摘要:

When examining precipitation treated copper–silver alloys in transmission, several precipitation phenomena were observed. In the detailed study main emphasis was put on discontinuous precipitation associated with the growth of extrinsic stacking faults. In this process the growth of precipitates, which occurs on expansion consuming vacancies, was found to proceed in collaboration with the climb of Frank partial dislocations emitting vacancies.

ISSN:0031-8086    

DOI:10.1080/14786436808227742

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

Field ion images from ordered Ni4Mo with He and He–Ne mixtures are very stable and contain a variety of interesting crystallographic features. Translational antiphase boundaries are readily identified because of the layered structure of Ni4Mo and the prominence of the Mo atoms in the images. Although the Ni atoms do not image readily they are faintly visible on certain superlattice planes where they occur in layers. A dark zone pattern which is asymmetric with respect to the overall crystallographic pattern is shown to be related to the orientation of the ordered β structure with respect to the disordered face-centred cubic α structure.

ISSN:0031-8086    

DOI:10.1080/14786436808227743

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

Measurements of magnetization at temperatures down to 4°K and in applied fields up to 20 koe have been made on the cubic Laves phase compounds (Zr1-xTix)Zn2for values ofxranging from 0 to 0·26. Lattice parameters have also been measured. The magnetization and Curie temperature of the system increase with decreasing lattice parameter.

ISSN:0031-8086    

DOI:10.1080/14786436808227744

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

A theory of the f.c.c. to h.c.p. transformation in cobalt films suggests that thick films of f.c.c. (β) cobalt should be obtained if the metal is deposited onto an f.c.c. substrate whose lattice parameter is close to that of cobalt. Evidence in support of this prediction is provided by cobalt films grown at room temperature on alloys of nickel and palladium.

ISSN:0031-8086    

DOI:10.1080/14786436808227745

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The preferred orientation of cubic crystallites in a drawn or extruded material can be determined by well-known x-ray methods. The relationships between these observations, the single crystal elastic constants and the elastic constants of the polycrystalline material are discussed quantitatively.

ISSN:0031-8086    

DOI:10.1080/14786436808227746

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

Internal friction measurements have been made on electron-irradiated gold. The change in friction as a function of the total integrated electron flux was measured at 80°K and 280°K for an electron energy of 2 Mev. It was found that the results can be explained in terms of dislocation pinning if there are at least two dislocation systems present.

ISSN:0031-8086    

DOI:10.1080/14786436808227747

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The standard theory of cation diffusion-controlled oxidation in the scaling region (oxide film thicknesses > 10−4cm) is extended to take account of metal lattice vacancies generated at the oxide–metal interface. The general rate law for oxide layer growth has three limiting forms. Linear kinetics obtain if there is a large energy barrier for cation transfer from metal to oxide;X∝t, whereXis the film thickness andtis the oxidation time. If vacancy diffusion in the metal is slower than cation transport in the oxide, vacancy diffusion from the interface to sinks is rate-limiting andX3∝t2. Otherwise the oxide growth kinetics are parabolic,X2∝t, but the rate constant is reduced for metal substrates which can support a vacancy supersaturation.

ISSN:0031-8086    

DOI:10.1080/14786436808227748

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The creep behaviour of polycrystalline lithium fluoride under conditions of constant stress was investigated over the temperature range from 300°C to 550°C and found to be essentially similar to that observed in pure metals. The measured activation energy for steady-state creep was of the anticipated magnitude for diffusion of the fluorine ion, and the results suggest that the rate-controlling mechanism is some form of dislocation motion rather than the stress-directed diffusion of vacancies.

ISSN:0031-8086    

DOI:10.1080/14786436808227749

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The migration and trapping of inert gases in ionic solids is of practical interest in reactor materials and of scientific interest as a result of experiments designed to simulate practical situations on better-defined systems. Many of these experiments have been carried out with crystals of alkali halides and alkaline earth fluorides. The present paper extends the classical Born model of an ionic crystal to the calculation of the energies of migration and trapping of the inert gases Ar and Kr in K and Rb halides. The energies of solution and migration of interstitial Ar and Kr atoms are evaluated as well as their binding energies into ionic vacancies and vacancy pairs. The results are in good general agreement with the observations on gas release from these crystals after neutron irradiation. In particular the differing behaviour of Ar in KF and in the other K halides is accounted for in terms of a strong trapping of the Ar atoms into vacancy pairs which occurs in KF. It is predicted that the behaviour of Kr in RbF should be in even more striking contrast to its behaviour in the other Rb halides. Finally the paper touches on the implications for geologic dating of natural sylvine by determination of its40Ar content.

ISSN:0031-8086    

DOI:10.1080/14786436808227750

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The dislocation arrangement in the stress-applied condition of copper single crystals deformed in tension at 78°K was pinned by irradiating with a dose of 1018n/cm2fast neutrons at 4·2°K or 20°K. Transmission electron microscope studies of the primary glide plane showed that significant differences exist between the dislocation arrangements in the stress-applied and in the stress-removed state of the crystals, indicating considerable dislocation rearrangement during unloading. In particular, dislocation groups and pile-ups consisting of 10–20 dislocations of the same sign were observed in stage II in the stress-applied state.

ISSN:0031-8086    

DOI:10.1080/14786436808227751

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor