scholarly journals Control of Microstructure for Co-Cr-Mo Fibers Fabricated by Unidirectional Solidification

Crystals ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 11
Author(s):  
Shoki Abe ◽  
Yuui Yokota ◽  
Takayuki Nihei ◽  
Masao Yoshino ◽  
Akihiro Yamaji ◽  
...  
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Growth Direction ◽  
Unidirectional Solidification ◽  
Face Centered Cubic ◽  
Close Packed Structure ◽  
Ε Phase ◽  
Hexagonal Close Packed Structure ◽  
Packed Structure ◽  
Face Centered

Co-Cr-Mo alloy fibers of 2 mm in diameter were fabricated from the melt at 1, 2, and 5 mm/min growth rates by unidirectional solidification using an alloy-micro-pulling-down (A-µ-PD) method to control the microstructure. All elements, Co, Cr, and Mo, were distributed in stripes elongated along the growth direction due to constitutional undercooling. Both Co-Cr-Mo fibers fabricated at 2 and 5 mm/min growth rates were composed of the γ phase with a face-centered cubic structure (fcc-γ phase) and ε-phase with a hexagonal close-packed structure (hcp-ε phase), and the ratio of the fcc-γ phase in the fiber fabricated at 5 mm/min growth rate was higher than that in the fiber fabricated at 2 mm/min. The results suggest that a faster growth rate increases the ratio of the fcc-γ phase in the Co-Cr-Mo fiber fabricated by unidirectional solidification.

INTERFACES BETWEEN CARBON NANOTUBES AND NICKEL NANOPARTICLES IN CARBON NANOTUBES

2013 ◽  
Vol 06 (06) ◽  
pp. 1350056 ◽  
Author(s):  
BAI LIU ◽  
LIRUI LIU
Keyword(s):  
Carbon Nanotubes ◽  
Rechargeable Batteries ◽  
Dislocation Model ◽  
Face Centered Cubic ◽  
Hexagonal Close Packed ◽  
Close Packed Structure ◽  
Hexagonal Close Packed Structure ◽  
Packed Structure ◽  
Cnts Surface ◽  
Face Centered

Carbon nanotubes (CNTs) filled with metals can be used in capacitors, sensors, rechargeable batteries, and so on. Their interface significantly affects the properties of the composites. Here, we show that three kinds of interfaces between crystalline Ni and CNTs exist, namely, ordered, distorted, and disordered. They presented lattice states of Ni atoms near the interface, whereas the (111) Ni plane was parallel to the CNTs' surface and appeared apart in a smaller or bigger angle. The coherent face-centered cubic (f.c.c)/hexagonal close-packed structure (h.c.p) boundary was formed between the crystalline Ni and CNTs at the ordered interface, in which the match was (111) Ni //(0001) Carbon . We suggested a dislocation model for the coherent interface. The model explained why the angle between (200) Ni and the CNTs' inner surface was 52.9° rather than the theoretical value of 54.75°. The [Formula: see text] dislocation was formed to fit the coherent relationship. Thus, Ni lattice shrinkage occurred. Further study indicated that the formation mechanism of crystalline Ni in CNTs was through heterogeneous nucleation on the inner wall surface and growth of the crystal nucleus.

Deformation-induced γ → DI-α2 phase transformation occurring in the twin-intersection region of TiAl alloys

2007 ◽  
Vol 22 (9) ◽  
pp. 2416-2422 ◽  
Author(s):  
C.L. Chen ◽  
W. Lu ◽  
L.L. He ◽  
H.Q. Ye
Keyword(s):  
Phase Transformation ◽  
Room Temperature ◽  
Compositional Analysis ◽  
Hexagonal Close Packed ◽  
Partial Dislocations ◽  
Close Packed Structure ◽  
The Matrix ◽  
Hexagonal Close Packed Structure ◽  
Packed Structure ◽  
Face Centered

Deformation-induced γ → DI-α2 phase transformation was verified to occur in the twin-intersection region of a Ti–45Al–8Nb (at.%) alloy compressed at room temperature. High-resolution image observations of the deformation-induced DI-α2 phase suggested that the orientation relationship between the DI-α2 and γ phases remained the typical one: (0001)DI−α2//{111}γ, [11¯20]DI−α2//〈101]γ. The conversion of stacking sequence from ordered face-centered tetragonal to ordered nonequilibrium hexagonal close-packed structure was accomplished by the movement of a/6〈11¯2] Shockley partial dislocations on every other {111}γ plane. Compositional analysis based on energy dispersive spectra revealed that the DI-α2 phase had the same composition as the matrix γ phase. No compositional diffusion occurred because the plastic deformation was carried out at room temperature. The strong stress concentration in the intersection region was the major force to induce the γ → DI-α2 phase transformation in the process of room-temperature compression.

Size and Composition Effects in the Structure and Properties of Polymer-Protected Bimetallic Particles

2001 ◽  
Vol 704 ◽  
Author(s):  
Marie-José Casanove ◽  
Pierre Lecante ◽  
Marie-Claire Fromen ◽  
Marc Respaud ◽  
David Zitoun ◽  
...  
Keyword(s):  
Structural Evolution ◽  
Magnetic Behavior ◽  
Organic Matrix ◽  
Face Centered Cubic ◽  
Bimetallic Particles ◽  
Close Packed Structure ◽  
Hexagonal Close Packed Structure ◽  
The Face ◽  
Face Centered ◽  
Size Dispersion

AbstractWe investigate the structural evolution of PtRu and CoRh ultra fine bimetallic particles as a function of their composition in the whole range of stoichiometry. Isolated particles embedded in an organic matrix are synthesized using chemical techniques in mild conditions. Their size, dispersion and structure are analyzed by HRTEM, WAXS and EXAFS techniques. The magnetic behavior of cobalt-based alloys is investigated by SQUID magnetometry. In the PtRu alloys, we demonstrate the role of composition in the structural transition from the face-centered cubic to the hexagonal close packed structure in nanoparticles and detail the mechanism of the transition. We point out the effect of size reduction and core-shell atomic distribution in the structure and the enhanced magnetization in CoRh bimetallic particles.

Formation of Defects by Stretching Gold Nanosheet - A Simulation Study

2013 ◽  
Vol 24 ◽  
pp. 146-154 ◽  
Author(s):  
Sumali Bansal ◽  
Keya Dharamvir
Keyword(s):  
Tensile Deformation ◽  
Morphological Evolution ◽  
Face Centered Cubic ◽  
Many Body ◽  
Key Factors ◽  
Close Packed Structure ◽  
Structural Deformations ◽  
Packed Structure ◽  
Face Centered ◽  
Gupta Potential

Under tensile deformation, gold nanosheets elongate to form defects via a series of small vacancies leading to structural deformations. Behavior of finite gold nanosheets containing 57 and 73 atoms under load are investigated modeled by many-body Gupta potential. Nanosheets with close packed structure (111) plane of a face-centered-cubic structure are stretched along one of the two symmetry directions of the plane. The accessibility of these structures and their stability under load are found to be the key factors governing the morphological evolution of the gold nanosheets. It is found that major deformation is the formation of vacancies which could be called defects in the sheets and is surprisingly different from the ultimate stretching of a nanocylinder which is via neck formation. Thus this study presents completely new theoretical results for gold nanosheets.

Two-dimensional silicon monolayers generated on c-BN(111) substrate

2015 ◽  
Vol 17 (24) ◽  
pp. 15694-15700 ◽  
Author(s):  
Haiping Wu ◽  
Yan Qian ◽  
Shaohua Lu ◽  
Erjun Kan ◽  
Ruifeng Lu ◽  
...  
Keyword(s):  
Type Structure ◽  
Two Dimensional ◽  
Compound Structure ◽  
Hexagonal Close Packed ◽  
Close Packed Structure ◽  
Hexagonal Close Packed Structure ◽  
Packed Structure ◽  
Chain Type

Three Si monolayer structures, a Si chain-type structure, a two-dimensional hexagonal close packed compound structure, and a two-dimensional hexagonal close packed structure, are generated on a c-BN(111) substrate.

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