Showing papers in "Materials Science and Engineering in 1980"

TL;DR: In this article, a critical review of the results of experimental and theoretical investigations of the dependence of the flow stress τ on the dislocation density ϱ in crystals of different lattice types is presented.

TL;DR: In this article, the stress drop in the initial elastic region of the stress-strain curve and the Joule heating derived from the current-time profile and a reasonable heat transfer coefficient were calculated and found to be about 50-70% of the total stress drops associated with these temperature rises.

TL;DR: In this article, it was shown that the alloy elements nickel, molybdenum and chromium are accumulated in the metal phase underneath the oxide and that the enrichment of chromium seems to be dependent on the moly bdenum content of the alloy.

TL;DR: In this paper, a model for the superplastic deformation mechanism was presented and the fact that super-plasticity is a distinct rate-controlling mechanism in the high temperature deformation of fine-grained materials, with its own and unique dependence of strain rate on grain size, stress and temperature, was emphasized.

TL;DR: In this paper, an analysis of ribbon geometry data was used to establish simple empirical equations which relate ribbon width and thickness to process parameters such as the volumetric material flow rate, the substrate surface speed, the melt jet diameter and the impingement angle.

TL;DR: In this paper, the segregation of metallic additives M and metalloid impurities I to the free surface of iron was studied by Auger electron spectroscopy in dilute binary and ternary iron-based alloys.

TL;DR: In this paper, it is suggested that the discussed instability is due to secondary glide on systems intersecting the primary slip plane which, through moving primary edge dislocations normal to their slip planes, permits their mutual annihilation.

TL;DR: In this paper, a review of the use of threshold stresses and back stresses to characterize fluid flow, diffusional creep, superplastic deformation, power law creep in relatively pure metals and dislocation creep in dispersion-strengthened materials is examined.

TL;DR: In this paper, splat quenching of the alloys resulted in a high degree of microstructural refinement that was preserved through the hot consolidation and heat treatment steps, which was concluded that with proper alloy design the splat-quenching technique can be used successfully to develop Al-Li-based alloys with overall improved properties.

TL;DR: The fracture behavior of recrystallized Al-2.8wt.% Li-0.3wt. Mn was investigated as a function of artificial aging conditions in this paper, where a precipitate free zone (PFZ) developed to accomodate the accelerated growth in the grain boundary regions.

TL;DR: In this article, the state of the iron surface at elevated temperatures in gas atmospheres and in a vacuum and on the kinetics and mechanisms of some metallurgically important gas-metal reactions were reviewed.

TL;DR: In this paper, the fatigue fracture surfaces of AISI 316 (Z6 CND 17-12) stainless steel in the range of low crack growth rates in air at ambient temperature revealed coloured zones ranging from grey to yellow parallel to the crack front.

TL;DR: An improved model to predict the strength of a composite laminate containing a slit notch through crack is developed, assuming the material characteristic dimension to be an exponential function of crack size, and a superposition method is developed which allows data for all composite material systems described by the developed model to be superimposed as discussed by the authors.

TL;DR: In this article, anodic polarization of sulphur-doped nickel was observed to cause selective dissolution of nickel and surface segregation of sulfide, which caused a complete inhibition of passive layer formation when the sulphur content is above a critical concentration.

TL;DR: In this article, the optical constants of film-free surfaces of the alloys were determined by ellipsometry in dehydrated methanol immediately after stripping the surface films in a bromine-methanol solution.

TL;DR: In this paper, it was shown that simple relations exist between the elastic moduli of polycrystalline metals: G/E = a, G/B = b, and E/B= c. The values of the proportionality factors a, b and c for each individual type of crystal structure are different.

TL;DR: In this article, the surface concentration and possible exchange reactions (dissolution, surface or grain boundary segregation) between surface, interface and solid solution can be accurately measured using low energy electron diffraction, Auger electron spectroscopy and work function measurements.

TL;DR: In this article, the creep crack growth behaviors of alloy 718, Inconel X-750, Udimet 700 and cold-worked type 304 were determined in vacuum at elevated temperatures and the results were compared with those previously obtained in air.

TL;DR: In this article, a batch of 10%Mg alloy was stirred in a batch-type apparatus at a low cooling rate (1.5 K min −1 ) for a range of stirring periods and shear rates and was quenched in the semisolid state.

TL;DR: In this article, the effect of the copper content and degree of recrystallization (DR) on fatigue crack propagation behavior was investigated in dry air, in distilled water and in a 3.5% NaCl solution.

TL;DR: In this paper, a new ellipsometer is presented which is simpler and easier to use than conventional instruments, which is used to compare a test surface with a known reference surface.

TL;DR: A great deal of progress has been made recently in the understanding of impurity-induced intergranular embrittlement of alloy steels, and a technique has been developed for calculating the transition temperature as a function of the hardness and grain size of the steel and the Auger peak height ratio due to metalloid elements as mentioned in this paper.

TL;DR: In this paper, a study of electron beam surface melting was conducted and the nature of rapidly quenched microstructure and melt zone geometry parameters (the depth, the width and the length) were related to the beam velocity and the power density and are then compared with predictions of heat flow models.

TL;DR: In this paper, a superplastic aluminum alloy based on the hitherto unexploited AlCaZn eutectic system is described, and the super-plastic forming behavior of a 5.5wt.%Zn alloy and the mechanical properties at room temperature after forming are determined.

TL;DR: In this article, the role of the strength of the alloy matrix in the creep resistance of nickel-based super-alloys is considered and a generalized expression for creep rates which separates the matrix contributions from the particle contributions to resist stress and creep strength is derived.

TL;DR: The effect of chromium on the formation and stability of the passive film formed on ferritic stainless steels (5.9 - 29.9% Cr) in 3% NaCl was studied by electron spectroscopy for chemical analysis.

TL;DR: In this paper, the cyclic stress-strain curves for low carbon steel in the range from the strain fatigue limit ϵ ap C up to the fatigue ductility, obtained both for strain controlled cycling and for stress-controlled cycling with various mean strains ϵ m and mean stress σ m.

TL;DR: In this article, the surface chemistry of steel sheet and black plate for cold forming is described and some examples of the improvements that can be achieved with a better knowledge of the surfaces chemistry of tinplate and galvanized steel sheet.

TL;DR: In this paper, a comparison of the behaviour of oxygen-free copper with that of samples containing oxygen was made, showing that prestraining invariably resulted in a reduction in creep ductility whereas the creep rate and rupture life could be increased or decreased depending on the extent to which the incidence of grain boundary cavities was affected.