Coherency Strain of an Overgrown Island

1989 ◽  
Vol 148 ◽  
Author(s):  
J. K. Lee ◽  
S. A. Hackney
Keyword(s):  
Single Phase ◽  
Lattice Misfit ◽  
Alloy System ◽  
Misfit Strain ◽  
Chemical Thermodynamics ◽  
Misfit Dislocations ◽  
Two Phase ◽  
Single Phase State ◽  
Ε Phase ◽  
Binary Alloy System

ABSTRACTThe lattice misfit strain in an overgrown island is considered to be accommodated by twodistinctive domains; a pure coherency domain (ε domain) and a domain of misfit dislocations (δ domain). By introducing such two different constituents, the model predicts the transition condition from a “single phase” state (ε phase) to a “two-phase mixture” (ε+δ) as a function of misfit strain. Further, as in the chemical thermodynamics of a binary alloy system, energy vs. misfit strain diagrams allow us to understand possible existence of various metastable states which may be associated with an overgrowth.

Microstructure Analysis of The Channel Regions in Dual Two-phase Intermetallic Alloy Based on The Ni3Al-Ni3V Pseudo-binary Alloy System

2011 ◽  
Vol 1295 ◽  
Author(s):  
T. Moronaga ◽  
Y. Kaneno ◽  
H. Tsuda ◽  
T. Takasugi
Keyword(s):  
High Temperature ◽  
Binary Alloy ◽  
Lattice Misfit ◽  
Alloy System ◽  
Dark Field ◽  
Intermetallic Alloys ◽  
Two Phase ◽  
Transmission Electron ◽  
Phase Intermetallic ◽  
Binary Alloy System

ABSTRACTDual two-phase intermetallic alloys based on the Ni3Al-Ni3V pseudo-binary alloy system have been reported to display high phase and microstructure stabilities and good mechanical properties at high temperature and are therefore considered to be used as a next generation type of high temperature structural materials. The microstructure of the dual two-phase intermetallic alloys is composed of primary Ni3Al and the channel (eutectoid) regions consisting of Ni3Al+Ni3V. In this study, the microstructure of the channel regions was investigated by a transmission electron microscope (TEM). The contrasts of the channel regions showed a complicated microstructure in bright-field images. However, the electron beam diffraction consisted of a single set of patterns and the spots did not accompany streaks, indicating that crystallographic coherency among the constituent phases or the domains is very high. It was also shown that the lattice misfit between the a-axis of Ni3Al and the c-axis of Ni3V is larger than that between the a-axis of Ni3Al and the a-axis of Ni3V. From the dark-field observation, it was found that the c-axis of Ni3V domains in the channel regions is oriented perpendicular to the interface between primary Ni3Al and Ni3V. Therefore, it is suggested that the crystallographic orientation of Ni3V in the channel regions is aligned in the manner of lowering an internal stress caused by the lattice misfit between primary Ni3Al precipitates and Ni3V domains.

Mechanisms of misfit strain relaxation in epitaxially grown BLT (Bi4-xLaxTi3O12, x = 0.75) thin films

2003 ◽  
Vol 779 ◽  
Author(s):  
Hyung Seok Kim ◽  
Sang Ho Oh ◽  
Ju Hyung Suh ◽  
Chan Gyung Park
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Strain Relaxation ◽  
Lattice Misfit ◽  
Misfit Strain ◽  
Misfit Dislocations ◽  
Transmission Electron ◽  
Means Of Transmission ◽  
20 Nm

AbstractMechanisms of misfit strain relaxation in epitaxially grown Bi4-xLaxTi3O12 (BLT) thin films deposited on SrTiO3 (STO) and LaAlO3 (LAO) substrates have been investigated by means of transmission electron microscopy (TEM). The misfit strain of 20 nm thick BLT films grown on STO substrate was relaxed by forming misfit dislocations at the interface. However, cracks were observed in 100 nm thick BLT films grown on the same STO. It was confirmed that cracks were formed because of high misfit strain accumulated with increasing the thickness of BLT, that was not sufficiently relaxed by misfit dislocations. In the case of the BLT film grown on LAO substrate, the magnitude of lattice misfit between BLT and LAO was very small (~1/10) in comparison with the case of the BLT grown on STO. The relatively small misfit strain formed in layered structure of the BLT films on LAO, therefore, was easily relaxed by distorting the film, rather than forming misfit dislocations or cracks, resulting in misorientation regions in the BLT film.

