摘要:

The grain-boundary diffusion of Cr in Nb bicrystals with 8°[110]/[112] symmetrical tilt boundaries was measured in the temperature range 947–1150°C, using electron probe microanalysis. The dependence of the grain-boundary diffusion coefficient D' on temperature T is given bywith an activation energy of 42961 cal mol−1

ISSN:0950-0839    

DOI:10.1080/09500839208219046

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A rheological constitutive equation for associating comb-shaped or H-shaped polymer solutions is derived, which shows a unique power-law zone characterized by two time parameters and one power-law exponent in the terminal relaxation region. The constitutive equation is of fractional integral or fractional differential type and contains two additional parameters. A comparison with experimental data demonstrates very good agreement with the theoretical predictions. The material functions in the frequency domain represent a generalization of the well known Cole-Cole behaviour.

ISSN:0950-0839    

DOI:10.1080/09500839208219047

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The question of the effect of an imposed strain on the topology of a soap froth is addressed through numerical simulations. Both the standard model of a ‘dry’ twodimensional foam and the case of small liquid fraction are explored. The froths are subjected to both extensional deformation and simple shear. The counter-intuitive result that application of strain can induce ordering in a disordered froth is obtained, quantified and discussed. A qualitative dynamical explanation is proposed.

ISSN:0950-0839    

DOI:10.1080/09500839208219048

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The tracer diffusivity of Co in amorphous NixZr1-x has been measured as a function of pressure for 0·42≤x≤0·62. The primary conclusions that can be drawn from the results of these measurements is that the activation volume △V of diffusion in amorphous NixZr1-xalloys is about (8-20) × 10−30m3, and it is dependent upon alloy composition. The results are discussed in terms of a previously proposed interstitial-like diffusion mechanisms for Co in amorphous Ni-Zr.

ISSN:0950-0839    

DOI:10.1080/09500839208219049

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The Rodrigues method, formulated first as a geometrical construction and later in vector notation, provides a simple and direct means of visualizing and calculating the total rotation resulting from two sequential rotations. In this paper the case of the five degrees of freedom for a grain boundary are considered. The Rodrigues method is applicable since the total misorientation is a tilt followed by a twist rotation, and calculations are much simplified since vectors rather than matrices are involved.

ISSN:0950-0839    

DOI:10.1080/09500839208219050

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Stress-strain hysteresis in alumina with microcracks has been investigated by a loading–unloading test in the microstrain range around 10−4While there remains a permanent strain after the initial loading, steady-state cyclic loading results in a single closed hysteresis loop with a symmetrical shape. Such a stabilized hysteresis loop is responsible for internal friction and can be attributed to the microplasticity associated with a forerunning phenomenon of fracture.

ISSN:0950-0839    

DOI:10.1080/09500839208219051

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The anisotropies of electrical resistivity and thermal expansion of single-crystal Ti5Si3have been measured in the temperature ranges 4·2–300K and 300–1273 K respectively. The anisotropy of the thermal component of the resistivity, defined as ρ(273 K)—p(4·2 K), was found to be 1·65 and the anisotropy of the thermal expansion 2·7 at 1273 K. The anisotropies are discussed on the basis of the directionality of the bonding forces.

ISSN:0950-0839    

DOI:10.1080/09500839208219052

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Crack propagation behaviour in sintered alumina has been observed by in situ straining experiments in a transmission electron microscope at 800°C. Dislocations were generated at the crack tips, and the strain contour line around the crack tips was found to oscillate periodically during crack propagation. Crack deflection through grain boundaries occurred after a fan-shaped strain appeared when the crack intersected the grain boundary.

ISSN:0950-0839    

DOI:10.1080/09500839208219053

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor