Alloy Modeling and Experimental Correlation for Ductility Enhancement in NiAl

1988 ◽  
Vol 133 ◽  
Author(s):  
R. Darolia ◽  
D. F. Lahrman ◽  
R. D. Field ◽  
A. J. Freeman
Keyword(s):  
Room Temperature ◽  
Boundary Energy ◽  
Ternary Alloys ◽  
Total Electron ◽  
Solid Solution Strengthening ◽  
Band Structure Calculations ◽  
Solution Strengthening ◽  
Anti Phase Boundary ◽  
Structure Calculations ◽  
Electron Band Structure

ABSTRACTSingle crystals of stoichiometric NiAl and NiAl+V alloys were tested in compression and tension from room temperature to 871°C to determine deformation behavior. The dislocations were predominately <100> in the plastically deformed specimens. Attempts to ductilize NiAl by the addition of vanadium are described. The lowering of the anti-phase boundary energy by vanadium addition to NiAl, believed to promote the formation of <111> dislocations, was predicted by the all electron self consistent total electron band structure calculations. The vanadium additions caused considerable solid solution strengthening in NiAl, rendering the ternary alloys more brittle than stoichiometric NiAl.

The Influence of Secondary Phase on Impact Toughness of Alloyed Iron Aluminides

2020 ◽  
Vol 405 ◽  
pp. 145-150
Author(s):  
Martin Švec ◽  
Adam Hotař ◽  
Věra Vodičková ◽  
Vojtěch Keller
Keyword(s):  
Impact Toughness ◽  
Room Temperature ◽  
Volume Fraction ◽  
Fracture Behaviour ◽  
Secondary Phase ◽  
Iron Aluminides ◽  
The Other ◽  
Secondary Phases ◽  
Solid Solution Strengthening ◽  
Solution Strengthening

The microstructure and fracture surfaces were investigated for five Fe3Al – based iron aluminides doped by different alloying elements (Nb, Zr + C, Cr) or without addition. Generally, iron aluminides are considered as brittle material at room temperature, therefore the type and distribution of secondary phases affect the fracture behaviour. The influence of present secondary phase particles on impact toughness at room temperature was evaluated in comparison to binary alloy. The type and the volume fraction of particles affect the value of impact toughness significantly – these values decrease with increasing volume fraction of precipitates. On the other hand, the solid solution strengthening improves impact toughness.

Development of Tough and Strong Cubic Titanium Trialuminides

2000 ◽  
Vol 646 ◽  
Author(s):  
Robert A. Varin ◽  
Les Zbroniec ◽  
Zhi Gang Wang
Keyword(s):  
Fracture Toughness ◽  
Fracture Behavior ◽  
Room Temperature ◽  
Fold Increase ◽  
Strength Increase ◽  
Solid Solution Strengthening ◽  
Boron Doped ◽  
Temperature Fracture ◽  
Solution Strengthening ◽  
B Doping

ABSTRACTIn this work, the recent breakthroughs in the understanding of the fracture behavior and fracture toughness of L12-ordered titanium trialuminides are described and discussed. First, it is shown that, as opposed to many other intermetallics and specifically those with an L12 crystal structure, the fracture toughness of L12 titanium trialuminides is insensitive to testing in various environments such as air, water, argon, oxygen and vacuum (∼1.3×10–5 Pa). Second, it is reported here that by increasing the concentration of Ti combined with boron (B) doping, the room temperature fracture toughness of a Mn-stabilized titanium trialuminide can be improved by 100% from ∼4 MPam1/2 to ∼8 MPam1/2 and by 150–250% at 1000°C to ∼(10–12) MPam1/2 with a simultaneous suppression of intergranular fracture (IGF) to ∼(40–50%). Almost three fold increase in yield strength to ∼550 MPa is attained at room temperature for high Ti, boron-doped trialuminides. Both Vickers microhardness and strength increase linearly with increasing concentration of (Ti+B) indicating a classical solid solution strengthening response.

