Simple Cubic to Face-Centered-Cubic, as Well as Trigonal Phase Transformations, Due to Inclusion of the Boron in the Lattices of Ni3Al Phase Found at the Grain Boundary Precipitate of Boron-Doped Ni3Al Alloy

2013 ◽  
pp. 821-828
Author(s):  
M. Shamsuzzoha
Keyword(s):  
Grain Boundary ◽  
Phase Transformations ◽  
Face Centered Cubic ◽  
Boundary Precipitate ◽  
Ni3al Alloy ◽  
Boron Doped ◽  
Simple Cubic ◽  
Ni3al Phase ◽  
Face Centered ◽  
Trigonal Phase

Hall-Petch Basis for Assessing Alloy Strengthening

1994 ◽  
Vol 362 ◽  
Author(s):  
Ronald W. Armstrong ◽  
R. Michael Douthwaite
Keyword(s):  
Grain Boundary ◽  
Alloy Composition ◽  
Friction Stress ◽  
Face Centered Cubic ◽  
Square Root ◽  
Petch Relation ◽  
Face Centered ◽  
Al Mg Alloys ◽  
Zn Alloys ◽  
Grain Boundary Strengthening

AbstractThe Hall-Petch relation σ = σo + kl−½, provides for the separate consideration of friction stress strengthening within the polycrystal grain volumes through σo and grain boundary strengthening through the product of the microstructural stress intensity k and the reciprocal square root of the grain diameter l Smaller grain diameters are normally obtained at higher alloy contents as illustrated for yield strength results reported for different face-centered-cubic Al-Mg alloys. Results on Al-Li alloy give an interesting example of substantial grain boundary strengthening that is associated with reduced ductility of the material. More complete results reported for the Cu-Al system, allow an evaluation of the strengthening component dependencies on alloy composition, in particular, connecting with a predicted square root of grain boundary obstacle stress in k. The much studied Cu-Zn alloys bring out subtle changes in σo and k

scholarly journals Pressure-Induced Dimerization of C60 at Room Temperature as Revealed by an In Situ Spectroscopy Study Using an Infrared Laser

Crystals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 182 ◽  
Author(s):  
Bing Li ◽  
Jinbo Zhang ◽  
Zhipeng Yan ◽  
Meina Feng ◽  
Zhenhai Yu ◽  
...  
Keyword(s):  
Room Temperature ◽  
Infrared Laser ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
Simple Cubic ◽  
Excitation Laser ◽  
Face Centered ◽  
830 Nm Laser ◽  
Structure Evaluation

Using in situ high-pressure Raman spectroscopy and X-ray diffraction, the polymerization and structure evaluation of C60 were studied up to 16 GPa at room temperature. The use of an 830 nm laser successfully eliminated the photo-polymerization of C60, which has interfered with the pressure effect in previous studies when a laser with a shorter wavelength was used as excitation. It was found that face-centered cubic (fcc) structured C60 transformed into simple cubic (sc) C60 due to the hint of free rotation for the C60 at 0.3 GPa. The pressure-induced dimerization of C60 was found to occur at about 3.2 GPa at room temperature. Our results suggest the benefit and importance of the choice of the infrared laser as the excitation laser.

Nearly Dislocation-Free APB Termination at Pure Grain Boundary Step Defects in L10 Alloys

1993 ◽  
Vol 319 ◽  
Author(s):  
Abha Singh ◽  
A.H. King
Keyword(s):  
High Temperature ◽  
Grain Boundary ◽  
Tetragonal Phase ◽  
Cubic Phase ◽  
Face Centered Cubic ◽  
Antiphase Boundaries ◽  
New Type ◽  
Face Centered ◽  
Fcc Phase ◽  
Step Defect

AbstractL10 alloys typically derive from a high-temperature, disordered fcc phase. For example, CuAu has a face centered tetragonal structure below 380°C and is derived from its high temperature, disordered face centered cubic phase. As the material transforms from the disordered fcc phase to the ordered tetragonal phase, the four distinct Σ3 fcc twin misorientations generate twelve distinct tetragonal twin misorientations, four being characterized as Σ3 and eight as Σ6. Of particular interest is the Σ6 structure because it is possible to terminate lattice antiphase boundaries without dislocations at this interface. A pure step defect at the interface can accommodate the APB termination due to anti-site coincidence (coincidence between copper and gold sites). We term these defects “antiphase steps”. The antiphase step is a new type of interfacial defect that has not been described by other workers. The possibility of forming antiphase steps in ordered L10 alloys is related to even-Σ interfaces. Since the Σ6 boundary is common in the ordered phase, the formation of dislocation-free APB terminations may be important in L10 alloys.

Zero-Point Effects in Heisenberg Antiferromagnets with Arbitrary Range of Interaction

1972 ◽  
Vol 50 (23) ◽  
pp. 2991-2996 ◽  
Author(s):  
M. F. Collins ◽  
V. K. Tondon
Keyword(s):  
Ground State ◽  
State Energy ◽  
Correction Term ◽  
Zero Point ◽  
Face Centered Cubic ◽  
Heisenberg Antiferromagnet ◽  
Body Centered Cubic ◽  
Cubic Lattices ◽  
Simple Cubic ◽  
Face Centered

The ground state energy, spin-wave energy, and sublattice magnetization have been calculated for a Heisenberg antiferromagnet at the absolute zero of temperature. The treatment extends the earlier work of Anderson, Kubo, and Oguchi to apply for any two-sublattice antiferromagnet with arbitrary range of interaction. It is shown that for each exchange interaction there is a different characteristic correction term to the energies. Explicit calculations are made of these terms for the simple cubic, body-centered cubic, and face-centered cubic lattices, with both first- and second-neighbor interactions. Applications are also made to NiO and MnO. An extra term in the magnetization series beyond that given by earlier workers is derived.