scholarly journals Investigation and application of wellbore temperature and pressure field coupling with gas–liquid two-phase flowing

2021 ◽  
Author(s):  
Jie Zheng ◽  
Yihua Dou ◽  
Zhenzhen Li ◽  
Xin Yan ◽  
Yarong Zhang ◽  
...  
Keyword(s):  
Single Phase ◽  
Phase State ◽  
Pressure Field ◽  
Coupling Model ◽  
High Water ◽  
Two Phase ◽  
Gas Well ◽  
Single Phase State ◽  
Wellbore Temperature ◽  
Temperature And Pressure

AbstractWith the development of gas well exploitation, the calculation of wellbore with single-phase state affected by single factor cannot meet the actual needs of engineering. We need to consider the simulation calculation of complex wellbore environment under the coupling of multiphase and multiple factors, so as to better serve the petroleum industry. In view of the problem that the commonly used temperature and pressure model can only be used for single-phase state under complex well conditions, and the error is large. Combined with the wellbore heat transfer mechanism and the calculation method of pipe flow pressure drop gradient, this study analyzes the shortcomings of Ramey model and Hassan & Kabir model through transient analysis. Based on the equations of mass conservation, momentum conservation and energy conservation, and considering the interaction between fluid physical parameters and temperature and pressure, the wellbore pressure coupling model of water-bearing gas well is established, and the Newton Raphael iterative method is used for MATLAB programming. On this basis, the relationship between tubing diameter, gas production, gas–water ratio, and wellbore temperature field and pressure field in high water-bearing gas wells is discussed. The results show that the wellbore temperature pressure coupling model of high water-bearing gas well considering the coupling of gas–liquid two-phase flow wellbore temperature pressure field has higher accuracy than Ramey model and Hassan & Kabir model, and the minimum coefficients of variation of each model are 0.022, 0.037 and 0.042, respectively. Therefore, the model in this study is highly consistent with the field measured data. Therefore, the findings of this study are helpful to better calculate the wellbore temperature and pressure parameters under complex well conditions.

The Effect of Alloying Elements on Microstructure and Strength Property of Dual Two-Phase Intermetallic Alloys Based on Ni3Al-Ni3V Pseudo-Binary Alloy System

2010 ◽  
Vol 654-656 ◽  
pp. 452-455
Author(s):  
K. Kawahara ◽  
T. Moronaga ◽  
Yasuyuki Kaneno ◽  
A. Kakitsuji ◽  
Takayuki Takasugi
Keyword(s):  
Alloy System ◽  
Interfacial Area ◽  
Intermetallic Alloys ◽  
Two Phase ◽  
Hardness Property ◽  
Phase Intermetallic ◽  
Binary Alloy System ◽  
Ti Addition ◽  
Solute Hardening ◽  
Additional Hardening

The microstructures and hardness property of dual two-phase intermetallic alloys that arecomposed of various kind of volume fractions of geometrically closed packed (GCP) Ni3Al(L12) and Ni3V(D022) phases were studied. The hardness of dual two-phase intermetallic alloys basically was explained by mixture rule in hardness between primary Ni3Al precipitates and eutectoid region.Nb and Ti addition raised the hardness of dual two-phase intermetallic alloys by solid solute hardening in the constituent phases.The additional hardening arising from interfacial area between primary Ni3Al precipitates and eutectoid region was also found. As temperature increases, theadditional hardening decreased for the base and Nb added alloys but decreased little for the Ti added alloys.

scholarly journals The effect of thermal agitation on atomic arrangement in alloys

1934 ◽  
Vol 145 (855) ◽  
pp. 699-730 ◽  
Keyword(s):  
Single Phase ◽  
Chemical Compounds ◽  
Alloy System ◽  
Electronic System ◽  
Atomic Ratio ◽  
The Other ◽  
Space Distribution ◽  
Binding Forces ◽  
Binary Alloy System ◽  
The One