New Conjugated Polymers Derived from Carbazole as Thermoelectric Materials

2005 ◽  
Vol 871 ◽  
Author(s):  
Isabelle Lévesque ◽  
Xing Gao ◽  
Christopher I. Ratcliffe ◽  
Dennis D. Klug ◽  
John S. Tse ◽  
...  
Keyword(s):  
Band Structure ◽  
Seebeck Coefficient ◽  
Conjugated Polymers ◽  
Power Factor ◽  
Thermoelectric Materials ◽  
Doping Level ◽  
Room Temperature ◽  
Polymer Structure ◽  
Band Structure Calculations ◽  
Structure Calculations

AbstractNovel poly(3,6-hexyl-2,7-N-octylcarbazole) derivatives and poly(diindolocarbazole)s were synthesized. Optical, electrochemical, electrical and thermoelectric properties were investigated. Band structure calculations were used to predict which polymers were promising as thermoelectric materials. The best combination of Seebeck coefficient and conductivity (power factor) was 9,4 x10-8 Wm-1K-2 with a copolymer of carbazole and thiophene. This corresponds to a ZT at room temperature of 0.0003. Optimization of the polymer structure and doping level should lead to an increased ZT.

scholarly journals The morphology of an intercalated Au layer with its effect on the Dirac point of graphene

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Amirhossein Bayani ◽  
Karin Larsson
Keyword(s):  
Density Functional ◽  
Room Temperature ◽  
Dirac Point ◽  
Wide Bandgap ◽  
Point Of View ◽  
Experimental Point ◽  
Functional Theory ◽  
Band Structure Calculations ◽  
Graphene Interface ◽  
Structure Calculations

AbstractThis is a theoretical investigation where Density Functional Theory (DFT) has been used in studying the phenomenon of Au intercalation within the 4H-SiC/graphene interface. The electronic structure of some carefully chosen morphologies of the Au layer has then been of special interest to study. One of these specific Au morphologies is of a more hypothetical nature, whilst the others are, from an experimental point of view, realistic ones. The latter ones were also found to be energetically stable. Band structure calculations showed that intercalated Au layers with morphologies different from a planar Au layer will induce a band gap at the Dirac point of graphene (with up to 174 meV for the morphologies studied in the present work). It should here be mentioned that this bandgap size is four times larger than the energy of thermal motion at room temperature (26 meV). These findings reveal that a wide bandgap at the Dirac point of graphene comes from an inhomogeneous staggered potential on the Au layer, which non-uniformly breaks the sublattice symmetry. The presence of spin-orbit (SO) interactions have also been included in the present study, with the purpose to find out if SO will create a bandgap and/or band splitting of graphene.

Mechanical Behavior of Ternary and Quaternary Rual Alloys

2002 ◽  
Vol 753 ◽  
Author(s):  
T. K. Nandy ◽  
Q. Feng ◽  
D. Banerjee ◽  
M. F. X. Gigliotti ◽  
T. M. Pollock
Keyword(s):  
Mechanical Behavior ◽  
Room Temperature ◽  
Rate Sensitivity ◽  
Intermetallic Alloys ◽  
Compression Tests ◽  
Solid Solution Strengthening ◽  
Deformation Substructure ◽  
Substructure Analysis ◽  
Flow Mechanisms ◽  
Solution Strengthening

ABSTRACTThe mechanical behavior of RuAl-base intermetallic alloys with alloying additions of boron, niobium and platinum has been investigated. Compression tests have been performed at room temperature and 973 K. While the addition of alloying elements results in solid solution strengthening, the strain-rate sensitivity and the activation volumes do not show a significant variation, thereby suggesting that the macroscopic flow mechanisms are not strongly affected. Deformation substructure analysis of the niobium-containing alloy shows the presence of <100> and <110> dislocations, while the platinum-containing alloy additionally contains a significant density of <111> dislocations.

Strength, Ductility, and Fracture Mode of Ternary FeAl Alloys

1994 ◽  
Vol 364 ◽  
Author(s):  
J. H. Schneibel ◽  
E. P. George ◽  
E. D. Specht ◽  
J. A. Horton
Keyword(s):  
Binary Alloy ◽  
Fracture Mode ◽  
Single Phase ◽  
Ternary Alloys ◽  
Transgranular Fracture ◽  
Atomic Size ◽  
Solid Solution Strengthening ◽  
Ternary Element ◽  
Solution Strengthening ◽  
Ternary Alloying

AbstractIron aluminides with the composition Fe-45Al-5X-0.2B-0.1Zr (at. %), where X stands for the first row transition metals Ti, V, Cr, Mn, Fe, Co, Ni, Cu, were examined at room temperature with respect to their strength, ductility, environmental sensitivity, and fracture mode. The extruded materials were annealed at 1273 K to produce similar grain sizes and subsequently at 673 K to reduce the amount of quenched in vacancies. All alloys were essentially single phase. Their solid solution strengthening was found to correlate with the atomic size misfit derived from the lattice parameters. The “binary” alloy Fe-45Al-0.2B-0.1Zr exhibited predominantly transgranular fracture. Ternary alloying additons with atomic numbers less than that of Fe tended to enhance intergranular fracture, whereas those with atomic numbers higher than that of Fe favored substantial amounts of transgranular fracture. Tensile testing in a partial pressure of dry oxygen increased the ductilities of the ternary alloys only slightly, whereas the ductility of the binary alloy increased from about 8 to about 19%. The ductilities in air correlated inversely with the yield strength. However, those alloys exhibiting substantial amounts of transgranular fracture always showed higher ductilities than those fracturing intergranularly. We interpret our fracture results in terms of yield strengths and ternary element site occupations.

