Étude de l'écoulement plastique de monocristaux filamentaires de fer entre 300 et 4 <sup>°</sup>K Par

Conte, R.; Groh, P.; Escaig, B.

doi:10.1002/pssb.19680280204

Cited by 33 publications

(5 citation statements)

References 28 publications

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“…As was shown by other workers [30,31], this limitation can be considerably reduced by using single crystals with very small diameters (smaller than 1 mm). Therefore, tensile specimens with a diameter of 1 mm were prepared in several steps [24].…”

Section: Methodsmentioning

confidence: 89%

Temperature dependence of the plastic flow of high-purity tungsten single crystals

Brunner

2010

International Journal of Materials Research

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The influence of temperature on the plastic deformation of high-purity tungsten single crystals with an orientation favouring single slip on the (110) or (112) planes, has been studied using tensile tests in the temperature range 26 K to 800 K with emphasis on temperatures below 400 K. The crystals were deformed with an initial applied plastic strain rate of γa = 8.5 · 10−4 s−1 either isothermally until fracture or necking terminated the experiment (called isothermal straining tests) or in small straining intervals at different decreasing temperatures (called isothermal-straining – temperature- lowering tests). After initial plastic deformation at high enough temperatures (T ≥ 650 K; γ ≍ 0.08) tests at lower temperatures (T ≤ 400 K) reveal that the workhardening behaviour changes completely if compared with work-hardening behaviour of tests at the lower temperatures. A combination of tests suggests that work hardening of tungsten cannot be interpreted solely in terms of an increase in the athermal component of the flow stress or an exhaustion of non-screw dislocations. Rather, the results suggest that the different mobilities of screw and non-screw dislocations and their dependence on temperature and strain rate contribute essentially to work hardening at the beginning of plastic flow. Additionally, this is strongly influenced by changes of the slip systems towards the low-temperature regime below about 230 K. Consequences of these features for work hardening and its dependence on temperature, flow stress, critical resolved shear stress are analysed and discussed.

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Section: Methodsmentioning

confidence: 89%

Temperature dependence of the plastic flow of high-purity tungsten single crystals

Brunner

2010

International Journal of Materials Research

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“…Measurements of the temperature dependence of the yield and flow stresses of bodycentred cubic metal crystals of the highest purity show clearly that the predominant part of the increase observed on decreasing the temperature cannot be ascribed to impurity effects, and appears to be due to the Peierls force (Altshuler and Christian 1967, Keh and Nakada 1967, Taylor and Christian 1967. The problem has been considered repeatedly; Guyot and Dorn (1967), Arsenault (1967) and Conte et al (1968) have recently reviewed it in considerable detail. The basis common to the various theoretical treatments is the concept of the formation and propagation of double kinks, i.e.…”

Section: Introductionmentioning

confidence: 99%

The flow stress of body-centred cubic metals at low temperatures

Feltham

1969

J. Phys. D: Appl. Phys.

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Recent measurements on iron single crystals of 99·999% purity, containing less than 0·05 p.p.m. of carbon, show that the strong increase of the flow stress with decreasing temperature in the range 10-300°K is largely independent of small concentrations of interstitial impurities; it appears to be due to the Peierls force. Theoretical considerations employing the double-kink mechanism of dislocation propagation do not account satisfactorily for the observations. A new, simple, model is developed in which dislocation movement is induced by thermally activated formation of curved segments of dislocations trapped in Peierls troughs, the curvature being determined essentially by the effective shear stress. The predominant role of the shear stress in the determination of the curvature of the dislocation segment in the saddle-point configuration is the principal feature differentiating the present model from earlier double-kink treatments. Measurements made on iron and other body-centred cubic metals are successfully explained on the basis of the model.

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“…I1 n'en est pas toujours ainsi, e t oc peut correspondre B des contraintes qui sont encore largement dans le domaine de forte variation thermique. Nous renvoyons pour une comparaison plus precise avec l'experience, aux mesures de Conte et Groh [9] sur des poils de fer, publikes dans ce meme numBro. On peut constater que dans le cas du fer oc est atteint vers 100 OK; dans le niobium [ 5 ] , il l'est vers 150 O K .…”

Section: Discussionunclassified

L'activation thermique des déviations sous faibles contraintes dans les structures h.c. et c.c. Par

Escaig

1968

Physica Status Solidi (b)

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L'activation thermique des deviations sous faibles contraintes dans les structures h.c. et C.C. Par B. ESCAIGDuesbery et Hirsch ont sugg6rir recemment que dans les structures C.C. et h.c., la dkviation d'une dislocation hors de son plan de dissociation, doit se produire i faible contrainte par un mecanisme de double dbcrochement. On montre ici que ce mecanisme doit se produire en dessous d'une contrainte a, = Rlb2, oh R est 1'6nergie de recombinaison et b le vecteur de Burgers de la dislocation; de plus, il n'introduit aucune discontinuit6 de contrainte, d'knergie, ou de volume d'activation. On calciile 1'6nergie d'activation maximum de la deviation correspondant i une composante thermique de la contrainte nulle, pour laquelle on retrouve l'expression donn6e par Duesbery et Hirsch. E n tenant compte de l'interaction 6lastique des decrochements au moyen d'une tension de ligne qui varie logarithmiquenient avec leur distance de ¶tion, on obtient un volume d'activation qui varie en 0-l A faible contrainte a.It is shown that the double kink mechanism proposed by Duesbery and Hirsch for the cross slip in b.c.c. and h.c.p. structures should be operative for stresses smaller than ac = = R/b2, where R is the recombination energy, and b the Burgers vector of the dislocation. The variation of the stress, of the energy or of the activation volume should show no discontinuity a t the transition. The cross slip energy a t zero stress is calculated, in agreement with Duesbery and Hirsch's results. Taking into account the elastic kink interaction through a line tension logarithmically dependent on the kink separation, one finds an activation volume which goes as the inverse of the stress at low stresses.U , E , L sont des fonctions de Ho = hold, h,, ittant la largeur au centre de la

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Étude de l'écoulement plastique de monocristaux filamentaires de fer entre 300 et 4 ^°K Par

Cited by 33 publications

References 28 publications

Temperature dependence of the plastic flow of high-purity tungsten single crystals

Temperature dependence of the plastic flow of high-purity tungsten single crystals

The flow stress of body-centred cubic metals at low temperatures

L'activation thermique des déviations sous faibles contraintes dans les structures h.c. et c.c. Par

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Étude de l'écoulement plastique de monocristaux filamentaires de fer entre 300 et 4 °K Par

Cited by 33 publications

References 28 publications

Temperature dependence of the plastic flow of high-purity tungsten single crystals

Temperature dependence of the plastic flow of high-purity tungsten single crystals

The flow stress of body-centred cubic metals at low temperatures

L'activation thermique des déviations sous faibles contraintes dans les structures h.c. et c.c. Par

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Étude de l'écoulement plastique de monocristaux filamentaires de fer entre 300 et 4 ^°K Par