When two metals are allowed together in various proportions, a series of solid phases is formed. A characteristic phase diagram of a binary alloy system has regions of single phase, throughout which the alloy is homogeneous, alternating with regions in which two neighbouring phases coexist. The composition of a single phase can be varied continuously over a certain range. This feature of an alloy is in contrast to tire constant atomic ratio of a chemical compound, and is explained by the nature of the binding forces in an alloy which are predominantly those between the metal atoms of both kinds on the one hand and the common electronic system on the other hand, as opposed to the binding forces between atom and atom which predominate in other chemical compounds. Not only may the atomic ratio in a given phase be varied, but also an orderly space distribution of one kind of atom relative to the other, as found in topical chemical compounds, does not necessarily exist in an alloy. Although each phase is distinguished by possessing a characteristic crystalline structure which differs from that of other phases in the same alloy system, yet this structure may be merely an orderly arrangement of sites occupied by atoms. The manner in which the atoms are distributed amongst the sites of a given phase is often variable, and is, for instance, affected by the thermal treatment which the alloy has undergone.

Interfacial and twin boundary structures of nanostructured Cu–Ag filamentary composites

2003 ◽  
Vol 18 (9) ◽  
pp. 2194-2202 ◽  
Author(s):  
K. H. Lee ◽  
S. I. Hong
Keyword(s):  
Twin Boundary ◽  
Lattice Misfit ◽  
Longitudinal Section ◽  
Copper Matrix ◽  
Misfit Strain ◽  
Boundary Structure ◽  
Misfit Dislocations ◽  
Transmission Electron ◽  
The Matrix ◽  
Twinning Shear

A high-resolution transmission electron microscope was used to study the interfacial and twin boundary structure of nanostructured Cu–Ag filamentary composites. Copper matrix and silver filaments have the orientation relationship {111}Cu∥{111}Ag and 〈111〉Cu∥〈111〉Ag. In some regions, twin bands propagated through the silver filaments with some boundary steps at the matrix/filament interface, and the silver filament appeared to be kinked in the twin band in the same direction as the twinning shear. This suggests that twins propagated after the formation of silver filament, and twin bands were deformation twins. At the matrix/filament interface, misfit interface dislocations were introduced periodically to relieve the misfit strain. The distance between interfacial misfit dislocations along the matrix/filament interface in the longitudinal section was measured to be 1.88 nm, which is in good agreement with that (1.81 nm) calculated based on lattice misfit. In Cu–Ag nanocomposites, the spacing between Moire fringes was found to be quite close to that between interfacial misfit dislocations.

Effect of compositional modification on ductility of B2 phase in Ti–Al–Nb intermetallic alloy

2002 ◽  
Vol 17 (10) ◽  
pp. 2611-2614 ◽  
Author(s):  
Feng Tang ◽  
Masuo Hagiwara
Keyword(s):  
Room Temperature ◽  
Single Phase ◽  
Phase State ◽  
Intermetallic Alloy ◽  
Chemical Compositions ◽  
Intermetallic Alloys ◽  
Two Phase ◽  
Room Temperature Ductility ◽  
Single Phase State ◽  
B2 Phase

Room-temperature ductility of two Ti–Al–Nb intermetallic alloys with close chemical compositions was investigated by tensile testing. The two alloys' ductilities in the B2 single-phase state were significantly different, which indicated that the ductility of B2 phase state was sensitive to the chemical composition. The alloy with more ductile B2 phase exhibited higher ductility in O + B2 two-phase state.

TEM observation of the channel regions in a two-phase intermetallic alloy based on Ni3Al–Ni3V pseudo-binary alloy system

2012 ◽  
Vol 21 (1) ◽  
pp. 80-87 ◽  
Author(s):  
Taku Moronaga ◽  
Yasuyuki Kaneno ◽  
Hiroshi Tsuda ◽  
Takayuki Takasugi
Keyword(s):  
Binary Alloy ◽  
Alloy System ◽  
Intermetallic Alloy ◽  
Two Phase ◽  
Phase Intermetallic ◽  
Binary Alloy System
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