Synthesis and Characterization of Double Perovskites Sr2FeMO6 (M = Mo, W)

2003 ◽  
Vol 17 (18n20) ◽  
pp. 3500-3502
Author(s):  
T. S. Chan ◽  
R. S. Liu ◽  
G. Y. Guo ◽  
C. Y. Huang
Keyword(s):  
Room Temperature ◽  
Magnetic Measurements ◽  
Transition Metal Ions ◽  
Double Perovskites ◽  
Oxygen Ions ◽  
Physical Measurements ◽  
Band Structure Calculations ◽  
Magnetoresistance Ratio ◽  
Structure Calculations

We have investigated the magnetic and magnetotransport properties of monophasic double perovskites Sr 2 FeMO 6( M = Mo , W ). Magnetic measurements indicate that SFMO is a ferromagnet and SFWO is an antiferromagnet with TN = 35 K at H = 5 T . Large magnetoresistance ratio (MR) of ~ 22% (H = 3 T ) at room temperature (RT) was observed in the SFWO compound. However, the SFMO compound did not show any significant MR even at high fields and RT (MR~1%; H = 3 T and 300 K). The changes observed by physical measurements are supported by band structure calculations to explain the interaction between the 3d (Fe) , 4d (Mo) and 5d (W) orbitals of transition metal ions and oxygen ions.

The Effect of Test Temperature on Deformation Microstructure and Fracture Mechanisms in CrMn High-Nitrogen Steels Alloyed (0-3 wt.%) with Vanadium

2018 ◽  
Vol 941 ◽  
pp. 27-32 ◽  
Author(s):  
Elena Astafurova ◽  
Valentina Moskvina ◽  
Galina G. Maier ◽  
Eugene Melnikov ◽  
Nina Galchenko ◽  
...  
Keyword(s):  
Solid Solution ◽  
Test Temperature ◽  
Room Temperature ◽  
High Nitrogen ◽  
Interstitial Solid Solution ◽  
Vanadium Concentration ◽  
Solid Solution Strengthening ◽  
Solution Strengthening ◽  
Nitrogen Steels ◽  
Particle Strengthening

A temperature dependence of the tensile mechanical properties, microstructure and fracture mechanism of high-nitrogen Fe-(19-23)Cr-(17-21)Mn-(0-3)V-(0.1-0.3)C-(0.5-0.9)N vanadium-free and vanadium-containing steels was investigated. For all steels, the 0.2% offset yield strength and strain-hardening drastically increase with a decrease in test temperature. This is associated with high interstitial solid solution strengthening of the steels and more pronounced twinning and stacking-fault formation during straining below room temperature. For the vanadium-free steel, a ductile-to-brittle transition was evaluated: at 77K specimens destroy by cleavage mechanism while at room temperature steels show ductile fracture. Vanadium-alloying provides a particle strengthening of the steels and, at the same time, reduce solid-solution strengthening. Increase of vanadium concentration fully or partially suppress brittle fracture of the steels at 77K. Particle strengthening changes interstitial solid-solution effect, dislocation arrangement and slip/twinning relation in vanadium-containing high-nitrogen steels compared to vanadium-free one.

Two-dimensional stable Mn based half metal and antiferromagnets promising for spintronics

Nanoscale ◽  
2020 ◽  
Vol 12 (23) ◽  
pp. 12490-12496 ◽  
Author(s):  
Bingwen Zhang ◽  
Guang Song ◽  
Jie Sun ◽  
Jiancai Leng ◽  
Cheng Zhang ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Band Structure ◽  
Monte Carlo Simulations ◽  
Room Temperature ◽  
Mechanical Stability ◽  
Two Dimensional ◽  
Half Metallic ◽  
Half Metal ◽  
Band Structure Calculations ◽  
Structure Calculations

By phonon band structure calculations and Monte Carlo simulations, we propose that 2D MnSi and MnC0.5Si0.5 monolayers could exhibit mechanical stability and room temperature half-metallic properties.

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