Showing papers in "Acta Metallurgica in 1975"

TL;DR: In this paper, the authors analyzed the kinetic problem of intergranular fracture at elevated temperatures by the nucleation and growth of voids in the grain boundary and calculated the time-to-fracture.

TL;DR: In this article, a structural model for the solid-liquid interface has been developed by applying the construction rules for the liquid to the boundary condition of a crystal plane, which can account qualitatively for the ease of step nucleation during crystal growth.

TL;DR: In this article, the contribution of power-law creep to the final stage densification of a powder compact is investigated, and it is modelled by considering the voids as spherical holes surrounded by a thick cylindrical shell of solid material which flow by power law creep.

TL;DR: In this paper, the authors examined the stress-strain behavior of quenched and tempered AISI 4310 and 4330 steels in tension and compression under superimposed hydrostatic pressures up to 160 ksi (1104 MN/m 2 ).

TL;DR: In this paper, a mean-field free energy is formulated in k-space and applied to order-disorder reactions in substitutional solid solutions whose average lattice is i'.c.c or b.c.

TL;DR: In this paper, a finite-element computational method was used to model the creep of polycrystalline solid by attributing a Newtonian-viscosity to the grain boundaries and a power-law viscosity to the interior.

TL;DR: In this paper, the early stages of spinodal decomposition in age hardening Cu-Ti alloys have been studied by electron microscopy, and a sequence of microstructures was used to show that continuous phase separation was the mechanism of decomposition.

TL;DR: In this paper, the mean stress and strain in the matrix of such materials, and for the workhardening caused by the mean stresses are taken into account, and the theoretical hardening rate is less than the observed value, but the theory is demonstrated to have considerable empirical value in predicting the initial hardening rates in dispersionhardened metals, over-aged precipitation-hardened alloys and fibre-reinforced metal composites.

TL;DR: In this paper, the consensus values of Hall-Petch constants for a least-squares fit to data of this and four previous investigations were σ0 = 21.8 MN/m2 and k = 0.158 NM/m 3 2.

TL;DR: In this paper, the microstructure of the strongly deformed compound wires as functions of the degree of deformation and the fibre diameter were discussed. But the authors did not consider the effect of the diameter of the fibres.

TL;DR: A sigmoidal relationship between strain rate and stress was observed in a superplastic Zn-22% Al eutectoid alloy with grain sizes in the range of 2.1-7.5 μm.

TL;DR: In this paper, a comprehensive theory of the defect interactions and kinetics leading to swelling and creep is developed, with particular attention given to determining the densities of point defect sinks, both dislocations and voids, and their dependence on the irradiation temperature.

TL;DR: In this paper, the probability that the rotation across a grain boundary in a random polycrystalline aggregate will lie within specified deviations of rotations leading to a CSL or a CAD (coincident axial direction) was investigated.

TL;DR: In this paper, the discrepancy between two recent phase diagram determinations of the Fe-Al system is resolved experimentally, and the form of the combined coherent and incoherent phase diagram for these alloys is critically discussed.

TL;DR: In this article, Tungsten spheres of uniform size were coated with copper and then heated above the melting point of copper for four minutes, and by direct comparison of the presintered and the liquid phase sintered condition the movements of individual particles could be measured as a function of the amount of liquid, wetting angle and packing density.

TL;DR: In this article, Tungsten spheres of uniform size were coated with copper and then heated above the melting point of copper for four minutes, and by direct comparison of the presintered and the liquid phase sintered condition the movements of individual particles could be measured as a function of the amount of liquid, wetting angle and packing density.

TL;DR: A sigmoidal relationship was observed between strain rate and stress in the Zn-22% Al eutectoid alloy, dividing the behavior into three distinct regions as mentioned in this paper, and the results support the suggestion that the behavior in this region arises from an intragranular creep process.

TL;DR: In this paper, the relationship between the particle size and the size of the cavity nucleated at the particle is discussed as is the frequency of cavities as a function of particle dimensions and interparticle spacing.

TL;DR: In this article, it is shown how microstructural ideas involving dislocation micro-mechanisms do, when properly coupled to the classical continuum theories, prescribe not one but several forms of kinematic hardening and these forms are suggestive of strain hardening mechanisms on the micro as well as on the macro scale.

TL;DR: In this paper, the perturbation theory was applied to the problem of the fracture of the liquid layer formed during the deformation of a metallic glass, and a relation between the fracture stress and the fine features of fracture morphology was predicted, in agreement with experimental results.

TL;DR: In this paper, the decomposition tie line of a quenched and aged alloys along the composition line was studied by electron diffraction and microscopy, and it was suggested that for the symmetrical alloy, the structure of the Cu3Al-rich particles varies with decomposition temperature.

TL;DR: In this article, a two-stage model is proposed for whisker growth, where expansion of a dislocation loop by climb under emission of vacancies which diffuse far away from the whisker root region is followed by glide of the loop through the network of other dislocations towards the surface.

TL;DR: In this article, the exact equilibrium shapes of nuclei at a grain boundary in the presence of a facet at one orientation of the nucleus-matrix boundary determined in the two-dimensional case were investigated under the same conditions.

TL;DR: In this paper, a high-resolution election microscope study was conducted to follow the precipitation sequence. But the results were limited to a single atom layer and were not accompanied by any distinct microstructural change, rather, a continuous structure progression was observed from G.P. to θ.

TL;DR: In this paper, the effect of parent phase ordering in depressing the T 0 temperature has been satisfactorily explained using a quasichemical approach and a consequent difference in bonding enthalpies.

TL;DR: In this article, the results of recent X-ray and neutron studies of axial ratio anomalies associated with carbon atom distributions in the tetragonal martensite lattice are analyzed.

TL;DR: The strain controlled low cycle fatigue properties and cyclic stress-strain response of a 4140 steel were investigated as functions of tempering temperature in this paper, and it was suggested that the endurance limit is essentially equal to the cyclic yield stress.

TL;DR: In this article, a slip band formation in a β-titanium Ti-9.8 wt. % Mn alloy was found to start at grain boundaries and proceed inward.

TL;DR: In this paper, a restricted-slip mechanism was proposed to account for the observed plane of fracture in a pure Al-Cu alloys, and the results of environmental and mean stress experiments show conclusively that a true cleavage mechanism cannot operate.

TL;DR: In this paper, the growth of necks in relatively smooth tension creep samples with non-uniform cross-sections is studied using numerical techniques, and the shape of the sample and the average creep rate are calculated as a function of average strain or time for various initial shapes and creep stress exponents for both the constant load and constant stress conditions.