Showing papers by "Mines ParisTech published in 1978"
TL;DR: In this article, the amount of twins vs applied strain was determined by quantitative microscopy at various temperatures in a Co-33Ni alloy, and the approach to saturation was described by two parameters which are temperature dependent through the temperature variation of stacking fault energy.
286 citations
TL;DR: In this paper, the experimental data currently available concerning the temperature dependence of the stacking fault energy (SFE, γ) observed in the study of the size variation of stacking fault nodes and ribbons in thin foils on a heating or a cooling stage in an electron microscope are reviewed.
255 citations
17 Jul 1978
TL;DR: It is shown that Milner's fully abstract model of Plotkin's PCP language only contains stable functions, and new model constructions from a notion of stable function are presented.
Abstract: Following Scott, the denotational semantics of programming languages are usually built from the notion of continuous functions. The need for restricted models has been emphasized by Plotkin and Milner, which showed thats continuous function models did not capture all operational properties of ALGOL-like sequential languages. We present new model constructions from a notion of stable function. This requires the introduction of two different orderings between stable functions which give very different cpo structures to the function spaces. We show that Milner's fully abstract model of Plotkin's PCP language only contains stable functions.
226 citations
TL;DR: In this paper, the authors measured the fatigue crack growth rate (FCGR) of Alloy 718 on CT type specimens at 298 and 823 K and found that a substantial increase in FCGR occurred at low stress intensity levels, as the temperature was increased from 298 to 823 k and as the frequency was decreased at 823k.
Abstract: The fatigue crack growth rate (FCGR) of Alloy 718 was measured on CT type specimens at 298 and 823 K. At 823 K, the influence of frequency was studied in the range between 5 – 10-3 Hz and 20 Hz, using a sinusoidal wave form signal. A substantial increase in FCGR occurred, particularly at low stress intensity levels, as the temperature was increased from 298 to 823 K and as the frequency was decreased at 823 K. At elevated temperature, the effect of cyclic stress wave form was equally investigated, using triangular and square wave form signals producing the same frequency of 5.10-2 Hz. The triangular load led to higher FCGR than the square wave form. In addition the hold time of 10 s both at the maximum and the minimum load associated with the square load had no significant effect on the FCGR. Electron microscopy was used to observe the substructures that developed ahead of fatigue cracks. These observations showed that in certain circumstances plastic deformation proceeded by the propagation of planar bands which were identified as twins. At room temperature, twinning was found to be abundant only in the threshold regime. At 823 K, twinning was observed in the domain of higher FCGR, particularly at low frequencies. Fractography was carried out to study the micromechanisms of crack propagation. At 823 K. intergranular cracking occurred as the frequency was decreased. The comparison between the substructures formed in low cycle fatigue and those associated with the plastic zones of propagating cracks is made. The importance of planar deformation and twinning on intergranular cracking and on the acceleration of FCGR when the loading rate is decreased at 823 K, is discussed.
119 citations
44 citations
36 citations
TL;DR: In this article, a slip line field model was developed for axisymmetric extrusion through conical dies, with a perfectly plastic material, obeying Tresca's yield criterion with its associated flow rule and with the Haar-Karman hypothesis.
14 citations
12 citations
TL;DR: In this article, a determination of θ = (V zz, H ) is made from 1 2 → 3 2 Mossbauer spectra with a quadrupole interaction which can be treated as a first order perturbation upon the magnetic interaction.
11 citations
TL;DR: In this paper, a dissociative mechanism, involving an equilibrium between substitutional iron atoms and interstitial iron atoms, is proposed, which is equally responsible for the abnormally high impurity diffusivities of iron, cobalt and nickel in γ-uranium, β-titanium and β-zirconium.
8 citations
TL;DR: In this article, a personal view is given on models and methods useful at various stages of the scientific process of understanding fluid phase equilibria, especially vapour-liquid equilibrium, and the needs for research with a view to its application are considered.
TL;DR: In this article, the magnitude of quadrupole splittings of iron atoms having two carbon nearest neighbors at a distance close to 2 A in Fe 3 C, Fe 5 C 2, Mn 5 SiC, and some M 3 M ′C perovskite carbides in the paramagnetic state are discussed.
TL;DR: In this article, two kinds of hardening precipitations are observed in the ferritic phase of a PH 15-7 Mo type stainless steel after aging heat treatment: NiAl and another intermetallic compound, already known as the R phase.
TL;DR: In this paper, an electronic device which facilitates quench from the liquid state for alloys whose liquid-solid region is large at high temperature is described, by means of the piston and anvil technique.
Abstract: Describes an electronic device which, by means of the piston and anvil technique, facilitates the quench from the liquid state for alloys whose liquid-solid region is large at high temperature. The block diagram of the device is given and the performance of the casting apparatus is evaluated.
TL;DR: Les parametres thermodynamiques et mecaniques de la mise en forme influent considerablement on the structure semi-cristalline des pieces obtenues.
Abstract: Les structures cristallines des polymeres synthetiques sont differentes de celles des materiaux naturels vegetaux ou animaux. Les parametres thermodynamiques et mecaniques de la mise en forme influent considerablement sur la structure semi-cristalline des pieces obtenues. Des exemples relatifs a l'injection, a la coulee de film, au soufflage de gaine, a la fabrication de fibres sont donnes. Les perspectives d'avenir concernent les relations mise en forme-structure-proprietes, et en particulier l'obtention de structures tres orientees a tres haut module.
TL;DR: In this paper, the authors present the result of an enquete internationale de l'UNESCO on les degâts materiels et les victimes des glissements, coulees et phenomenes associes, sur les etudes entreprises a leur sujet, notamment for levaluation des risques d'apparition de ces phenomenes and la localisation et le zonage des zones sensibles.
Abstract: On presente les resultats d’un enquete internationale de l’UNESCO sur les degâts materiels et les victimes des glissements, coulees et phenomenes associes, sur les etudes entreprises a leur sujet, notamment pour l’evaluation des risques d’apparition de ces phenomenes et la localisation et le zonage des zones sensibles.
TL;DR: In this article, the distribution of contraintes and deplacements in a massif semi-infini transversalement isotrope soumis a un cisaillement axisymetrique is determined.
Abstract: La distribution des contraintes et des deplacements a l’interieur d’un massif semi-infini transversalement isotrope soumis a un cisaillement axisymetrique a ete determinee. On calcule ensuite la repartition du cisaillement correspondant a un deplacement radial impose; on se ramene ainsi au probleme precedent. Des resultats numeriques sont presentes sous forme de courbes et montrent l’influence de l’anisotropie.