E.I. Galindo-Nava

A thermostatistical theory for solid solution effects in the hot deformation of alloys: an application to low-alloy steels

The hot deformation of low-alloy steels is described by a thermostatistical theory of plastic deformation. This is based on defining a statistical entropy term that accounts for the energy dissipation due to possible dislocation displacements. In this case, dilute substitutional and interstitial atom effects alter such paths. The dislocation population is described by a single parameter equation, with the parameter being the average dislocation density. Solute effects incorporate additional dislocation generation sources. They alter the energy barriers corresponding to the activation energies for dislocation recovery, grain nucleation and growth. The model is employed to describe work hardening and dynamic recrystallization softening in fifteen steels for a wide range of compositions, temperatures and strain rates. Maps for dynamic recrystallization occurrence are defined in terms of processing conditions and composition.

Engineering grain boundary sliding and cavitation effects in superplastic alloys employing thermodynamics

Abstract Plastic deformation by grain boundary sliding in superplastic alloys is described by a novel thermostatistical approach. The Gibbs free energy for cavity formation at moving grain boundaries is obtained. It equals the competition between the stored energy at the boundaries and the energy dissipated by grain boundary sliding. The latter is approximated by an entropy term induced by moving dislocations to facilitate boundary displacement. Strength loss evolution is estimated from the cavity evolution rate. The theory describes superplastic behaviour of Zn22Al, Zn21Al2Cu and Mg3Al1Zn for various temperatures, strain rates, grain sizes, and specimen geometries. Transition maps are defined for finding the optimal conditions for achieving superplastic behaviour in terms of composition, temperature, geometry and strain rate.

Research data supporting Gamma Prime Precipitate Evolution During Aging of a Model Nickel Based Superalloy

Excel spreadsheets containing the particle size distributions (PSDs), compositions of each phase, lattice parameters and proximity histograms of composition across the precipitate - matrix interfaces.

Discovery of New Materials and Heat Treatments: Accelerated Metallurgy and the Case of Ferrous and Magnesium Alloys

Traditionally, the discovery of new materials has been the result of a trial and error process. This has resulted in an extremely time-consuming and expensive process. Models for guiding the discovery of new materials have been developed within the European Accelerated Metallurgy project. The application of statistical techniques to large materials datasets has lead to the discovery of unexpected regularities among their properties. This work focuses on mechanical properties. In particular, the interplay between yield strength, ultimate tensile strength and elongation. A methodology based on principal component analysis, and Kocks-Mecking modelling has led to a tool for finding optimal compositional and heat treatment scenarios. The model is first presented for wide ranges of alloys, and the application to the discovery of new magnesium and ferrous alloys is outlined.