Deformation of the Orthorhombic Phase in Ti-Al-Nb Alloys

1990 ◽  
Vol 213 ◽  
Author(s):  
D. Banerjee ◽  
R.G. Rowe ◽  
E.L. Hall
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Plastic Deformation ◽  
Orthorhombic Phase ◽  
Deformation Structure ◽  
Transmission Electron ◽  
Slip Planes ◽  
Dislocation Dissociation

ABSTRACTThe deformation structure of the alpha-2 and orthorhombic phase in two alloys of the Ti-Al-Nb system has been characterised by transmission electron microscopy after plastic deformation of about 2% in compression at room temperauture. The orthorhombic phase is shown to deform by all slip modes present in the alpha-2 phase. In addition, extensive “c” component slip is observed in the orthorhombic phase on slip planes that are not equivalent to those observed for “c”component slip in alpha-2. Dislocation dissociation on both basal and prismatic planes of dislocations without a c component is observed in both phases.

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.

Nanoindentation in Tin/Nbn Multilayers and Thin Films Examined Using Transmission Electron Microscopy

1999 ◽  
Vol 5 (S2) ◽  
pp. 776-777
Author(s):  
S.J. Lloyd ◽  
J.E. Pitchford ◽  
J.M. Molina-Aldareguia ◽  
Z.H. Barber ◽  
M.G. Blamire ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Deformation Structure ◽  
Tem Analysis ◽  
Repeat Distance ◽  
Cross Sectional ◽  
Thin Coatings ◽  
Transmission Electron ◽  
Salt Structure ◽  
Interesting System

Nanoindentation allows the hardness of thin coatings and synthetic multilayer structures to be measured, since indentation depths can be as little as a few 10s of nm. In combination with the cross-sectional transmission electron microscopy (TEM) analysis described here it is possible to observe the deformation structure under an indent, and potentially to understand deformation mechanisms on a nm scale in a wide variety of materials. Synthetic multilayers are a particularly interesting system to investigate. Variations in hardness with the multilayer compositional repeat distance (A) have been reported for several systems. The highest hardnesses, which are in excess of what a simple “rule of mixtures” would predict, occur in nitride multilayers at A ∼5nm. Here we present some preliminary results showing the deformation structure in both a monolithic NbN film and a TiN/NbN multilayer in which both components have the rQck salt structure with lattice parameters 0.424nm (TiN) and 0.439nm (NbN).

Plasticity and Microstructure of Irradiated Pd

1998 ◽  
Vol 540 ◽  
Author(s):  
N. Baluc ◽  
Y. Dai ◽  
M. Victoria
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Plastic Deformation ◽  
Ambient Temperature ◽  
Tensile Deformation ◽  
Microscopic Level ◽  
Macroscopic Scale ◽  
Slip Bands ◽  
Transmission Electron ◽  
Mev Protons

AbstractSingle crystalline specimens of pure Pd have been irradiated at ambient temperature with 590 MeV protons to doses ranging between 10−4 and 10−1 dpa. Tensile deformation experiments revealed that irradiation induces hardening and embrittlement, while scanning (SEM) and transmission electron microscopy (TEM) observations showed that plastic deformation of specimens irradiated to a dose ≥ 10−2 dpa is strongly localized and yields the creation of slip bands at the macroscopic scale and of defect-free channels at the microscopic level.

Hydrogen induced plastic deformation of stainless steel

1998 ◽  
Vol 513 ◽  
Author(s):  
V. J. Gadgil ◽  
E. G. Keima ◽  
H. J. M. Geijselaers
Keyword(s):  
Electron Microscopy ◽  
Finite Element Method ◽  
Transmission Electron Microscopy ◽  
Computer Simulation ◽  
Plastic Deformation ◽  
Stainless Steel ◽  
Cross Section ◽  
Dislocation Substructure ◽  
Transmission Electron ◽  
Aqueous Environments

ABSTRACTHydrogen can influence the behaviour of materials significantly. The effects of hydrogen are specially pronounced in high fugacities of hydrogen which can occur at the surface of steels in contact with certain aqueous environments. In this investigation the effect of high fugacity hydrogen on the surface of stainless steel was investigated using electrochemical cathodic charging. Microhardness was measured on the cross section. Transmission electron microscopy was used to investigate the dislocation substructure just below the surface. Computer simulation using finite element method was carried out to estimate the extent and severity of the deformation. The significance of the results are discussed in relation to the loss of ductility due to hydrogen.

Microstructure and Indentation Fracture of Dysprosium Niobate

2005 ◽  
Vol 20 (6) ◽  
pp. 1422-1427 ◽  
Author(s):  
Byong-Taek Lee ◽  
Waltraud M. Kriven
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Plastic Deformation ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Indentation Fracture ◽  
Optical Scanning ◽  
Periodic Arrays ◽  
Transmission Electron ◽  
Hot Hardness

The high-temperature indentation fracture and microstructures of dysprosium niobate (DyNbO4) were investigated by optical, scanning, and transmission electron microscopy (OM, SEM, and TEM). Polycrystalline samples were sintered at 1350 °C for 3 h and cut into 3 mm disks for TEM. The disks were indented in a Nikon QM (Tokyo, Japan) hot hardness indenter at room temperature up to 1000 °C. Many lamellar twins having different widths were observed by TEM as well as intergranular microcracks. The room temperature hardness was relatively low at 5.64 GPa and decreased with elevated temperatures. Crack lengths were short, showing a typical micro-cracking effect. In the sample indented at 1000 °C, dislocations in periodic arrays were evident, and their density increased markedly due to heavy plastic deformation.

Plasticity of decagonal Al73Ni10Co17 quasicrystals

2003 ◽  
Vol 805 ◽  
Author(s):  
Peter Schall ◽  
Michael Feuerbacher ◽  
Knut Urban
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Plastic Deformation ◽  
Deformation Mechanisms ◽  
Compression Tests ◽  
Compression Axis ◽  
Decagonal Quasicrystal ◽  
Transmission Electron ◽  
Axis Parallel ◽  
Means Of Transmission

ABSTRACTWe present a study of the deformation mechanism of decagonal Al73Ni10Co17 quasicrystals by means of transmission electron microscopy. We performed compression tests on single-quasicrystalline samples in three different orientations: with the compression axis parallel to, inclined by 45 ° and perpendicular to the tenfold axis of the decagonal quasicrystal. The deformed samples reveal characteristic orientation-dependent dislocation structures leading us to the conclusion that fundamentally different deformation mechanisms are involved in plastic deformation in the three deformation geometries. We explicitly identified the Burgers vectors of the dislocations as interatomic vectors in the structure of decagonal Al-Ni-Co.

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