Metastable Phases and Defect Microstructures in Melt-Spun Ribbons of Nb3Al

1990 ◽  
Vol 209 ◽  
Author(s):  
M. Aindow ◽  
J. Shyue ◽  
T.A. Gaspar ◽  
H.L. Fraser
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Nominal Composition ◽  
Partial Dislocations ◽  
Transmission Electron ◽  
Melt Spun ◽  
B2 Phase ◽  
Melt Spun Ribbons ◽  
Defect Microstructures ◽  
A15 Phase

ABSTRACTThe phases and defects produced in a binary alloy, with nominal composition Nb-18at.% Al, have been studied using transmission electron microscopy (TEM). In addition to the equilibrium A15 phase (Nb3Al) a previously unreported Nb-rich B2 phase is present. A significant number of grow-in dislocations were observed in the A15 phase, these have b= a<100> and are predominantly screw on character. They are dissociated into two partial dislocations which bound a stacking fault according to the reaction;<100> → > 1/2 <100> + SF + 1/2 <100>The habit plane of the fault is shown to be {012}. These observations are compared with previous studies performed on the isostructual compound V3Si. The consequences of the observed dissociation for the plastic deformation of Nb3Al are discussed.

scholarly journals Alloy Design, Thermodynamics, and Electron Microscopy of Ternary Ti-Ag-Nb Alloy with Liquid Phase Separation

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5268
Author(s):  
Takeshi Nagase
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Phase Separation ◽  
Liquid Phase ◽  
Alloy System ◽  
Liquid Phase Separation ◽  
Mixing Enthalpy ◽  
Transmission Electron ◽  
Melt Spun ◽  
Melt Spun Ribbons

The Ti–Ag alloy system is an important constituent of dental casting materials and metallic biomaterials with antibacterial functions. The binary Ti–Ag alloy system is characterized by flat liquidus lines with metastable liquid miscibility gaps in the phase diagram. The ternary Ti–Ag-based alloys with liquid phase separation (LPS) were designed based on the mixing enthalpy parameters, thermodynamic calculations using FactSage and Scientific Group Thermodata Europe (SGTE) database, and the predicted ground state diagrams constructed by the Materials Project. The LPS behavior in the ternary Ti–Ag–Nb alloy was investigated using the solidification microstructure analysis in arc-melted ingots and rapidly solidified melt-spun ribbons via trans-scale observations, combined with optical microscopy (OM), scanning electron microscopy (SEM) including electron probe micro analysis (EPMA), transmission electron microscopy (TEM), and scanning transmission electron microscopy (STEM). The solidification microstructures depended on the solidification processing in ternary Ti–Ag–Nb alloys; macroscopic phase-separated structures were observed in the arc-melted ingots, whereas fine Ag globules embedded in the Ti-based matrix were observed in the melt-spun ribbons.

Transmission electron microscopy studying of structural features of NiTi B2 phase formed under pulsed electron-beam impact

2015 ◽  
Author(s):  
Ludmila L. Meisner ◽  
Alexey A. Neiman ◽  
Alexander I. Lotkov ◽  
Nikolai N. Koval ◽  
Viktor O. Semin ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Beam ◽  
Structural Features ◽  
Pulsed Electron Beam ◽  
Transmission Electron ◽  
B2 Phase

Dislocations and stacking faults in stainless steel

1957 ◽  
Vol 240 (1223) ◽  
pp. 524-538 ◽  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Stainless Steel ◽  
Grain Boundaries ◽  
Stacking Faults ◽  
Stacking Fault ◽  
Stacking Fault Energy ◽  
Thin Sections ◽  
Partial Dislocations ◽  
Transmission Electron

Further experiments by transmission electron microscopy on thin sections of stainless steel deformed by small amounts have enabled extended dislocations to be observed directly. The arrangement and motion of whole and partial dislocations have been followed in detail. Many of the dislocations are found to have piled up against grain boundaries. Other observations include the formation of wide stacking faults, the interaction of dislocations with twin boundaries, and the formation of dislocations at thin edges of the foils. An estimate is made of the stacking-fault energy from a consideration of the stresses present, and the properties of the dislocations are found to be in agreement with those expected from a metal of low stacking-fault energy.

New method for the production of bulk amorphous materials of Nd–Fe–B alloys

2005 ◽  
Vol 20 (3) ◽  
pp. 563-566 ◽  
Author(s):  
Tetsuji Saito ◽  
Hiroyuku Takeishi ◽  
Noboru Nakayama
Keyword(s):  
Electron Microscopy ◽  
Amorphous Materials ◽  
Room Temperature ◽  
Amorphous Structure ◽  
X Ray Diffraction ◽  
Bulk Materials ◽  
X Ray ◽  
Transmission Electron ◽  
Melt Spun ◽  
Melt Spun Ribbons

We report a new compression shearing method for the production of bulk amorphous materials. In this study, amorphous Nd–Fe–B melt-spun ribbons were successfully consolidated into bulk form at room temperature by the compression shearing method. X-ray diffraction and transmission electron microscopy studies revealed that the amorphous structure was well maintained in the bulk materials. The resultant bulk materials exhibited the same magnetic properties as the original amorphous Nd–Fe–B materials.

