A Transmission Electron Microscope Study of Hardness Indentations in MoSi2

2000 ◽  
Vol 15 (4) ◽  
pp. 1025-1032 ◽  
Author(s):  
P. H. Boldt ◽  
G. C. Weatherly ◽  
J. D. Embury
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope Study ◽  
Room Temperature ◽  
Slip Systems ◽  
Cavity Model ◽  
Dislocation Loops ◽  
Density Of Dislocations ◽  
Transmission Electron ◽  
Large Rotations ◽  
Transmission Electron Microscope Study

Transmission electron microscopy and electron diffraction were used to study hardness indentations made at room temperature in ⟨001⟩-oriented single crystals of MoSi2. Two families of slip systems, {110}⟨001⟩ and {101}⟨010⟩, were identified. The first system formed ⟨001⟩ dislocation loops by prismatic punching beneath the indenter, while the second system led to large rotations of the crystal lattice beneath the indenter. The lattice rotations were used to estimate the density of dislocations stored in this volume. The results demonstrate that the hardness response of MoSi2 can be explained by the expanding cavity model with most of the plastic accommodation occurring immediately beneath the indenter.

Transmission Electron Microscope Study of Interfacial Reactions in Gold-Germanium Contact to Gallium Arsenide

1985 ◽  
Vol 54 ◽  
Author(s):  
Taeil Kim ◽  
D.D.L. Chung
Keyword(s):  
Electron Microscopy ◽  
Solid Solution ◽  
Transmission Electron Microscopy ◽  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Electron Microscope Study ◽  
Lattice Match ◽  
Perfect Lattice ◽  
Transmission Electron ◽  
Transmission Electron Microscope Study

ABSTRACTThe structure of 500 Å Au/500 A Ge/500 Å Au/GaAs (100) was studied by transmission electron microscopy after annealing at 350 – 500°C. Annealing at 350 – 450°C caused the formation of AuGeAs with a (110) texture, but this phase disappeared after annealing at 500°C. The hexagonal a-AuGa (or AuGa) was formed after annealing at 400°C, such that (111)Au // (0001)a, and [110]AU // [1120]a and there was perfect lattice match between Au (i.e., Au-rich solid solution) and a-AuGa. After annealing at 450°C or above, a phase tentatively identified as the hexagonal Au3Ga was formed and Ge (i.e., Ge-rich solid solution) became epitaxial to (100) GaAs. Annealing at 400°C caused Au to change from no texture to a (110) texture.

The Effect of Cryorolling on the Microstructure of Al-Cu-Mg Alloy

2016 ◽  
Vol 877 ◽  
pp. 188-193 ◽  
Author(s):  
Li Wei Quan ◽  
Wen Ning Mu ◽  
Lei Kang ◽  
Xiao Ma ◽  
Peng Han ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Tensile Strength ◽  
Yield Strength ◽  
Optical Microscopy ◽  
Room Temperature ◽  
Solution Treatment ◽  
Mg Alloy ◽  
Dislocation Loops ◽  
Transmission Electron

A precipitation hardenable Al-Cu-Mg alloy was cryorolled with liquid nitrogen followed solution treatment and then aged at 170 ̊C for different time. The microstructure was characterized by optical microscopy (OM) and transmission electron microscopy (TEM). Hardness and tensile strength were also tested. The dislocation loops in the cryorolled alloy are more than the room temperature rolled alloy. Meanwhile the hardness, yield strength and tensile strength are larger than the room temperature rolled alloy.

High Resolution Transmission Electron Microscope Study of Amorphous and Partially Crystalline Fe7 8B1 3Si9 Alloy

1985 ◽  
Vol 58 ◽  
Author(s):  
A.R. Bhatti ◽  
J.C. Barry ◽  
B Cantor
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Electron Microscope Study ◽  
Lattice Imaging ◽  
Transmission Electron ◽  
Different Types ◽  
Mean Size ◽  
Transmission Electron Microscope Study ◽  
Imaging Mode

ABSTRACTAmorphous and partially crystalline Fe7 8B1 3 Si9 alloys have been examined by high resolution transmission electron microscopy at 200kV. In lattice imaging mode, the as-quenched alloy shows small regions, with a mean size of - 20Å, consisting of well defined patterns of fringes. Three different types of crystals can be identified at the very earliest stages of crystallisation of the alloy.

