Transmission electron microscopy of dislocation dissociations and stacking faults in γ′-hardened nickel-base superalloys

1992 ◽  
Vol 65 (6) ◽  
pp. 1383-1394 ◽  
Author(s):  
K. Trinckauf ◽  
E. Nembach
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Stacking Faults ◽  
Transmission Electron ◽  
Nickel Base Superalloys ◽  
Nickel Base

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.

Structural Characterization of CF-PVT Grown Bulk 3C-SiC

2008 ◽  
Vol 600-603 ◽  
pp. 67-70 ◽  
Author(s):  
Alkyoni Mantzari ◽  
Frédéric Mercier ◽  
Maher Soueidan ◽  
Didier Chaussende ◽  
Gabriel Ferro ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Structural Properties ◽  
Structural Characterization ◽  
Stacking Faults ◽  
Vapor Transport ◽  
Physical Vapor Transport ◽  
Transmission Electron ◽  
Continuous Feed

The aim of the present work is to study the structural properties of 3C-SiC which is grown on (0001) 6H-SiC and on (100) 3C-SiC (Hoya) seeds using the Continuous Feed Physical Vapor Transport (CF-PVT) method. Transmission Electron Microscopy (TEM) observations confirm that the overgrown layer is of the 3C-SiC polytype. In the case of the 6H-SiC substrate, microtwins (MTs), stacking faults (SFs) and dislocations (D) are observed at the substrate-overgrown interface with most of the dislocations annihilating within the first few µm from the interface. In the case of 3C-SiC crystals grown on 3C seeds, repeated SFs are formed locally and also coherent (111) twins of 3C-SiC are frequently observed near the surface. The SF density is reduced at the uppermost part of the grown material.

Deformation of Monocrystalline Silicon under Nanoscratching

2008 ◽  
Vol 41-42 ◽  
pp. 15-19 ◽  
Author(s):  
Y.Q. Wu ◽  
Han Huang ◽  
Jin Zou
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Applied Load ◽  
Normal Load ◽  
Stacking Faults ◽  
Monocrystalline Silicon ◽  
Crystalline Region ◽  
Density Of Dislocations ◽  
Transmission Electron ◽  
Amorphous Si

In this work, deformation of monocrystalline silicon (Si) under nanoscratching was investigated using transmission electron microscopy (TEM). The results indicated that no fracture occurred during nanoscratching with loads ranging from 1 to 6 mN. The damaged regions induced by nanoscratching included an amorphous Si region and a damaged crystalline Si region. Detailed TEM analyses revealed that at the lowest load of 1 mN no dislocation was observed in the damaged crystalline region, and only stacking faults were observed at the boundary between the damaged crystalline Si and amorphous Si. Dislocations started to nucleate along (111) planes and penetrated into the bulk Si when the normal load was increased to 2 mN and above. Defects perpendicular to the scratched surface were initiated when the load was greater than 4 mN. The density of dislocations also increased rapidly with the increase of the applied load.

Morphology of Precipitates in Ni-Al-Cr Intermetallic Alloy

2007 ◽  
Vol 130 ◽  
pp. 159-162
Author(s):  
Mirosław Pilawa ◽  
Elżbieta Jezierska
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Intermetallic Alloy ◽  
Nickel Base Superalloy ◽  
Transmission Electron ◽  
Characteristic Features ◽  
Secondary Precipitates ◽  
Nickel Base ◽  
Base Superalloy

Transmission electron microscopy was used to study various morphologies of ordered precipitates in Ni3Al-Cr intermetallic alloy. It was found that γ’ precipitates in the interdendritic regions have the microstructure of a nickel base superalloy with its characteristic features. In addition to the primary γ’ precipitates some fine secondary precipitates were found.

TEM Study of Mg-Doped Bulk GaN Crystals

1999 ◽  
Vol 572 ◽  
Author(s):  
Z. Liliental-Weber ◽  
M. Benamara ◽  
S. Ruvimov ◽  
J. H. Mazur ◽  
J. Washburn ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Growth Rate ◽  
Stacking Faults ◽  
High Energy ◽  
Defect Distribution ◽  
Transmission Electron ◽  
Bulk Gan ◽  
Shed Light ◽  
Mg Doped

ABSTRACTTransmission electron microscopy was applied to cross-sectioned samples to study surface morphology, sample polarity and defect distribution in bulk GaN samples doped with Mg. These crystals were grown from a Ga melt under high hydrostatic pressure of Nitrogen. It was shown that the types of defects and their distribution along the c-axis depends strongly on sample polarity. Based on this finding the growth rate along the c-axis for the two polar directions was compared and shown to be approximately ten times larger for Ga polarity than for N-polarity. In the part of the crystals with Ga polarity pyramidal defects with a base consisting of high energy stacking faults were found. The parts of the crystals grown with Npolarity were either defect free or contained regularly spaced stacking faults. Growth of these regularly spaced cubic monolayers is polarity dependent; this structure was formed only for the growth with N polarity and only for the crystals doped with Mg. Formation of this superstructure is similar to the polytypoid structure formed in AlN crystals rich in oxygen. It is also likely that oxygen can decorate the cubic monolayers and compensate Mg. This newly observed structure may shed light on the difficulties of p-doping in GaN:Mg.

Polytypoids in high Tc thallium based superconducting materials

1990 ◽  
Vol 5 (8) ◽  
pp. 1620-1624
Author(s):  
A. K. Singh ◽  
M. A. Imam ◽  
K. Sadananda ◽  
S. B. Qadri ◽  
E. F. Skelton ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Diffraction ◽  
Diffraction Pattern ◽  
Electron Diffraction Pattern ◽  
Stacking Faults ◽  
Superconducting Materials ◽  
Superconducting Properties ◽  
High Tc ◽  
Transmission Electron

Several high Tc compounds containing Tl (thallium) were prepared starting from different initial compositions. Superconducting properties and the structure were determined for each sample. Electron diffraction and transmission electron microscopy showed the existence of polytypic high Tc compounds with the same a- and b-axes but different c-axis values. The c-axis appears to increase approximately in integral multiples of 0.15 nm with varying composition and is associated with the insertion of Cu–Ca or Cu–Tl layers in each unit cell. Several random stacking faults were also noted, which give rise to diffuse streaking in the electron diffraction pattern.

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