Enhancement Of Power Factor In A Thermoelectric Composite With A Periodic Microstructure

2000 ◽  
Vol 626 ◽  
Author(s):  
Leonid G. Fel ◽  
Yakov M. Strelniker ◽  
David J. Bergman
Keyword(s):  
Thermoelectric Power ◽  
Power Factor ◽  
The Other ◽  
Face Centered Cubic ◽  
Body Centered Cubic ◽  
High Quality ◽  
Thermoelectric Power Factor ◽  
Simple Cubic ◽  
Periodic Microstructures ◽  
Face Centered

ABSTRACTThe thermoelectric power factor has been calculated for a two-constituent composite medium, where one constituent is a “high quality thermoelectric” while the other constituent is a “benign metal”, with large electrical and thermal conductivities but poor thermoelectric properties. It was recently discovered that, in such a mixture, the power factor could be greatly enhanced by an appropriate choice of microstructure. Here we report on a study of three periodic microstructures with cubic point symmetry under rotations: simple cubic (SC), body centered cubic (BCC), and face centered cubic (FCC) arrays of identical spheres of the benign metal embedded in the high quality thermoelectric host. We show detailed results for these microstructures in the case where the benign metal constituent is Copper, while the high quality thermoelectric constituent is the thermoelectric alloy (Bi2Te3)0.2 (Sb2Te3)0.8.

scholarly journals The Effects of Mo and Nb on the Microstructures and Properties of CrFeCoNi(Nb,Mo) Alloys

Entropy ◽  
2018 ◽  
Vol 20 (9) ◽  
pp. 648 ◽  
Author(s):  
Chun-Huei Tsau ◽  
Meng-Chi Tsai
Keyword(s):  
Volume Fraction ◽  
Eutectic Structure ◽  
Close Packing ◽  
304 Stainless Steel ◽  
Hexagonal Close Packing ◽  
Face Centered Cubic ◽  
Simple Cubic ◽  
Corrosion Behaviors ◽  
Dendritic Microstructures ◽  
Face Centered

The effects of niobium and molybdenum additions on the microstructures, hardness and corrosion behaviors of CrFeCoNi(Nb,Mo) alloys were investigated. All of the CrFeCoNi(Nb,Mo) alloys displayed dendritic microstructures. The dendrites of CrFeCoNiNb and CrFeCoNiNb0.5Mo0.5 alloys were a hexagonal close packing (HCP) phase and the interdendrites were a eutectic structure of HCP and face-centered cubic (FCC) phases. Additionally, the dendrites of CrFeCoNiMo alloys were a simple cubic (SC) phase and the interdendrites were a eutectic structure of SC and FCC phases. The volume fraction of dendrites and interdendrites in these alloys were calculated. The influences of the volume fraction of dendrite in the alloys on the overall hardness were also discussed. The CrFeCoNiNb alloy had the larger volume fraction of dendrite and thus had the highest hardness among these alloys. The CrFeCoNi(Nb,Mo) alloys also showed better corrosion resistances in 1 M H2SO4 and 1 M NaCl solutions by comparing with commercial 304 stainless steel. The CrFeCoNiNb0.5Mo0.5 alloy possessed the best corrosion resistances in these solutions among the CrFeCoNi(Nb,Mo) alloys.

On the new structural phases in Al65Cu20Cr15 quasicrystalline alloy

1995 ◽  
Vol 10 (8) ◽  
pp. 1905-1912 ◽  
Author(s):  
Varsha Khare ◽  
N.P. Lalla ◽  
R.S. Tiwari ◽  
O.N. Srivastava
Keyword(s):  
Metastable Phase ◽  
Structural Characteristics ◽  
Icosahedral Phase ◽  
Cubic Phase ◽  
Face Centered Cubic ◽  
Body Centered Cubic ◽  
Structural Variants ◽  
Simple Cubic ◽  
Face Centered ◽  
Specific Orientation

The quasicrystalline (qc) alloy Al65Cu20Cr15, unlike its Ru- and Fe-bearing counterparts like Al65Cu20Ru15 and Al65Cu20Fe15, is a metastable phase. This qc alloy has been shown to possess several structural variants and curious structural characteristics. We have investigated the qc alloy Al65Cu20Cr15 with special reference to the possible occurrence of new structural variants. TEM exploration of the as-quenched qc alloy has indeed revealed the existence of several new phases. These are (i) body-centered cubic (bcc) (a = 12.60 Å, disordered) and simple cubic (s.c.) (a = 12.60 Å, ordered), which are the 1/1 approximants of the primitive icosahedral phase (i phase); (ii) a twice order-induced modulated cubic phase (bcc, a = 25.20 Å) which has been shown to correspond to 1/1 approximant of the ordered i phase [i.e., face-centered icosahedral (FCI)]; and (iii) real crystalline bcc (a = 8.90 Å) and face-centered cubic (fcc) (a = 17.98 Å) phases possessing a specific orientation relationship with the icosahedral matrix phase. Tentative structural models showing the interrelationships between the bcc/fcc phases have been outlined.

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