Plastic Deformation of Ti3Al and Ti3Al/TiA1 Polycrystals

1988 ◽  
Vol 133 ◽  
Author(s):  
S. A. Court ◽  
J. P. A. Löfvander ◽  
M. A. Stucke ◽  
P. Kurath ◽  
H. L. Fraser
Keyword(s):  
Electron Microscopy ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Covalent Bonding ◽  
Relative Activity ◽  
Slip Systems ◽  
Dislocation Mobility ◽  
Two Phase ◽  
Influence Of Temperature ◽  
Transmission Electron

ABSTRACTSamples of polycrystalline Ti3Al-base alloys, and a two phase Ti3Al/TiAl mixture have been deformed at room temperature and at elevated temperatures and examined subsequently by transmission electron microscopy in order to determine the influence of temperature and alloy content on the relative activity of the various slip systems. In particular, the detailed influence of covalent bonding on dislocation mobility in Ti3Al has been identified.

The Microstructure of Transiently Annealed Donor Implants in GaAs

1984 ◽  
Vol 35 ◽  
Author(s):  
M.A. Shahid ◽  
R. Bensalem ◽  
B.J. Sealy
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electrical Activity ◽  
Room Temperature ◽  
Dislocation Loops ◽  
Electrical Measurements ◽  
Ion Energy ◽  
Transmission Electron

ABSTRACTUndoped SI (100) GaAs has been implanted with selenium and tin ions at room temperature at an ion energy of 300 keV and using ion dose in the range 1 × 1014 to 1 × 1015 ions cm−2. Transient annealing at 1000°C and above has been studied using electrical measurements and transmission electron microscopy. The results show that tin implanted samples have comparatively higher values of electrical activity and mobility than those implanted with selenium ions. A difference in the microstructure of these two implants was observed. Selenium implanted samples show dislocation lines and loops possessing 1/2<110> Burgers vectors while tin implanted GaAs contains dislocation loops of 1/2<110> and 1/3<111> types and also dislocation lines having 1/2<110> Burgers vectors. Both types of defect in tin implanted samples are decorated with precipitates.

Martensitic Nucleation in Small ZrO2 Particles

1985 ◽  
Vol 57 ◽  
Author(s):  
I-Wei Chen ◽  
Yi-Hung Chiao
Keyword(s):  
Thin Film ◽  
Electron Microscopy ◽  
Room Temperature ◽  
Equilibrium Temperature ◽  
Dislocation Loops ◽  
Spontaneous Transformation ◽  
Transmission Electron ◽  
Free Particles ◽  
Martensitic Nucleation

AbstractSmall ZrO2 particles were studied by in-situ transmission electron microscopy and the types of events which led to martensitic nucleation were recorded. These metastable particles were single crystals of several hundred nanometers size and were supported on a carbon thin film but were otherwise free from any constraint. At room temperature, they are more than 1200°C below the equilibrium temperature. After dislocation loops were injected in-situ into the originally defect-free particles, a critical loop size was found beyond which the particle transformed spontaneously. It was also observed that Hertzian contacts between two particles led to martensitic nucleation and spontaneous transformation. These results were satisfactorily rationalized by ab-initio theoretical analysis.

Twinning Accommodation in Highly Aligned Superconducting YBa2Cu307-x

1989 ◽  
Vol 42 (4) ◽  
pp. 419 ◽  
Author(s):  
JP Zhou ◽  
CC Sorrell ◽  
SX Dou ◽  
AJ Bourdillon
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Room Temperature ◽  
Thermal Stresses ◽  
Slip Systems ◽  
Transmission Electron ◽  
Formation Of Cracks ◽  
Multiple Twinning ◽  
Material Formation

Defects in the form of twins, slips, kinks and cracks have been studied at room temperature by transmission electron microscopy. In highly aligned YBa2Cu307-x, multiple twinning can be observed, where the orientation of twin planes is varied by accommodation by slipping and kinking. Suitable (TIO) {1l0} slip systems are able to occur in this material. Formation of cracks on subgrain boundaries may occur after twinning in order to relieve transformational and thermal stresses.

