Documents disponibles écrits par cet auteur

Effect of residual stresses on the onset of yielding in a Zr-based metallic glass / L. Wang in Acta materialia, Vol. 59 N° 20 (Décembre 2011) 

Public ISBD [article]  in Acta materialia > Vol. 59 N° 20 (Décembre 2011) . - pp. 7627–7633 Titre : Effect of residual stresses on the onset of yielding in a Zr-based metallic glass Type de document : texte imprimé Auteurs : L. Wang, Auteur ; H. Bei, Auteur ; Y.F. Gao, Auteur Année de publication : 2012 Article en page(s) : pp. 7627–7633 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Residual  stresses  Onset  of  yielding  Metallic  glasses  Nanoindentation  Glass  transition Résumé : Indentation experiments were performed on as-cast and elastically-bent-and-constrained Zr-based metallic glass samples to investigate the effect of strain rate and residual stresses on the onset of yielding in the material. The critical shear stress for the onset of yielding in the as-cast sample was found to be insensitive to the applied strain rate. By contrast, in the elastically-stressed sample, the maximum contact pressure from the Hertzian stress field at the onset of yielding was found to largely decrease under tensile residual stress, but only slightly increase under compressive residual stress. Despite the different residual stresses, the effective shear stress, i.e. the superimposition of residual and Hertzian stress fields, for the onset of yielding in the Zr-based metallic glass was essentially a constant. The constancy of the effective stress for the onset of yielding was discussed in light of a critical excess volume associated with the atomic structure upon loading. ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645411006665 [article] Effect of residual stresses on the onset of yielding in a Zr-based metallic glass [texte imprimé] / L. Wang, Auteur ; H. Bei, Auteur ; Y.F. Gao, Auteur . - 2012 . - pp. 7627–7633. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 59 N° 20 (Décembre 2011) . - pp. 7627–7633 Mots-clés : Residual  stresses  Onset  of  yielding  Metallic  glasses  Nanoindentation  Glass  transition Résumé : Indentation experiments were performed on as-cast and elastically-bent-and-constrained Zr-based metallic glass samples to investigate the effect of strain rate and residual stresses on the onset of yielding in the material. The critical shear stress for the onset of yielding in the as-cast sample was found to be insensitive to the applied strain rate. By contrast, in the elastically-stressed sample, the maximum contact pressure from the Hertzian stress field at the onset of yielding was found to largely decrease under tensile residual stress, but only slightly increase under compressive residual stress. Despite the different residual stresses, the effective shear stress, i.e. the superimposition of residual and Hertzian stress fields, for the onset of yielding in the Zr-based metallic glass was essentially a constant. The constancy of the effective stress for the onset of yielding was discussed in light of a critical excess volume associated with the atomic structure upon loading. ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645411006665

Effects of boron on the microstructure and thermal stability of directionally solidified NiAl–Mo eutectic / A. Gali in Acta materialia, Vol. 58 N° 2 (Janvier 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 2 (Janvier 2010) . - pp. 421-428 Titre : Effects of boron on the microstructure and thermal stability of directionally solidified NiAl–Mo eutectic Type de document : texte imprimé Auteurs : A. Gali, Auteur ; H. Bei, Auteur ; E.P. George, Auteur Article en page(s) : pp. 421-428 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Interfaces  Segregation  Directional  solidification  Coarsening  Composites Index. décimale : 669 Métallurgie Résumé : Microalloying with 0.01 at.% B decreases the range of growth speeds over which a well-aligned fibrous eutectic microstructure can be obtained in directionally solidified NiAl–Mo. Compared to the undoped alloy, the size/spacing of the Mo fibers is larger, and the fiber density smaller, in the B-doped alloy. Annealing at 1400 °C coarsens the fibers by a mechanism involving fault migration and annihilation driven by diffusion along the fiber–matrix interface. The coarsening kinetics, given by the decrease in Mo fiber density with time, is exponential, and microalloying with B decreases the coarsening rate. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science?_ob=PublicationURL&_tockey=%23TOC%235556%23 [...] [article] Effects of boron on the microstructure and thermal stability of directionally solidified NiAl–Mo eutectic [texte imprimé] / A. Gali, Auteur ; H. Bei, Auteur ; E.P. George, Auteur . - pp. 421-428. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 2 (Janvier 2010) . - pp. 421-428 Mots-clés : Interfaces  Segregation  Directional  solidification  Coarsening  Composites Index. décimale : 669 Métallurgie Résumé : Microalloying with 0.01 at.% B decreases the range of growth speeds over which a well-aligned fibrous eutectic microstructure can be obtained in directionally solidified NiAl–Mo. Compared to the undoped alloy, the size/spacing of the Mo fibers is larger, and the fiber density smaller, in the B-doped alloy. Annealing at 1400 °C coarsens the fibers by a mechanism involving fault migration and annihilation driven by diffusion along the fiber–matrix interface. The coarsening kinetics, given by the decrease in Mo fiber density with time, is exponential, and microalloying with B decreases the coarsening rate. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science?_ob=PublicationURL&_tockey=%23TOC%235556%23 [...]

Effects of Ti, Zr, and Hf on the phase stability of Mo_ss + Mo3Si + Mo5SiB2 alloys at 1600 °C / Ying Yang in Acta materialia, Vol. 58 N° 2 (Janvier 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 2 (Janvier 2010) . - pp. 541-548 Titre : Effects of Ti, Zr, and Hf on the phase stability of Mo_ss + Mo3Si + Mo5SiB2 alloys at 1600 °C Type de document : texte imprimé Auteurs : Ying Yang, Auteur ; H. Bei, Auteur ; Shuanglin Chen, Auteur Article en page(s) : pp. 541-548 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Refractory  metals  Silicides  Multicomponent  phase  equilibrium  CALPHAD  Thermodynamics Index. décimale : 669 Métallurgie Résumé : Understanding the stability of the three-phase Mo_ss + Mo3Si + Mo5SiB2 region is important for alloy design of Mo–Si–B-based refractory metal intermetallic composites. In this work, thermodynamic modeling is coupled with guided experiments to study phase stability in this three-phase region of the Mo–Si–B–X (X = Ti, Zr, Hf) system. Both the calculated and experimental results show that additions of Zr and Hf limit significantly the stability of the three-phase region because of the formation of the ternary phases MoSiZr and MoSiHf, while Ti addition leads to a much larger region of stability for the three-phase equilibrium. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science?_ob=PublicationURL&_tockey=%23TOC%235556%23 [...] [article] Effects of Ti, Zr, and Hf on the phase stability of Mo_ss + Mo3Si + Mo5SiB2 alloys at 1600 °C [texte imprimé] / Ying Yang, Auteur ; H. Bei, Auteur ; Shuanglin Chen, Auteur . - pp. 541-548. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 2 (Janvier 2010) . - pp. 541-548 Mots-clés : Refractory  metals  Silicides  Multicomponent  phase  equilibrium  CALPHAD  Thermodynamics Index. décimale : 669 Métallurgie Résumé : Understanding the stability of the three-phase Mo_ss + Mo3Si + Mo5SiB2 region is important for alloy design of Mo–Si–B-based refractory metal intermetallic composites. In this work, thermodynamic modeling is coupled with guided experiments to study phase stability in this three-phase region of the Mo–Si–B–X (X = Ti, Zr, Hf) system. Both the calculated and experimental results show that additions of Zr and Hf limit significantly the stability of the three-phase region because of the formation of the ternary phases MoSiZr and MoSiHf, while Ti addition leads to a much larger region of stability for the three-phase equilibrium. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science?_ob=PublicationURL&_tockey=%23TOC%235556%23 [...]