EFFECT OF NANOCRYSTALLIZATION ANNEALING ON MAGNETIC PROPERTIES AND MAGNETOIMPEDANCE OF CO-BASE RIBBONS

2012 ◽  
Vol 05 ◽  
pp. 841-846
Author(s):  
AMIR KEYVANARA ◽  
REZA GHOLAMIPOUR ◽  
SHAMSEDIN MIRDAMADI ◽  
FARZAD SHAHRI ◽  
HOSSEIN SEPEHRI AMIN
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Magnetic Properties ◽  
Structural Studies ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Melt Spun ◽  
Melt Spun Ribbons ◽  
Nanocrystalline Phases

Melt spun ribbons of Co 64 Fe 4 Ni 2 B 19 Si 8 Cr 3 alloy have been prepared and the nanocrystallization process was carried out by the heat treatment of the as spun ribbons above the crystallization temperature. Structural studies of the samples have been performed by transmission electron microscopy and X-ray diffraction. Magnetic properties of the samples and magnetoimpedance measurements were investigated and it was revealed that magnetic properties and magnetoimpedance of the samples deteriorate by the formation of nanocrystalline phases.

Precipitate Crystal Structure Determination in Melt Spun Mg-1.5wt%Ca-6wt%Zn Alloy

2002 ◽  
Vol 8 (6) ◽  
pp. 487-496 ◽  
Author(s):  
Paula M. Jardim ◽  
Guillermo Solórzano ◽  
John B. Vander Sande
Keyword(s):  
Crystal Structure ◽  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution Electron Microscopy ◽  
Precipitate Crystal ◽  
Transmission Electron ◽  
Melt Spun ◽  
Scanning Transmission ◽  
Boundary Films ◽  
Zn Alloy

A melt-spun Mg-1.5%wtCa-6wt%Zn alloy was analyzed by means of transmission electron microscopy, energy dispersive X-ray spectroscopy, and scanning transmission electron microscopy. The as-solidified alloy exhibited both spherical matrix precipitates and elongated precipitates at the grain boundaries (grain-boundary films). After heat treatment, the alloy showed faceted precipitates (cuboidal shape), mostly on dislocations. It was found that the observed precipitates are the same compound, Ca2Mg6Zn3. As there was no crystallographic data for this compound in the literature, its crystal structure was investigated by comparison of experimental and simulated selected-area electron-diffraction patterns and high-resolution electron microscopy images. This study indicated that Ca2Mg6Zn3 is a trigonal compound with space group P31c and lattice parameters a = 0.97 nm, c = 1.0 nm.

The Observations on Faulted Dipoles in Deformed Tial—Based Alloys

1994 ◽  
Vol 364 ◽  
Author(s):  
Y. Gao ◽  
J. Zhu ◽  
Q. G. Cai
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Plastic Deformation ◽  
Low Temperature ◽  
Deformation Temperature ◽  
Room Temperature ◽  
Single Phase ◽  
Deformation Structure ◽  
Partial Dislocations ◽  
Transmission Electron

AbstractThe deformation structure of polycrystalline TiAl-based alloys after uniaxial compression at temperature range from 77K to 1073K has been examined using transmission electron microscopy. It was observed that a large number of faulted dipoles are commonly present in deformation structure of the alloys compressed at low temperature 77K and room temperature. The nature of the faulted dipoles has been determined to be intrinsic stacking fault lying on {111} plane, bounded by 1/6<112] partial dislocations. A possible mechanism for the formation of the faulted dipoles was suggested. The results of the statistic observation shows that faulted dipoles in deformed Ti-48A1 and Ti-(47–48) Al-X (X = V,Cr,Mn) alloys are less than those in single phase Ti-52A1 alloy, and the number of the faulted dipoles decreases with increasing deformation temperature. The effect of the faulted dipoles on plastic deformation of the alloy was discussed.

Dynamical Study of Dislocations and 4H → 3C Transformation Induced by Stress in (11-20) 4H-SiC

2005 ◽  
Vol 483-485 ◽  
pp. 299-302 ◽  
Author(s):  
Hosni Idrissi ◽  
Maryse Lancin ◽  
Joel Douin ◽  
G. Regula ◽  
Bernard Pichaud
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Chemical Etching ◽  
Stacking Faults ◽  
Sample Surface ◽  
Cubic Phase ◽  
Dynamical Study ◽  
Weak Beam ◽  
Partial Dislocations ◽  
Transmission Electron

4H-SiC samples were bent in compression mode at temperature ranging from 400°C to 700°C. The introduced-defects were identified by Weak Beam (WB) and High Resolution Transmission Electron Microscopy (HRTEM) techniques. They consist of double stacking faults bound by 30° Si(g) partial dislocations whose glide locally transforms the material in its cubic phase. The velocity of partial dislocations was measured after chemical etching of the sample surface. The formation and the expansion of the double stacking faults are discussed.

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