High Resolution Transmission Electron Microscopy of Defect Clusters in Aluminum During Electron and Ion Irradiation at Room Temperature

1996 ◽  
Vol 439 ◽  
Author(s):  
Kazuo Furuya ◽  
Min Piao ◽  
Nobuhiro Ishikawa ◽  
Tetsuya Saito
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Room Temperature ◽  
Ion Irradiation ◽  
In Situ Observation ◽  
Dislocation Loops ◽  
Frank Loop ◽  
Planar Defects ◽  
Defect Clusters ◽  
Transmission Electron

AbstractDefect clusters in Al during electron and ion irradiation have been investigated using highresolution transmission electron microscopy (HRTEM). An ION/HVEM system which consists of a high-voltage TEM and ion implanters was used for in-situ observation of damage evolution under 1000 keV electrons and 15 keV He+ irradiation at room temperature. HRTEM of Al in [110] orientation showed many planar defects along { 111 } planes during electron irradiation, while a high density of small polyhedron-shaped cavities (He-bubbles) was observed in addition to the planar defects after He+ irradiation. Multi-slice image simulation of various models of dislocation loops indicated the planar defect as an interstitial-type Frank loop.

High dose neutron irradiation damage in alpha alumina

1991 ◽  
Vol 6 (10) ◽  
pp. 2178-2187 ◽  
Author(s):  
R.A. Youngman ◽  
T.E. Mitchell ◽  
F.W. Clinard ◽  
G.F. Hurley
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Void Formation ◽  
High Density ◽  
Irradiation Damage ◽  
High Dose ◽  
Dislocation Loops ◽  
Density Of Dislocations ◽  
Transmission Electron ◽  
Alpha Alumina

Bulk samples of single crystalline and polycrystalline alpha alumina have been neutron-irradiated in the Experimental Breeder Reactor-II (EBR-II) to doses of 1026 n/m2 at temperatures of 925 K and 1100 K. The samples were found to swell macroscopically between 3% and 6%, depending on the temperature of irradiation and the form of the material. The damaged microstructures were investigated via transmission electron microscopy in order to understand the origin of the macroscopic swelling. In both single crystals and polycrystals the damage consists of a high density of dislocations containing predominately b = 1/3<101> dislocation loops on the (0001) planes coexistent with a high density of voids, which are aligned along the c-axis in this rhombohedral material. The established theory of void formation in metals is utilized to explain the formation of voids in alumina. The polycrystalline samples were extensively microcracked, and this is thought to be due to anisotropic swelling of the grains which in turn leads to stresses and fracturing at the grain boundaries.

Annealing Of Radiation Damage in Tungsten

1970 ◽  
Vol 28 ◽  
pp. 412-413
Author(s):  
Robert C. Rau ◽  
John Moteff
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Radiation Damage ◽  
Thermal Annealing ◽  
Neutron Fluence ◽  
Dislocation Loops ◽  
Defect Clusters ◽  
Polycrystalline Tungsten ◽  
Transmission Electron ◽  
Radiation Induced

Transmission electron microscopy has been used to study the thermal annealing of radiation induced defect clusters in polycrystalline tungsten. Specimens were taken from cylindrical tensile bars which had been irradiated to a fast (E > 1 MeV) neutron fluence of 4.2 × 1019 n/cm2 at 70°C, annealed for one hour at various temperatures in argon, and tensile tested at 240°C in helium. Foils from both the unstressed button heads and the reduced areas near the fracture were examined.Figure 1 shows typical microstructures in button head foils. In the unannealed condition, Fig. 1(a), a dispersion of fine dot clusters was present. Annealing at 435°C, Fig. 1(b), produced an apparent slight decrease in cluster concentration, but annealing at 740°C, Fig. 1(C), resulted in a noticeable densification of the clusters. Finally, annealing at 900°C and 1040°C, Figs. 1(d) and (e), caused a definite decrease in cluster concentration and led to the formation of resolvable dislocation loops.

Sign in / Sign up

Export Citation Format

Share Document