摘要:

The strain-rate and temperature dependence of the lower yield stress of silicon and several III-V compounds is different for as-grown and pre-deformed crystals. While the behaviour of as-grown material is rather uniform among these semiconductors, a pre-deformation of the specimens gives rise to various effects. Intrinsic and deformation-induced point defects clustering into small voids and precipitates may be responsible for such differences.

ISSN:0950-0839    

DOI:10.1080/09500839208206006

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The technique of reflection electron microscopy has been applied to the imaging of GaAs/Alx,Ga1−xAs multilayer materials. The image contrast of the multilayer materials is shown to result mainly from the composition variation across the structures. We demonstrated that, by using surface resonance effects, an GaAs/AlxGa1−xAs epitaxial layer with 1·0% Al can be identified, and a multiplequantum-well structure with periodicity down to 20 Å can be imaged.

ISSN:0950-0839    

DOI:10.1080/09500839208206007

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A new type of decagonal phase having superlattice order has been found in an AI70Ni15Co15alloy by means of the electron diffraction technique. Most of the grains in the Al70Ni15Co15sample heat treated at 600°C for 216h exhibit superlattice order. In contrast, superlattice order has not been seen for the Al65Cu20Co15decagonal phase. The relation between the structures with and without superlattice order is discussed using a four-dimensional description of the decagonal quasicrystalline structure.

ISSN:0950-0839    

DOI:10.1080/09500839208206008

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

X-ray microanalysis using an analytical electron microscope equipped with a cold field emission gun has been applied to the detection of the Suzuki segregation of solute atoms onto the stacking faults of extended dislocations in a Cu–Si alloy. Direct evidence for Suzuki segregation has been obtained.

ISSN:0950-0839    

DOI:10.1080/09500839208206009

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Micron-sized pockets of liquid metals entrapped in a metal matrix have served to elucidate undercooling behaviour and have long been employed to determine the solid–liquid interfacial energies. The model of Young and Clyne for liquation has been used to design a suitable heat treatment cycle to produce progressively finer sizes of liquid pockets. Results on an Ag–14at.%Ge alloy confirm the model.

ISSN:0950-0839    

DOI:10.1080/09500839208206010

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A comparison has been made of the defect image contrast obtained using conventional two-beam dark-field and the bright-field down-zone techniques. It is shown that better resolution and contrast of isolated amorphous zones in GaAs and vacancy loops in a Ag–Pd alloy are obtained in the down-zone images.

ISSN:0950-0839    

DOI:10.1080/09500839208206011

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The {100} platelets of a type IaA/B diamond have been examined by spatially resolved electron-energy-loss spectroscopy. It is demonstrated unambiguously that nitrogen is present at these planar defects but in low concentrations. A quantitative analysis of the data reveals that the atomic density of the nitrogen is 0·23 (±0·14)atoms pera20, that is about one tenth of a monolayer. This amount is significantly less than predicted by the nitrogen-containing structural models. It is concluded that the platelets are most likely to be composed of carbon and contain nitrogen as a major impurity species.

ISSN:0950-0839    

DOI:10.1080/09500839208206012

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor