Atomic short-range order and spin-glass behaviour in concentrated Cu-Mn alloys

Clad, R.; Kuentzler, R.; Pfeiler, Wolfgang

doi:10.1088/0953-8984/2/31/012

Cited by 11 publications

(3 citation statements)

References 19 publications

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“…Además, la fracción f á de átomos de soluto segregados a las dislocaciones puede evaluarse a partir de: [12] resultando un valor de 0,23. Por lo tanto, al final del proceso de segregación, la concentración residual de soluto c r = c (\-f¿) disponible para el desarrollo de orden disperso, es 0,154.…”

Section: Discussionunclassified

“…Este estado ha sido observado en aleaciones aCu-Al (4-6), aFe-Al (7) y aCu-Zn (1 y 8-10), también se ha reportado en aleaciones aCu-Mn (11)(12)(13)(14). Además, se ha observado que en aleaciones aCu-Al deformadas en frío (15 y 16), la segregación de átomos de soluto hacia las dislocaciones parciales ocurre simultáneamente con el desarrollo de orden disperso.…”

Section: Introductionunclassified

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Competitividad cinética entre el ordenamiento y la segregación de soluto hacia las dislocaciones en Cu-20% at. Mn

Donoso

Varschavsky

1997

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Resumen Utilizando calorimetría diferencial de barrido (DSC), se efectuaron medidas energéticas asociadas con los diferentes eventos térmicos desarrollados durante el calentamiento lineal de Cu-20 % at. Mn, empleando materiales templados y trabajados en frío. Contrariamente a la situación observada en la aleación templada, en la cual se desarrolla orden disperso, en la aleación deformada tal proceso es inhibido por la segregación de átomos de soluto hacia las dislocaciones parciales. Se utilizó un modelo para calcular la energía que se genera durante el proceso de anclaje, con el objeto de determinar la densidad de dislocaciones a partir del efecto exotérmico designado como etapa 4. El valor calculado, el cual está en excelente concordancia con el obtenido a partir de expresiones que gobiernan la energía liberada que acompaña la recristalización, permite verificar, conjuntamente con medidas de microdureza y análisis cinético, que el primer efecto térmico observado en el material deformado efectivamente corresponde a un proceso de segregación de soluto.Palabras clave: Cobre. Manganeso. Microcalorimetría. Dislocaciones. Segregación.Kinetic competitivity between ordering and solute segregation to dislocations in Gu-20 % at. Mn Abstract By using differential scanning calorimetry (DSC), energetic measurements associated with the different peaks displayed during linear heating of Cu-20 % at. Mn were made, employing quenched and cold-worked materials. Unlike to the situation observed in the quenched alloy in which disperse order is developed, in the deformed alloy such process is inhibited by the segregation of solute atoms to partial dislocations. An appropriate model for calculating the energy evolved during the pinning process was applied in order to determine the dislocation density from the exothermic peak designated as stage 4. The computed valué, which is in excellent agreement with the one obtained from expressions governing the energy reléase accompanying recrystallization, allows to verify together with microhardness measurements and kinetic analysis that the first observed thermal effect in the deformed material effectively corresponds to a solute segregation process.

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Section: Discussionunclassified

Section: Introductionunclassified

Competitividad cinética entre el ordenamiento y la segregación de soluto hacia las dislocaciones en Cu-20% at. Mn

Donoso

Varschavsky

1997

REVMETAL

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“…The involvement of lattice defects was demonstrated by Gray and Smith [23,24] and Tustison and Beck [25]. Pfeiler and coworkers [26][27][28][29] found that the SRO relaxation time is unreasonably long below about 200 • C, and that therefore the equilibrium degree of SRO could practically be achieved only by aging above this temperature, where the equilibrium vacancy concentration becomes sufficient to drive the ordering process. The ensuing recommendation [27] that aging should be carried out at T = 210-260 • C discounts the reason for so many aging studies at temperatures near 100 • C, viz.…”

Section: Introductionmentioning

confidence: 99%

A magnetization study of the development of short-range order in a concentrated - Mn spin glass

Gray

1996

J. Phys.: Condens. Matter

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The kinetics of short-range order (SRO) growth in a Cu - 16.4 at.% Mn alloy have been studied by measuring the evolution with time of the low-temperature magnetic properties while aging at temperatures around 100 . This new approach was possible because atomic SRO leads to magnetic clustering at this Mn concentration. Several models, all based on the diffusion of vacancies and their annihilation in fixed sinks, implied that the sink density was higher at 115 than at 100 for identical quenching conditions. It was concluded that the quenched-in vacancies condense in clusters. These act as sinks, halting the growth of SRO when the excess quenched-in vacancies have been absorbed. Quenching faster or aging at a higher temperature nucleates more vacancy clusters, causing earlier vacancy exhaustion. Neutron irradiation was used to continuously supply vacancies, thereby driving the SRO process to equilibrium at about 100 . A much higher magnetic susceptibility was attained than previously reported, some 20 times the as-quenched value at the spin freezing temperature.

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Atomic Short‐Range Order in Cu17 at% Mn

Roelofs

Schönfeld

Kostorz

et al. 1995

Physica Status Solidi (b)

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The elastic diffuse neutron scattering from a Cu 17.2 atoh Mn single crystal aged at 483 K to produce an equilibrium state of atomic short-range order is measured at room temperature in a minimum separation volume of reciprocal space. Warren-Cowley short-range order parameters and coefficients of linear static displacement scattering are determined by least-squares fitting. Effective pair potentials obtained from the short-range order parameters by applying the inverse Monte-Carlo method are used to calculate the diffuse antiphase boundary energy yAPW For copper-base alloys the concentration dependence of yAPe is one of the suggested reasons for the transition of wavy to planar slip. Based on the values of yAPB, the concentration ranges for the transition in Q -M n , CL-AI, and 9 -Z n may be understood.Die elastisch diffuse Neutronenstreuung eines Cu-17,2 At% Mn-Einkristalls, der bei 483 K zur Einstellung eines Gleichgewichtszustandes der atomaren Nahordnung ausgelagert wordcn war, wird bei Zimmertemperatur in einem minimalen Separationsvolumen des reziproken Raums untersucht. Warren-Cowley-Nahordnungsparameter und lineare statische Verzerrungskoeflizienten werden nach der Methode der kleinsten Fehlerquadrate angepaI3t. Aus den Nahordnungsparametern werden effektive Paarpotentiale mit der inversen Monte-Carlo-Methode bestimmt und zur Berechnung der diffusen Antiphasengrenzenergie yApB verwendet. Fur Kupfer-Legierungen wird vorgeschlagen, daR die Konzentrationsabhangigkeit von yAPR den Ubergdng von welliger zu planarer Gleitung bestimmt. Die untcrschiedlichen Konzentrationsbereiche fur diesen Ubergang bei Q-Mn, Q -A 1 und 9 -Z n konnen auf das Verhalten von yApR zuruckgefiihrt werden.

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Atomic short-range order and spin-glass behaviour in concentrated Cu-Mn alloys

Cited by 11 publications

References 19 publications

Competitividad cinética entre el ordenamiento y la segregación de soluto hacia las dislocaciones en Cu-20% at. Mn

Competitividad cinética entre el ordenamiento y la segregación de soluto hacia las dislocaciones en Cu-20% at. Mn

A magnetization study of the development of short-range order in a concentrated - Mn spin glass

Atomic Short‐Range Order in Cu17 at% Mn

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