Центральная Научная Библиотека УрО РАН

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   M 46

    Medvedeva, N. I.
    Solid solution softening and hardening in the group-V and group-VI bcc. transition metals alloys: First principles calculations and atomistic modeling [Текст] / N. I. Medvedeva, Yu. N. Gornostyrev, A. J. Freeman // Physical Review B: Condensed Matter and Materials Physics. - 2007. - Vol. 76, № 21. - С. 212104/1-212104/4. - Библиогр. : с. 212104/4 (31 назв.)

ББК 54
Рубрики: ХИМИЧЕСКИЕ НАУКИ
Кл.слова (ненормированные):
СПЛАВЫ -- ПЕРЕХОДНЫЕ МЕТАЛЛЫ -- ПЕРВОПРИНЦИПНЫЕ ЗОННЫЕ РАСЧЕТЫ -- ТВЕРДЫЕ РАСТВОРЫ
Аннотация: The interaction of d transition metal additions with dislocations was studied in bcc alloys by using the atomic row model with ab initio parametrization of the interatomic interactions. Opposite trends were obtained for the solute-dislocation interactions in the group-V (Nb, Ta) and group-VI (Mo, W) bcc metals: while additions with extra valence electrons enhance the double-kink nucleation and result in solid solution softening in the group-VI metals, they cannot cause the intrinsic softening in the group-V metals. Oppositely, additions with fewer valence electrons should lead to an intrinsic softening in the group-V metals and a strong hardening in the group-VI metals. The effect of electronic concentration on the solute-dislocation interaction is less pronounced in the group-V alloys, and other mechanisms may be dominant in their softening and hardening behavior

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   M 46

    Medvedeva, N. I.
    Solid solution softening in bcc Mo alloys: Effect of transition-metal additions on dislocation structure and mobility [Текст] / N. I. Medvedeva, Yu. N. Gornostyrev, A. J. Freeman // Physical Review B: Condensed Matter and Materials Physics. - 2005. - Vol. 72, № 13. - С. 134107/1-134107/9. - Библиогр. : с. 134107/9 (55 назв.)

ББК 54
Рубрики: ХИМИЧЕСКИЕ НАУКИ
Кл.слова (ненормированные):
ТВЕРДЫЕ РАСТВОРЫ -- МОЛИБДЕН -- СПЛАВЫ
Аннотация: The electronic origin of solid solution softening (SSS) in bcc molybdenum alloys was investigated in the framework of a combined approach that includes atomistic dislocation modeling with first principles parametrization of interatomic interactions. The softening additions are found to locally change the chemical bonding which results in a decrease of the generalized stacking fault (GSF) energy and atomic row shear resistance. Using the atomic row model, we show that the isotropic core of the screw dislocation in Mo tends to a “split” (planar) core under alloying with softener solutes (Re, Os, Ir, Pt). The generalized Peierls-Nabarro model for a non-planar core was employed to link the reduction in GSF energy with the enhancement of double kink nucleation and dislocation mobility. Our study appears to explain the experimental dependence of the alloying effect on the atomic number of the addition and to provide an understanding of the electronic reasons for SSS in Mo alloys

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   M 46

    Medvedeva, N. I.
    Electronic Origin of Solid Solution Softening in body centered cubic Molybdenum Alloys [Текст] / N. I. Medvedeva, Yu. N. Gornostyrev, A. J. Freeman // Physical Review Letters. - 2005. - Vol. 94, № 13. - С. 136402/1-136402/4. - Библиогр. : с. 136402/4 (35 назв.)

ББК 54
Рубрики: ХИМИЧЕСКИЕ НАУКИ
Кл.слова (ненормированные):
ТВЕРДЫЕ РАСТВОРЫ -- СПЛАВЫ МОЛИБДЕНА -- МОЛИБДЕН
Аннотация: The intrinsic mechanism of solid solution softening in bcc molybdenum alloys due to 5d transition metal additions is investigated on the basis of ab initio electronic-structure calculations that model the effect of alloying elements on the generalized stacking fault (GSF) energies. We demonstrate that additions with an excess of electrons (Re, Os, Ir, and Pt) lead to a decrease in the GSF energy and those with a lack of electrons (Hf and Ta) to its sharp increase. Using the generalized Peierls-Nabarro model for a nonplanar core, we associate the local reduction of the GSF energy with an enhancement of double kink nucleation and an increase of the dislocation mobility, and we reveal the electronic reasons for the observed dependence of the solution softening on the atomic number of the addition

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