At the 2001 Autumn Meeting of SF2M (the French Metallurgy and Materials Society), a symposium has been organized in the memory of Jean Morlet, late President of Revue de Métallurgie. Different contributions to this symposium, representative of the type of approach favoured by Jean Morlet, are published in the present issue of Science et Génie des Matériaux.

This tribute presents different ways in which Jean Morlet stimulated the cooperation between basic and industrial research : identification and optimum use of the fundamental competences able to contribute to the enhancement of the industrial skills, actor and coordinator in the area of public research, supporter of an interdisciplinary approach, active member of the scientific community.

Modelling is a powerful tool for preparing and carrying industrial developments through. Jean Morlet used modelling widely and contributed to the opening out of a strong French school. Several types of development will be presented and illustrated with concrete achievements carried out during the course of Jean Morlet's career.

The CEQCSI software (Chemical EQuilibrium Calculation for the Steel Industry) was developed at IRSID under the guidance of Jean Morlet. This paper discusses the place of CEQCSI in the fast expanding field of Computational Thermodynamics packages, analyzes the major impact experimentation at Imphy had on its evolution, presents a few examples of industrial applications in ladle metallurgy and inclusions control, and finally evokes trends in the association of thermodynamic codes with CFD (computational fluid dynamics) codes and kinetic models.

A growing interest for magnesium alloys has been observed recently in the field of weight reduction for structural applications. The purpose of this study is the development of novel alloys by using thermodynamic equilibrium calculations in order to determine the most promising compositions and their process parameters (solidification, heat treatments) within the Mg-Y-Sc-Mn system. Samples have been prepared and analyzed and the results agree well with the predictions.

A thermodynamic approach has been used to progress in the understanding of the chemical processes taking place in the casting furnaces. The ceramic mould materials used for the casting of superalloys vaporize at high temperature under vacuum and the vapors condense then in the colder zones of the furnace. In addition, the graphite of the furnace resistor perturbs the vaporization regime of the moulds and is at the origin of other vaporization and condensation processes. The deposition regime of impurities leading to inclusions formation during the casting of the metal is modified. The thermodynamic analysis is confirmed by observations made on the superalloy casting furnaces. The deposits observed and characterized correspond to those predicted by the thermodynamic analysis, but the mass losses of the moulds producing these deposits are 60 times smaller than predicted.

The hot tearing of aluminium-copper alloys is a serious defect for the foundrymen. The grain refinement of these alloys allows to decrease their hot tearing susceptibility. The aim of this work is to better understand the hot tearing mechanism and the grain refinement action. So, hot tearing tests and tensile tests in the mushy state have been performed. Moreover, a hot tearing model, based on the nucleation and growth of a cavity in a liquid film and taking into account the mushy zone rheology, has been developed.

After a short historical review, this paper recalls the successive steps of the life prediction of single crystal turbine blades, paying attention to a proper modelling of the material, to the mechanical aspects in the blades, and to the boundary conditions. The code built around the FE solver ZéBuLoN is now able to predict crack initiation by post-processing of the 3D elasto-viscoplastic computations.

In the model presented, phase transformations in steels are described using thermodynamic and kinetic laws at the scale of an austenite grain. A single geometric treatment leads to the final transformed fraction. The effect of composition, temperature path and austenite grain size is taken into account. The predictions of the model are compared with experimental results concerning different steel grades. The results obtained for ferrite, bainite and final ferrite grain size are encouraging.

The concept of forced alloys is explained and application examples are described. Systematic experiments with natural test pieces and by computer simulations show that, under the working conditions studied (irradiation, crushing, cyclic loading), the alloy may reach a stationnary configuration. Among the parameters controlling this process, the working intensity is of particular importance. The introduced concepts are applied to the study of the wear behaviour of fast train wheels (TGV). Wear rates and out-of-roundness are found to be proportional to this intensity.

The orientation distribution of high order twins is computed from the texture determined from neutron and EBSD measurements on a 70 % cold rolled Fe-36%Ni sample. As experimentally observed, during annealing, the simulated twinned texture tends to become isotropic. Moreover, as experimentally observed and numerically verified, it appears that three twin generations develop after the complete recrystallization. Finally, if it is obvious that both the nucleation (and growth) of all possible orientations of the cold rolling texture and the multiple twinning can contribute to explain the isotropic part formation of the recrystallization texture, and it seems that this second mechanism plays an important role.

The superelastic behaviour of shape memory alloys is now successfully modelled. On the other hand, the anisothermal creep is badly described, both by phenomenological models and by micro-macro formulations. In this paper we introduce a new approach, based on the concept of group of variants to more precisely describe the microstructure obtained during stress assisted two way memory. A new variants selection criterion is proposed.

A quantitative method is described for the measurememnt of displacements and strains by high-resolution electron microscopy. The image is considered to be composed of periodic sets characterized by Fourier analysis. The local amplitude and geometric phase of lattice fringes can be determined in this way. The analysis of the phase distribution leads to the determination of the local lattice configuration. The method is illustrated by different examples and its application conditions are discussed.

Artefacts of World War I were studied to better understand iron corrosion phenomena in clay soils. The identification of their two corrosion layers by Raman spectroscopy highlighted iron oxides and oxy-hydroxides. Electrochemical experiments confirmed the porosity of the external layer, and the protective role of the internal products. The influence of the burial environment on the corrosion rate was also proved.