.2wt.%Sc alloy and ternary Al-3wt.%Mg-0.2wt.%Sc alloy. The ECAP was conducted at room temperature with a die that had a 90° angle between the channels and 8 repetitive ECAP passes followed route BC. Constant stress compression creep tests were performed at 473 K and stresses ranging between 16 to 80 MPa on ECAP materials and, for comparison purposes, on the initial coarse-grained materials. The results showed that the creep resistance of the ECAP processed Al-Sc and Al-Mg-Sc alloys was markedly deteriorated with respect to unpressed coarse-grained materials.

Microstructures and Creep of AM50-Sb-Gd Alloys

2005 ◽  
Vol 488-489 ◽  
pp. 749-752 ◽  
Author(s):  
Su Gui Tian ◽  
Keun Yong Sohn ◽  
Hyun Gap Cho ◽  
Kyung Hyun Kim
Keyword(s):  
Activation Energy ◽  
Creep Rate ◽  
Stress Exponent ◽  
Creep Behavior ◽  
Creep Deformation ◽  
Deformation Mechanism ◽  
Creep Resistance ◽  
Fine Particles ◽  
Dislocation Climb ◽  
The Matrix

Creep behavior of AM50-0.4% Sb-0.9%Gd alloy has been studied at temperatures ranging from 150 to 200°C and at stresses ranging from 40 to 90 MPa. Results show that the creep rate of AM50-0.4%Sb-0.9%Gd alloy was mainly controlled by dislocation climb at low stresses under 50 MPa. The activation energy for the creep was 131.2 ± 10 kJ/mol and the stress exponent was in the range from 4 to 9 depending on the applied stress. More than one deformation-mechanism were involved during the creep of this alloy. Microstructures of the alloy consist of a–Mg matrix and fine particles, distinguished as Mg17Al12, Sb2Mg3, and Mg2Gd or Al7GdMn5 that were homogeneously distributed in the matrix of the alloy, which effectively reduced the movement of dislocations, enhancing the creep resistance. Many dislocations were identified to be present on non-basal planes after creep deformation.

High Temperature Creep Behavior and Effects of Stacking Fault Energy in Mg-Y and Mg-Y-Zn Dilute Solid Solution Alloys

2014 ◽  
Vol 783-786 ◽  
pp. 491-496
Author(s):  
Mayumi Suzuki ◽  
Yasuyuki Murata ◽  
Kyosuke Yoshimi
Keyword(s):  
Activation Energy ◽  
Solid Solution ◽  
Creep Behavior ◽  
Ternary Alloys ◽  
Dislocation Creep ◽  
Prismatic Slip ◽  
Dislocation Slip ◽  
Self Diffusion ◽  
Controlling Mechanism ◽  
Hot Rolled

Compressive creep behavior of hot-rolled (40%) Mg-Y binary and Mg-Y-Zn ternary dilute solid solution alloys are investigated in this study. Creep strength is substantially improved by the addition of zinc. Activation Energy for creep in Mg-Y and Mg-Y-Zn alloys are around 200 kJ/mol at the temperature range from 480 to 570 K. These values are higher than the activation energy for self-diffusion coefficient in magnesium (135 kJ/mol). Many stacking faults, which are planar type defects are observed on the basal planes of the magnesium matrix in Mg-Y-Zn ternary alloys. TEM observation has been revealed that the non-basal a-dislocation slip is significantly activated by these alloys. The rate controlling mechanism of Mg-Y and Mg-Y-Zn dilute alloys are considered to the cross-slip or prismatic-slip controlled dislocation creep with high activation energy for creep, more than 1.5 times higher than the activation energy for creep controlled dislocation climb.

The Effect of Second Phase Properties on the Compression Creep Behavior of MoSi2 Composites

1992 ◽  
Vol 273 ◽  
Author(s):  
A. K. Ghosh ◽  
A. Basu ◽  
H. Kung
Keyword(s):  
Grain Size ◽  
Creep Behavior ◽  
Creep Strength ◽  
Relative Strength ◽  
Second Phase ◽  
Compression Creep ◽  
Phase Properties

ABSTRACTIn an effort to enhance the toughness and creep strength of MoSi2, the role of various metallic and ceramic reinforcements is being examined. In this work, the effects of an oxide, a carbide and a nitride reinforcement on the compression creep behavior of MoSi2 are explored. Variations in the deformability of reinforcements and their relative strength and flaw population appear to influence the creep strength of the composites. Refinements in grain size also improve crack tolerance of the composite during deformation at 1200°C.

