摘要:

In order to calculate the rate of escape of vacancies at the surfaces of a thin foil specimen prepared from a quenched sample of an aluminium-5 wt. % magnesium alloy, Eikum and Thomas, in a recent paper, used a mobility energy deduced from a plot of rate of loop growth versus reciprocal temperature. It is shown that diffusion parameters derived from such Arrhenius plots are not usually meaningful unless extreme precautions are taken. It is reconfirmed that the observed growth of prismatic loops in the aluminium alloy is only possible if the foil surfaces are sealed by an oxide film. Other evidence for the oxide film effect is reviewed and discussed.

ISSN:0031-8086    

DOI:10.1080/14786436808226156

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

Large plastic deformations have been produced in a glass-ceramic derived from the SiO2–Li2O–ZnO system, and the nature of the deformed phases has been studied using the combined techniques of x-ray diffraction, replica and thin foil electron microscopy and electron diffraction. Typical deformation structures have not been observed in the crystalline phases which are α-quartz, lithium disilicate and lithium zinc silicate. Consequently, it is concluded that any crystal deformation required in order to accommodate shear in the glassy phase, must be accompanied by recrystallization. The lithium disilicate grains contain plates, ∼ 100 Å thick, of ‘foreign’ material which is attributed to lithium zinc silicate. The variation of plastic deformation with temperature is discussed in terms of the present observations.

ISSN:0031-8086    

DOI:10.1080/14786436808226157

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

This paper reports the effect of 2 Mev electron irradiation below 31°K on the yield stress of copper single crystals measured at 25°K. Irradiation produces a large increase in the yield stress, which is interpreted as dispersed barrier hardening due to interstitials.

ISSN:0031-8086    

DOI:10.1080/14786436808226158

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The Compton line shapeJ(q) neglecting binding has been evaluated for the elements Li to Ge from the Hartree–Fock wave functions of Clementi (1965).

ISSN:0031-8086    

DOI:10.1080/14786436808226159

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

In a previous paper (Brandon and Perry 1967) the computer model of a field-evaporated crystal surface (Moore 1962) was extended to include the case of a dislocated b.c.c. crystal. The present paper describes a further extension to the case of a single dislocation loop or dipole in either f.c.c. or b.c.c. crystals.

ISSN:0031-8086    

DOI:10.1080/14786436808226160

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The difference between the maximum and minimum energies of a uniaxial single domain particle under an applied field is calculated for a range of orientations of easy axis to field from 0°–90° of arc. From this table the critical fields for discontinuous magnetization rotation over a range of temperatures can be deduced.

ISSN:0031-8086    

DOI:10.1080/14786436808226161

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The attenuation and rotation of the plane of polarization of ultrasonic shear waves propagating parallel to a strong magnetic field have been measured in copper single crystals. For sound propagation along [100] and for the case whenql≃1 the results agreed quite well with the predictions for the free electron model. For propagation along [110] and [111] only the magnitude of the zero field attenuation agreed with the simple theory. Measurements for the [111] orientation were complicated through strong internal conical refractions of the sound waves.

ISSN:0031-8086    

DOI:10.1080/14786436808226162

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

This paper considers the stability of a planar solid/liquid interface during the melting of a binary alloy. The method used is similar to that originally applied by Mullins and Sekerka to the case of solidification of such an alloy; a similar approximation of using steady-state diffusion equations for small perturbations is applied. The effects of diffusion of the solute in the solid, which were ignored by Mullins and Sekerka, but which are expected to be of greater importance in melting, are included in this analysis. It is shown that the onset of constitutional superheating is a necessary, but not a sufficient condition for the onset of instability in the interface; indeed, the extent of instability is much more restricted than that of constitutional superheating. The criteria for instability derived are also discussed in relation to the experimental work of Woodruff and Forty on the melting and constitutional superheating of sodium–potassium alloys.

ISSN:0031-8086    

DOI:10.1080/14786436808226163

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The magnetic susceptibility and solvent Knight shift changes caused by the rare earth series of elements dissolved in liquid aluminium have been measured for solute concentrations less than 2 at. %. Except for the cases of Eu and Yb, the impurity susceptibility conforms quite closely to the theoretical predictions obtained from the theory of Van Vleck for trivalent ions. Eu and Yb are best approximated by divalent ion core states.

ISSN:0031-8086    

DOI:10.1080/14786436808226164

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The influence of long-range ordering on the shear modulusGof Au3Cu and Cu3-Au has been measured. The results, while mostly agreeing well with the accepted ordering theory, show a surprising decrease ofGin the final stage of ordering. We suggest that this final decrease is caused by the disappearance of anti-phase boundaries.

ISSN:0031-8086    

DOI:10.1080/14786436808226165

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor