摘要:

The role of kinks in moving locked screw superdislocations in L12alloys is studied. In Ni3Al single crystals deformed at room temperature, two types of kinks are identified: single kinks that sit on one superpartial and paired ones. It is shown that both types glide on the primary octahedral plane and interconnect screw superdislocations which are themselves dissociated in the cube cross-slip plane. A geometrical glissile model for the kink is proposed.

ISSN:0950-0839    

DOI:10.1080/09500839008206364

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Clean surfaces of a Tb4O7crystal have been investigated on the atomic scale by a surface profile imaging technique. The formation of a 60° mixed dislocation due to electron irradiation on the (111) surface is observed in situ.

ISSN:0950-0839    

DOI:10.1080/09500839008206365

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

ZnSe films grown on (100) Ge substrates by molecular beam epitaxy (MBE) contain a high density of defects such as twins and, in some instances, low-angle boundaries. In situ transmission electron microscopy (TEM) annealing and bulk vacuum annealing studies have been made on as-grown ZnSe/(100)Ge specimens. For both kinds of annealing, the twins were found to be very stable during heating–cooling cycles.

ISSN:0950-0839    

DOI:10.1080/09500839008206366

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

We have observed a spiral-shaped buckling of phosphorus-doped hydrogenated amorphous silicon(a-Si: H) films deposited on glass and on crystalline Si substrates. The spiral pattern has a wavelength of 0·02 cm and develops at a speed of about 0·01 cm min−1. The buckling effect can be initiated by mechanical perturbation. The cross-section of the bulge is an arch with a height of 4·5–6 μm and a span of 100 μm. This kind of buckling is observed in 1 pm thick films having internal compressional stress exceeding about 6 × 109dyne cm−2.

ISSN:0950-0839    

DOI:10.1080/09500839008206367

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

High-resolution electron microscopy has been used to study the atomic structure of twins in the binary oxide CuAlO2. This compound is an occasional product of the bonding between pre-oxidized copper and alumina; its peculiarity is to exhibit a twinned microstructure, owing to the occurrence of two enantiomorphic right- and left-handed configurations. The microstructural examination at high resolution reveals that twin planes are located on copper basal planes rather than aluminium planes; this result is discussed on the basis of an analysis of the various possible stacking sequences which can reasonably be considered to occur at the twin interfaces.

ISSN:0950-0839    

DOI:10.1080/09500839008206368

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

In a recent paper, Mott associates an approximateT1/2variation of conductivity in InP near the metal–insulator transition with the Altshuler and Aronov electron interaction theory. This interpretation requires some rather surprising parameter values. In this Letter we offer an alternative explanation which avoids these difficulties.

ISSN:0950-0839    

DOI:10.1080/09500839008206369

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The study of crystallization processes of rapidly solidified alloys by means of high-resolution electron microscopy and isothermal calorimetry measurements can help to resolve the long-standing controversies between the amorphous and microcrystalline models in metallic glasses. Close examination of a melt-spun Al90Fe5Gd5alloy based on these techniques shows that the structural nature of this new family of aluminium-based metallic glasses is truly amorphous, rather than microcrystalline. Based on our calorimetric measurements, the unusual formability of aluminium-rich metallic glasses is also discussed.

ISSN:0950-0839    

DOI:10.1080/09500839008206370

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

A three-dimensional model for the octagonal phase based on a cut-projection from the eight-dimensional hypercubic lattice is presented here. The phason-phonon coupling which leads the octagonal phase into 45° twinned cubic ones is also studied. Conclusions of this realistic model do not modify the previously stated conclusions from the standard but incomplete two-dimensional treatment.

ISSN:0950-0839    

DOI:10.1080/09500839008206371

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor