Documents disponibles écrits par cet auteur

Core–shell nanoscale precipitates in Al–0.06 at.% Sc microalloyed with Tb, Ho, Tm or Lu / Matthew E. Krug in Acta materialia, Vol. 58 N° 1 (Janvier 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 1 (Janvier 2010) . - pp. 134–145 Titre : Core–shell nanoscale precipitates in Al–0.06 at.% Sc microalloyed with Tb, Ho, Tm or Lu Type de document : texte imprimé Auteurs : Matthew E. Krug, Auteur ; Alexandra Werber, Auteur ; David C. Dunand, Auteur Année de publication : 2010 Article en page(s) : pp. 134–145 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Rare  earth  Precipitation  Microhardness  Atom-probe  field-ion  microscopy  (AP-FIM)  Aluminum  alloys Résumé : The age-hardening response at 300 °C of Al–0.06Sc–0.02RE (at.%, with RE = Tb, Ho, Tm or Lu) is found to be similar to that of binary Al–0.08Sc (at.%), except that a shorter incubation period for hardening is observed, which is associated with nanoscale RE-rich Al3(RE1−xScx) precipitates. In addition, Al–0.06Sc–0.02Tb (at.%) has a much lower peak microhardness than that of Al–0.08Sc (at.%) due to the small solubility of Tb in α-Al(Sc). Peak-age hardening occurs after 24 h, and is associated with a high number density of nanoscale Sc-rich Al3(Sc1−xREx) precipitates. Analysis by three-dimensional local-electrode atom-probe tomography shows that x increases with increasing atomic number, and that the REs partition to the core of the precipitates. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645409005874 [article] Core–shell nanoscale precipitates in Al–0.06 at.% Sc microalloyed with Tb, Ho, Tm or Lu [texte imprimé] / Matthew E. Krug, Auteur ; Alexandra Werber, Auteur ; David C. Dunand, Auteur . - 2010 . - pp. 134–145. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 1 (Janvier 2010) . - pp. 134–145 Mots-clés : Rare  earth  Precipitation  Microhardness  Atom-probe  field-ion  microscopy  (AP-FIM)  Aluminum  alloys Résumé : The age-hardening response at 300 °C of Al–0.06Sc–0.02RE (at.%, with RE = Tb, Ho, Tm or Lu) is found to be similar to that of binary Al–0.08Sc (at.%), except that a shorter incubation period for hardening is observed, which is associated with nanoscale RE-rich Al3(RE1−xScx) precipitates. In addition, Al–0.06Sc–0.02Tb (at.%) has a much lower peak microhardness than that of Al–0.08Sc (at.%) due to the small solubility of Tb in α-Al(Sc). Peak-age hardening occurs after 24 h, and is associated with a high number density of nanoscale Sc-rich Al3(Sc1−xREx) precipitates. Analysis by three-dimensional local-electrode atom-probe tomography shows that x increases with increasing atomic number, and that the REs partition to the core of the precipitates. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645409005874

Effects of Yb and Zr microalloying additions on the microstructure and mechanical properties of dilute Al–Sc alloys / Marsha E. Van Dalen in Acta materialia, Vol. 59 N° 20 (Décembre 2011) 

Public ISBD [article]  in Acta materialia > Vol. 59 N° 20 (Décembre 2011) . - pp. 7615–7626 Titre : Effects of Yb and Zr microalloying additions on the microstructure and mechanical properties of dilute Al–Sc alloys Type de document : texte imprimé Auteurs : Marsha E. Van Dalen, Auteur ; Thomas Gyger, Auteur ; David C. Dunand, Auteur Année de publication : 2012 Article en page(s) : pp. 7615–7626 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Aluminum  alloys  Nucleation  Precipitation  Coarsening  Creep Résumé : It is known that Zr and Yb partition to the Al3Sc precipitates created during aging when microalloyed separately in dilute binary Al–Sc alloys. Addition of Zr delays precipitate coarsening, thereby improving the coarsening resistance of the ternary Al-Sc-Zr alloys. Addition of Yb increases the resistance against dislocation climb, thereby improving the creep resistances of the ternary Al-Sc-Yb alloys. A combination of microhardness, creep, and atom probe tomography measurements provide evidence that these effects of Zr and Yb additions are cumulative in quaternary dilute Al–Sc–Yb–Zr alloys: Yb increases their creep resistance at 300 °C compared with ternary Al–Sc–Zr alloys and Zr improves their coarsening resistance at 300 °C compared with ternary Al–Sc–Yb alloys. Additionally, excellent coarsening resistance is observed at 350 and 375 °C. ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645411006562 [article] Effects of Yb and Zr microalloying additions on the microstructure and mechanical properties of dilute Al–Sc alloys [texte imprimé] / Marsha E. Van Dalen, Auteur ; Thomas Gyger, Auteur ; David C. Dunand, Auteur . - 2012 . - pp. 7615–7626. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 59 N° 20 (Décembre 2011) . - pp. 7615–7626 Mots-clés : Aluminum  alloys  Nucleation  Precipitation  Coarsening  Creep Résumé : It is known that Zr and Yb partition to the Al3Sc precipitates created during aging when microalloyed separately in dilute binary Al–Sc alloys. Addition of Zr delays precipitate coarsening, thereby improving the coarsening resistance of the ternary Al-Sc-Zr alloys. Addition of Yb increases the resistance against dislocation climb, thereby improving the creep resistances of the ternary Al-Sc-Yb alloys. A combination of microhardness, creep, and atom probe tomography measurements provide evidence that these effects of Zr and Yb additions are cumulative in quaternary dilute Al–Sc–Yb–Zr alloys: Yb increases their creep resistance at 300 °C compared with ternary Al–Sc–Zr alloys and Zr improves their coarsening resistance at 300 °C compared with ternary Al–Sc–Yb alloys. Additionally, excellent coarsening resistance is observed at 350 and 375 °C. ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645411006562

Enhanced densification of Ti–6Al–4V powders by transformation-mismatch plasticity / Bing Ye in Acta materialia, Vol. 58 N° 11 (Juin 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 11 (Juin 2010) . - pp. 3851–3859 Titre : Enhanced densification of Ti–6Al–4V powders by transformation-mismatch plasticity Type de document : texte imprimé Auteurs : Bing Ye, Auteur ; Marc R. Matsen, Auteur ; David C. Dunand, Auteur Année de publication : 2011 Article en page(s) : pp. 3851–3859 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Powder  consolidation  Hot  pressing  Titanium  Phase  transformations  Superplasticity Résumé : The densification kinetics of Ti–6Al–4V powders with spherical or angular shapes are compared in uniaxial die pressing experiments between isothermal conditions (at 1020 °C, in the β-field, where deformation occurs by creep) and thermal cycling (between 860 and 1020 °C, within the range of the α–β phase transformation of the alloy, where transformation-mismatch plasticity is activated). Densification kinetics are only moderately affected by powder shape, but are markedly faster under thermal cycling than under isothermal conditions, as expected from the higher deformation rate achieved under transformation-mismatch plasticity conditions as compared to creep conditions. The densification curves for both creep and mismatch plasticity deformation mechanisms are successfully modeled for various applied stresses and for partial cycling, when transformation is incomplete. Tensile properties of specimens fully densified under thermal cycling conditions are similar to literature values from Ti–6Al–4V densified by isothermal hot isostatic pressing. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645410002053 [article] Enhanced densification of Ti–6Al–4V powders by transformation-mismatch plasticity [texte imprimé] / Bing Ye, Auteur ; Marc R. Matsen, Auteur ; David C. Dunand, Auteur . - 2011 . - pp. 3851–3859. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 11 (Juin 2010) . - pp. 3851–3859 Mots-clés : Powder  consolidation  Hot  pressing  Titanium  Phase  transformations  Superplasticity Résumé : The densification kinetics of Ti–6Al–4V powders with spherical or angular shapes are compared in uniaxial die pressing experiments between isothermal conditions (at 1020 °C, in the β-field, where deformation occurs by creep) and thermal cycling (between 860 and 1020 °C, within the range of the α–β phase transformation of the alloy, where transformation-mismatch plasticity is activated). Densification kinetics are only moderately affected by powder shape, but are markedly faster under thermal cycling than under isothermal conditions, as expected from the higher deformation rate achieved under transformation-mismatch plasticity conditions as compared to creep conditions. The densification curves for both creep and mismatch plasticity deformation mechanisms are successfully modeled for various applied stresses and for partial cycling, when transformation is incomplete. Tensile properties of specimens fully densified under thermal cycling conditions are similar to literature values from Ti–6Al–4V densified by isothermal hot isostatic pressing. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645410002053