Locking of Dislocations without the Application of an External Stress: Experiment and Theory

Greenberg, B. A.; Ivanov, M. O.; Антонова, О. В.; Пацелов, А. М.; Plotnikov, A. E.; Vlasova, A. M.

doi:10.15407/ufm.14.02.107

Cited by 6 publications

(5 citation statements)

References 54 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Then, after removing the load, the samples were slowly cooled (with a furnace) for ~1 h. As was shown in [3], this treatment ("slow cooling") is equiv alent to heating without load.…”

Section: Resultsmentioning

confidence: 99%

“…Self block ing is confirmed by the transformation of curvilinear dislocations into straight line ones and their extension along a selected direction upon heating without load. Dislocation self blocking was found in intermetallic compounds Ni 3 (Al, Nb), TiAl, and (later) Ni 3 (Ge) [3,4]. Self blocking was believed to be possible in only intermetallic compounds because of the complex internal structure of superdislocation.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The first observation of dislocation blocking in pure metal without external stress

et al. 2012

Self Cite

View full text Add to dashboard Cite

“…Then, after removing the load, the samples were slowly cooled (with a furnace) for ~1 h. As was shown in [3], this treatment ("slow cooling") is equiv alent to heating without load.…”

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The first observation of dislocation blocking in pure metal without external stress

et al. 2012

Self Cite

View full text Add to dashboard Cite

“…The self-blocking was proved by dislocation extension along the preferred direction and observation of rectilinear dislocations after stress-free heating. The self-blocking of dislocations in Ni 3 (Al, Nb) and TiAl intermetallides [2] as well as in Ni 3 Ge [3] was established. It is well known [4,5] that in these intermetallides, the anomalous temperature behavior of the yield stress σ y (T) is observed.…”

Section: Introductionmentioning

confidence: 93%

“…Single crystals were subject to shrinkage strain by 1.5-2.0% with a rate of the order of 0.3 mm/min at the temperature Т = 150ºС. Then, when loading had been removed, they were cooled slowly in a furnace for about 1 h. As demonstrated in [3], such processing (slow temperature decay) is equivalent to stress-free heating.…”

Section: Samples and Proceduresmentioning

confidence: 99%

Detection of (C + A)-type dislocation self-blocking in magnesium

et al. 2011

Self Cite

View full text Add to dashboard Cite

The self-blocking effect predicted theoretically and then observed in intermetallides is established for a pure metal, namely, for magnesium. This effect can be observed only for magnesium single crystals whose axis is parallel to the c axis and whose yield stress behavior σ y (T) has a temperature anomaly. For such single crystals, the self-blocking of the (c + a)-type edge dislocations is established during pyramidal slip of type II. The self-blocking is proved by dislocation extension along the preferred direction without external stress. In this case, the < 1100 > directions appear preferred. TEM images of (c + a) dislocations extended along the preferred directions are presented. It is demonstrated that two effects -temperature anomaly of σ y (T) and dislocation self-blocking -have the common nature: a two-valley potential relief of the dislocation. A model of two-valley relief of the (c + a) dislocations in Mg is proposed.

show abstract

“…Whereas in pure metals and disordered solid solutions the standard behavior with temperature increase is associated with decreased mechanical characteristics, a positive temperature dependence of the flow stress [2][3][4][5] called in the literature the temperature anomaly of the mechanical properties is manifested for a number of alloys with the L1 2 superstructure. This anomalous mechanical behavior is caused by superdislocations existing in the alloys, their motion, and self-blocking [6,7]. The temperature influences on the resistance to dislocation motion in two ways.…”

mentioning

confidence: 99%

Cottrell−Stokes Law for Ni3Ge Intermetallic Single Crystals with the [ 2 ¯ $$ \overline{2} $$ 3 4] Compression Axis

et al. 2015

View full text Add to dashboard Cite

In an experiment on the temperature variation during plastic deformation of Ni 3 Ge alloy single crystals with the [ 2 3 4] orientation of the deformation axis, a dependence of the stress jump on the applied stress is investigated. It is elucidated that under conditions of cubic slip, the dependence is linear and is similar to that observed for pure metals (the Cottrell−Stokes law). The anomalous temperature dependence of the flow stress during cubic slip is confirmed in experiments on the variation of the deformation temperature.Metal alloys are widely used in all fields of technical and scientific activity. They possess a wide spectrum of operational characteristics allowing them to be used at different temperatures and stresses. The temperature variation during deformation impact leads to the change of the material state and to the occurrence of stress jumps. It was established that the stress jumps attendant to the temperature variation depend on the stress and temperature. This dependence is well described by the linear relationship of the formThis interrelation called the Cottrell−Stokes law [1] was established for pure metals and disordered solid solutions. Whereas in pure metals and disordered solid solutions the standard behavior with temperature increase is associated with decreased mechanical characteristics, a positive temperature dependence of the flow stress [2-5] called in the literature the temperature anomaly of the mechanical properties is manifested for a number of alloys with the L1 2 superstructure. This anomalous mechanical behavior is caused by superdislocations existing in the alloys, their motion, and self-blocking [6,7]. The temperature influences on the resistance to dislocation motion in two ways. On the one hand, thermal fluctuations help the applied stress to move dislocations through obstacles, and from the other hand, they activate superdislocation self-blocking. The change of the plastic deformation carriers changes also the mechanisms of the deformation processes; therefore, the patterns of these processes can also change. In this regard, it is interesting to elucidate whether the Cottrell−Stokes law is valid for ordered alloys.It is expedient to investigate the influence of temperature variation during the deformation on the ordered alloys well studied in different aspects. The Ni 3 Ge alloy for which we performed extensive cycle of investigations [8][9][10][11][12][13][14] is among them. The study of the Ni 3 Ge single crystals with the L1 2 ordered superstructure demonstrated that the Cottrell−Stokes law was valid for samples deformed along the [001] [15] and [ 1 3 9] axes [16]. However, it is necessary to find whether this law is valid for other orientations and to elucidate conditions under which it is valid.

show abstract

Locking of Dislocations without the Application of an External Stress: Experiment and Theory

Cited by 6 publications

References 54 publications

The first observation of dislocation blocking in pure metal without external stress

The first observation of dislocation blocking in pure metal without external stress

Detection of (C + A)-type dislocation self-blocking in magnesium

Cottrell−Stokes Law for Ni3Ge Intermetallic Single Crystals with the [ 2 ¯ $$ \overline{2} $$ 3 4] Compression Axis

Contact Info

Product

Resources

About