“Stage III” recovery in cold-worked iron

Cuddy, L. J.; Raley, J. C.

doi:10.1016/0001-6160(66)90106-4

Cited by 23 publications

(5 citation statements)

References 6 publications

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“…Their annihilation a t inexhaustible sinks corresponds to a first-order reaction, and this is what we found for stage IV. The number of vacancies may be calculated from the height of this stage, assuming a resistivity increment of Ap = R cmlatyo vacancies [8]. The data of the specimen with R, = 720 (Fig.…”

Section: Such a Migration Obeys A First-order Kinetic Law Id Agreemenmentioning

confidence: 99%

Quenching Experiments with High‐Purity Iron

Glaeser

Wever

1969

Physica Status Solidi (b)

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Iron wire of very high purity was quenched in a helium cryostat. Changes in electrical resistivity were used t o measure the recovery during isochronal and isothermal annealing in the temperature range 4.2 to 1000 OK. Two sharp recovery stages were observed (first stage: 300 "K < T < 400 OK, second stage: 400 O K < T < 520 O K ) . The activation energy was determined by the change in slope and the Meechan-Brinkman test (first stage: 0.48 t o 0.51 eV, second stage: 1.05 to 1.1 eV). Both recovery processes follow afirst-order kinetic law. These two stages are observed after cold work as well. The first stage is attributed to the migration of carbon atoms alone and paired with vacancies, the second stage corresponds to the migration of vacancies. The recovery spectrum exhibits in three different temperature ranges a resistivity increase and a final recovery stage in the range 850 to 1000 "K. The last increase and recovery stage may be due either to the redissolution of carbon atoms or to Bloch wall motion.Eisendraht hochster Reinheit wurde im Helium-Kryostaten abgeschreckt. Die h d e r u ngen des elektrischen Widerstandes wurden gemessen, um die Erholung wLhrend isochroner und isothermer Gliihungen im Temperaturbereich von 4,2 bis 1000 O K zu verfolgen. Zwei scharfe Erholungsstufen wurden beobachtet (die erste Stufe bei 300 OK < T < 400 OK, die zweite Stufe bei 400 O K < T 4 520 OK). Die Aktivierungsenergie wurde bestimmt durch das Tangenten-Steigungsverfahren und das Meechan-Brinkman-Verfahren (erste Stufe: 0,48 bis 0,51 eV, zweite Stufe: 1,05 bis 1,l eV). Beide Erholungsvorgange entsprechen einer Reaktionsordnung ersten Grades. Diese beiden Stufen werden auch nach Kaltverformung beobachtet. Die erste Stufe wird der Wanderung von Kohlenstoffatomen allein und gepaart mit Leerstellen zugeordnet, die zweite Stufe entspricht der Wanderung von Leerstellen. Das Erholungsspektrum zeigt in drei verschiedenen Temperaturbereichen einen Widerstandsanstieg ebenso wie eine weitere Erholungsstufe in dem Bereich von 850 bis 1000 O K . Dieser Anstieg und die Erholungsstufe sind entweder auf die Losung von Kohlenstoffatomen oder auf Bloch-Wandbewegung zuriickzufiihren. l) Present address : Department of Physics, University of the Witwatersrand, Johannesburg, South Africa.

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Section: Such a Migration Obeys A First-order Kinetic Law Id Agreemenmentioning

confidence: 99%

Quenching Experiments with High‐Purity Iron

Glaeser

Wever

1969

Physica Status Solidi (b)

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“…7 from which the activation energies for peaks A, B, and C are found to be respectively, (0.69 & 0.04) eV, (0.63 2 0.04) eV, and (1. 16 Consider peaks A and B. Both have similar activation energies which may be simply explained if the same defect migrates in the two cases.…”

Section: Identification Of Defectsmentioning

confidence: 98%

Strain Aging of Niobium in the Temperature Range 100 to 200 °C

Soo

1969

Physica Status Solidi (b)

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Strain aging experiments have been conducted on polycrystalline niobium, containing approximately 100 ppm by weight of interstitial impurities. For aging temperatures in the so-called stage I11 recovery region, which lies between 100 to 200 "C, recovery occurs in two separate and independent substages. The first substage is thought to be caused by the detrapping of self-interstitials which are then able to migrate through the lattice and form new defect configurations. The second substage is probably connected with the migration of oxygen interstitials. The study indicates that the pinning of dislocations may also occur during the recovery and, under suitable conditions, dislocations may be sucoessively pinned by self-interstitials, oxygen interstitials, and carbon (or nitrogen) interstitials.Deformationsalterungsexperimente wurden an polykristallinem Niobium durchgefuhrt, das ungefiihr 100 ppm (Gew.) Zwischengitterverunreinigungen enthielt. Fur Alterungstemperaturen im Bereich des sog. Erholungszustands 111, der zwischen 100 und 200°C liegt, tritt die Erholung in zwei getrennten und unabhangigen Unterzustiinden auf. Es wird angenommen, daB der erste Subzustand durch Detrapping von Zwischengitterdefekten verursacht wird, die dann durch das Gitter wandern und neue Defektanordnungen bilden konnen. Der zweite Subzustand ist wahrscheinlich mit der Wanderung von Sauerstloff auf Zwischengitterplatz verbunden. Es wird gezeigt, daB die Verankerung von Verset,zungen auch wahrend der Erholung auftreten kann, und daB unter geeigneten Bedingungen die Versetzungen sukzessive durch Zwischengittereigendefekte, Sauerstoffzwischengitterdefekte und Kohlenstoff-(oder Stickstoff-)zwischengitterdefekte verankert werden konnen.

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“…It is well known that plastic deformation changes dislocation density and distribution, which induces changes in electrical resistivity,' 5,16 While using PDM to register crack lengths, these changes of electrical resistivity might influence the result. Therefore, we are making a rough estimation here of these effects as compared with the effects of crack growth and overall (deformation.…”

Section: Appendixmentioning

confidence: 99%

Crack length measurements with a potential drop method: A finite element simulation

Ståhle

1993

Numerical Meth Engineering

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A potential drop method, as used for estimations of crack lengths during three-point-bend experiments, is studied. The mechanical slate is calculated using a finite element method. The deformed body obtained is used for a subsequent calculation of the electrostatic state. Calculations are performed for both two-and three-dimensional models. The material is assumed to be elastic, linearly hardening plastic and electrostatically linear. Large deformations are considered. Further, the non-linearity caused by the load, depending on the contact area between the cylinder on which the load is applied and the specimen, is considered. The increased contact area did not influence the mechanical state very much but had a direct impact on the electrostatic state. The changes in the potential drop recordings due to deformation and electrical current passing through the load cylinder were shown to be considerable. The study explains, at least partly, the experimental observations. A more reliable registration of crack growth initiation is the main outcome of the analysis.

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“Stage III” recovery in cold-worked iron

Cited by 23 publications

References 6 publications

Quenching Experiments with High‐Purity Iron

Quenching Experiments with High‐Purity Iron

Strain Aging of Niobium in the Temperature Range 100 to 200 °C

Crack length measurements with a potential drop method: A finite element simulation

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