Characterization of Dislocations and Micropipes in 4H n+ SiC Substrates

2008 ◽  
Vol 600-603 ◽  
pp. 333-336 ◽  
Author(s):  
Ping Wu ◽  
Murugesu Yoganathan ◽  
Ilya Zwieback ◽  
Yi Chen ◽  
Michael Dudley
Keyword(s):  
Etch Pits ◽  
Screw Dislocations ◽  
X Ray ◽  
Nitrogen Doped ◽  
Different Types ◽  
History Of ◽  
Density Analysis ◽  
Threading Defects ◽  
Edge Dislocations

Etching of 4H-SiC wafers in molten KOH as a method for micropipe and dislocation density analysis was investigated. The obtained results were correlated with those of the synchrotron white beam x-ray topography. Heavily nitrogen-doped SiC shows a significantly different etching behavior in comparison with the low-doped material. This complicates identification of different types of threading defects. In particular, it is difficult to separate Threading Screw Dislocations (TSD) from Threading Edge Dislocations (TED). Depending on the level of doping and thermal history of the crystal, some of the etch pits emerging due to the 1c screw dislocations can be as large as those due to the micropipes.

Differences in Emission Spectra of Dislocations in 4H-SiC Epitaxial Layers

2008 ◽  
Vol 600-603 ◽  
pp. 345-348 ◽  
Author(s):  
Kendrick X. Liu ◽  
X. Zhang ◽  
Robert E. Stahlbush ◽  
Marek Skowronski ◽  
Joshua D. Caldwell
Keyword(s):  
Spectral Characteristics ◽  
Emission Spectra ◽  
Spectral Peak ◽  
Epitaxial Layers ◽  
Threading Dislocations ◽  
Screw Dislocations ◽  
Material Defects ◽  
Partial Dislocations ◽  
Edge Dislocations ◽  
Non Destructive

Material defects such as Si-core and C-core partial dislocations (PDs) and threading screw dislocations (TSDs) and threading edge dislocations (TEDs) are being investigated for their contributions to device performances in 4H-SiC. Non-destructive electroluminescence and photoluminescence techniques can be powerful tools for examining these dislocations. In this report, these techniques were used to reveal the different spectral characteristics for the mentioned dislocations. At higher injection levels, both the Si-core and C-core PDs possessed a spectral peak at 700 nm. However, at lower injection levels, the spectral peak for the Si-core PD remained at 700 nm while the peak for the C-core moved to longer wavelengths. For the threading dislocations, TSDs possessed a peak between 800 and 850 nm while the TEDs possessed a peak at 600 nm independent of the injection levels.

scholarly journals Long-Term Creep Behavior Prediction of Sol-Gel Derived SiO2- and TiO2-Wood Composites Using the Stepped Isostress Method

Polymers ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1215 ◽  
Author(s):  
Ke-Chang Hung ◽  
Tung-Lin Wu ◽  
Jyh-Horng Wu
Keyword(s):  
Creep Behavior ◽  
Creep Resistance ◽  
Flexural Modulus ◽  
Sol Gel ◽  
Untreated Wood ◽  
Behavior Prediction ◽  
Inorganic Composites ◽  
Sol Gel Process ◽  
Term Creep

In this study, methyltrimethoxysilane (MTMOS), methyltriethoxysilane (MTEOS), tetraethoxysilane (TEOS), and titanium(IV) isopropoxide (TTIP) were used as precursor sols to prepare wood-inorganic composites (WICs) by a sol-gel process, and subsequently, the long-term creep behavior of these composites was estimated by application of the stepped isostress method (SSM). The results revealed that the flexural modulus of wood and WICs were in the range of 9.8–10.5 GPa, and there were no significant differences among them. However, the flexural strength of the WICs (93–103 MPa) was stronger than that of wood (86 MPa). Additionally, based on the SSM processes, smooth master curves were obtained from different SSM testing parameters, and they fit well with the experimental data. These results demonstrated that the SSM was a useful approach to evaluate the long-term creep behavior of wood and WICs. According to the Eyring equation, the activation volume of the WICs prepared from MTMOS (0.825 nm3) and TEOS (0.657 nm3) was less than that of the untreated wood (0.832 nm3). Furthermore, the WICs exhibited better performance on the creep resistance than that of wood, except for the WICMTEOS. The reduction of time-dependent modulus for the WIC prepared from MTMOS was 26% at 50 years, which is the least among all WICs tested. These findings clearly indicate that treatment with suitable metal alkoxides could improve the creep resistance of wood.

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