Papers by Author: E. Evangelista

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Authors: Marcello Cabibbo, E. Evangelista, S. Spigarelli
Authors: Marcello Cabibbo, E. Evangelista, C. Scalabroni, Ennio Bonetti
Abstract: The microstructural evolution with strain was investigated either in a Zr-modified 6082 Al-Mg-Si alloy and in the same alloy added with 0.117wt.% Sc, subjected to severe plastic deformations. Materials were deformed by equal-channel angular pressing using route BC, up to a true strain of ∼12. A strain of ~4 produced a sub-micrometer scale microstructure with very fine cells (nanometer scale) in the grain interior. The role of fine dispersoids (Al3(Sc1-x,Zrx)) was investigated by transmission electron microscopy techniques and discussed. Dispersoids were responsible for a more complex dislocation substructure with strain. Compared to the commercial parent alloy, block wall formation and propagation were favored by the presence of Sc-Zr containing dispersoids, while cell boundary evolution was less affected, compared to the commercial parent alloy. Mean misorientation across block walls increased with strain much more in the Sc-Zr containing alloy, reaching a plateau, starting from a true strain of ∼8. Misorientation across cell boundaries continuously increased to ∼8° and ∼5° for the Sc-Zr and Zr containing alloy, respectively.
Authors: E. Evangelista, Marcello Cabibbo, S. Spigarelli, C. Scalabroni, Luigi Balloni, R. Villa, G.L. Chiarmetta
Abstract: The tensile properties and the microstructure of an Al-7%Si-0.6%Mg-0.5%Cu rheo-cast component were investigated. The material underwent a T5 treatment, consisting in ageing at 160, 175 and 190°C for durations ranging from 0.5 to 48h. Tensile testing indicated that the T5 treatment resulted in a relatively good level of strength and in a comparatively low ductility. In order to improve ductility, maintaining as low as possible the cost of the final component, a single solution treatment at 500°C for 4h was subsequently applied. The tensile strength and ductility of the solution treated and aged material were higher than in the T5 condition. These differences were attributed to the microstructural evolution occurring during exposure at 500°C, in particular to the spheroidization of eutectic-Si and to a more homogeneous distribution of the precipitates.
Authors: E. Evangelista, M. Vukčević, F. Bardi, S. Spigarelli, Kemal Delijić
Authors: Stefano Amadori, Luca Pasquini, Ennio Bonetti, Marcello Cabibbo, C. Scalabroni, E. Evangelista
Abstract: Mechanical spectroscopy was employed to investigate the microstructure evolution of a Zr-modified 6082 Al-Mg-Si alloy and the same alloy with Sc addition after ageing and following severe plastic deformation through equal channel angular pressing. Measurements of the internal friction and dynamic young modulus have been performed in isothermal and isochronal runs in the frequency range 0.1 - 104 Hz. The anelasticity spectra reveal in the temperature range 470-870 K both structural and anelastic relaxation processes. Two structural damping maxima connected with inverse temperature trend of the modulus occur in the alloys submitted to equal channel angular pressing, the first one is strongly suppresed by Sc and Zr addition. An anelastic relaxation peak whose strength depends on the nature and morphology of precipitates and dispersoids and on the deformation and ageing condition was observed in all samples investigated. The high background damping occurring before the first structural damping maximum is analyzed with reference to a superplastic behavior of the equal channel angular pressing processed alloys.
Authors: A.M. De Sanctis, E. Evangelista, Archimede Forcellese
Authors: Marcello Cabibbo, E. Evangelista, S. Spigarelli, Emanuela Cerri
Authors: Marcello Cabibbo, E. Evangelista, V. Latini, Erik Nes, Stian Tangen
Authors: H.J. McQueen, N.D. Ryan, E. Evangelista
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