Showing papers in "Acta Metallurgica in 1980"

TL;DR: In this article, the growth of cavities along grain interfaces was analyzed by the combined processes of grain boundary diffusion and plastic dislocation creep in the adjoining grains, and it was shown that the coupling between the processes can be expressed in terms of a parameter L, which has the dimensions of length and which is a function of material properties, temperature and applied stress.

TL;DR: In this paper, the latent hardening ratios (LHRs) were measured for different values of primary shear strain in Stage 1, and for various latent systems, including copper and aluminium single crystals.

TL;DR: In this article, microstructural evidence, together with a thermodynamic analysis, of the bainite reaction in steels are presented in support of a growth mechanism involving the propagation of displacive sub-units.

TL;DR: In this article, the authors used the best available diffusion data for metals and ceramics to investigate the relationship between the melting point diffusivity and activation energy of a given crystal structure and bond type.

TL;DR: In this paper, a trap binding energy of 14.3 ∓ 1.1 kcal (59.9 ± 4.6 kJ mol−1H) was determined.

TL;DR: In this article, a phenomenological model free energy function is presented which accounts for the shape memory effect (SME) in alloys, based on Landau's theory, and the mechanical and thermodynamical consequences of the model (such as stress-strain curves, elastic constants and the latent heat of the phase transition) are discussed.

TL;DR: The change in viscosity of a Pd 82 Si 18 glass during isothermal annealing has been measured in the temperature range of 424-537 K for times up to 325 h as mentioned in this paper.

TL;DR: In this article, a new theory was presented to describe the segregation-induced changes in grain boundary cohesion, which enables the changes to be calculated readily from tabulated thermodynamic data of sublimitation enthalpies and atom sizes.

TL;DR: In this paper, the authors extended the classical theory of the coarsening of precipitate particles by competitive growth to include the effect of encounters between growing particles using the method outlined by Lifshitz and Slyosov [J. phys. solids19, 35 (1961)].

TL;DR: In this paper, the incremental yield stress due to coherency stress in a spinodal modulated structure in f.c. alloys has been considered using the dislocation force balance equation.

TL;DR: In this article, a theory has been developed that relates many particularities of hydrogen embrittlement to the behavior of the trap population of the material during its exposure to hydrogen, and it is shown that reversible traps may act as innocuous sinks or as detrimental hydrogen sources, depending on test conditions.

TL;DR: In this paper, the coefficient de diffusion de silicium dans la silice amorphe entre 1110 and 1410°C was measured, in the form of: D(cm 2 s −1 ) = 328 exp (− 579KJ RT ) = 320 exp (− 6eV kT ).

TL;DR: In this article, a Griffith-type fracture criterion was developed for any deformable solid, regardless of whether the brittle mode is transgranular cleavage or intergranular fracture.

TL;DR: In this article, the activation energy for steady-state creep (Qss) was found to be equal to about 87 kj mole−1 which corresponds quite closely to the activation energies for dislocation pipe diffusion as measured by Volin, Lie and Balluffi using a void shrinkage analysis.

TL;DR: In this paper, the saturation flow stresses and ladder spacings were a function of fatigue temperature only and were not dependent on specimen history, and the observed flow stresses were 25, 48 and 73 MNm− 2, and observed ladder spacing were 1.3, 0.7 and 0.45 μm at 295, 77.4 and 4.2 K respectively.

TL;DR: In this article, the equilibria of small solid solution crystals with isotropic surfaces in contact with vapor or fluid solutions are considered when the surface stress differs numerically from the surface free energy.

TL;DR: In this paper, a first attempt is made to incorporate the various disparate facts concerning their growth into a coherent growth model in particular, the usual minimum undercooling criterion is abandoned in favour of one based on the morphological instability and branching of the phases Despite numerous approximations, the correct order of magnitude of spacing and under cooling is predicted, as is the effect of the imposed temperature gradient.

TL;DR: In this paper, the pressure distribution over the area of contact between spheres undergoing linear deformation is calculated for non-linear deformation problems, such as Meyer hardness, creeping indentation and hot pressing of aggregates.

TL;DR: The equilibrium shape of gold crystallites on a graphite cleavage surface has been studied in this paper, where the crystallites (a few μm in diameter) were obtained by annealing a continuous gold film under U.H.V. for about 70 h at 1273 K.

TL;DR: In this paper, single crystals and polycrystals of pure copper were fatigued in tension-compression at constant low amplitudes of plastic strain and low cycling frequencies at room temperature in air.

TL;DR: In this paper, the embrittlement of Al-6wt.%Zn-3.%Mg alloy exposed to water vapour at elevated temperatures has been investigated.

TL;DR: The geometric properties of polygranular microstructures of the Johnson-Mehl cellular types have been studied through computer simulation as mentioned in this paper, and their geometric features have been characterized through a combination of analytic and computer simulation studies.

TL;DR: Theoretical models of dynamic strain ageing in general and the onset of serrated yielding in particular are based on the interaction between moving dislocations and diffusing solute atoms as discussed by the authors.

TL;DR: In this article, a statistical model of high temperature failure in ceramics, by the viscous or diffusive growth of cavities, has been developed, and general expressions for the creep strain associated with cavitation and for the failure time have been derived, and shown to be in good agreement with available data.

TL;DR: In this paper, a summary of the morphologies and TEM diffraction effects of the several metastable phases observed when a supersaturated Cu-2w/0 Be alloy decomposes at temperatures ranging from 500°C (773 K) to room temperature is given.

TL;DR: In this article, the authors considered the heterogeneous nucleation of martensite at a dislocation using an elasticity model, where the dislocation is allowed to have an arbitrary Burgers vector representing, in an approximate manner, the stress field of a pile-up.

TL;DR: In this paper, the relation between grain boundary hardening and segregation in alpha iron-tin alloy was investigated and it was found that the grain boundary hardness depends on the grain boundaries misorientation and the amount of tin segregation to grain boundaries.

TL;DR: In this article, the authors examined the nature and significance of carbide precipitation accompanying the lower bainite transformation in steels and found that such precipitation is strongly inconsistent with the concept of 'interphase precipitation' at the α/γ transformation interface.

TL;DR: In this article, a cubic-type crystal model is used to describe the distribution of nearest neighboring atoms about a given atom in an interface of arbitrary orientation between two cubic type crystals.

TL;DR: In this article, the elastic field and stress concentration around a second phase particle have been discussed in the unrelaxed and relaxed states, and it has been pointed out that a flat shaped particle behaves, as if it were a shear crack, in the relaxed state.