Die Aktivierungsenergie für die Quergleitung aufgespaltener Schraubenversetzungen

Wolf, Helmut

doi:10.1515/zna-1960-0302

Cited by 76 publications

(6 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Our purpose is to demonstrate the general role of alloying on cross-slip across a range of FCC alloys by using model alloy materials over a wide range of solute concentrations. Here, we consider alloys of Al+ (2,6,10,14,18,22) at.% Mg, Ni+ (2,4,8,10,12,15) at.% Al and Cu+ (10,22,33,68,79,90) at.% Ni as described by the EAM potentials for Al-Mg [74], Ni-Al [75], and Cu-Ni [76]. While these model materials may exceed the solute concentrations of the corresponding real alloy materials (e.g.…”

Section: Selected Alloysmentioning

confidence: 99%

Dislocation cross-slip in fcc solid solution alloys

Nöhring

Curtin

2017

Acta Materialia

View full text Add to dashboard Cite

Cross-slip is a fundamental process of screw dislocation motion and plays an important role in the evolution of work hardening and dislocation structuring in metals. Cross-slip has been widely studied in pure FCC metals but rarely in FCC solid solutions. Here, the cross-slip transition path in solid solutions is calculated using atomistic methods for three representative systems of Ni-Al, Cu-Ni and Al-Mg over a range of solute concentrations. Studies using both true random alloys and their corresponding average-alloy counterparts allows for the independent assessment of the roles of (i) fluctuations in the spatial solute distribution in the true random alloy randomness and (ii) average alloy properties such as stacking fault energy. The results show that the solute fluctuations dominate the activation energy barrier, i.e. there are large sample-to-sample variations around the average activation barrier. The variations in activation barrier correlate linearly with the energy difference between the initial and final states. The distribution of this energy difference can be computed analytically in terms of the solute/dislocation interaction energies. Thus, the distribution of cross-slip activation energies can be accurately determined from a parameter-free analytic model. The implications of the statistical distribution of activation energies on the rate of cross-slip in real alloys are then identified.

show abstract

Section: Selected Alloysmentioning

confidence: 99%

Dislocation cross-slip in fcc solid solution alloys

Nöhring

Curtin

2017

Acta Materialia

View full text Add to dashboard Cite

show abstract

“…The characteristics of the stress dependence of Δ U cs (σ, P ) differ with the controlling step in cross slip: constriction or dissociation of partials. Wolf [1960; see also Skrotzki and Liu , 1982] presented a model in which constriction forms the basic rate‐controlling process. In this model, the activation energy Δ U cs (σ, P ) is expressed:

where μ is the shear modulus at temperature T , μ 0 and σ 0 are the shear modulus and flow stress at T = 0 K, and Δ U cs is a proportionality constant related to the stacking fault energy γ.…”

Section: Microphysical Models Of Creep Controlled By Dislocation Climmentioning

confidence: 99%

“…In this model, the activation energy Δ U cs (σ, P ) is expressed:

where μ is the shear modulus at temperature T , μ 0 and σ 0 are the shear modulus and flow stress at T = 0 K, and Δ U cs is a proportionality constant related to the stacking fault energy γ. For FCC materials, Δ U cs for large γ can be approximated by [ Wolf , 1960]:

where β depends on the elastic anisotropy of the material. According to Seeger [1956], β = 2 C 44 /2π( C 11 − C 12 ) (FCC materials), where C ij represent the relevant elastic constants of the material.…”

Section: Microphysical Models Of Creep Controlled By Dislocation Climmentioning

confidence: 99%

“…[9] The characteristics of the stress dependence of ÁU cs (s, P) differ with the controlling step in cross slip: constriction or dissociation of partials. Wolf [1960; see also Skrotzki and Liu, 1982] presented a model in which constriction forms the basic rate-controlling process. In this model, the activation energy ÁU cs (s, P) is expressed:…”

Section: Cross-slip-controlled Creepmentioning

confidence: 99%

“…where m is the shear modulus at temperature T, m 0 and s 0 are the shear modulus and flow stress at T = 0 K, and ÁU cs is a proportionality constant related to the stacking fault energy g. For FCC materials, ÁU cs for large g can be approximated by [Wolf, 1960]:…”

Section: Cross-slip-controlled Creepmentioning

confidence: 99%

See 2 more Smart Citations

On the mechanism of dislocation creep of calcite at high temperature: Inferences from experimentally measured pressure sensitivity and strain rate sensitivity of flow stress

Bresser

2002

J. Geophys. Res.

View full text Add to dashboard Cite

[1] Previous laboratory experiments on coarse grained calcite materials at intermediate conditions of stress and temperature have shown low strain rate sensitivity of flow stress, expressed by standard power law stress exponents n ! 7. This conflicts with conventional models for creep controlled by dislocation climb (n = 3-4.5), a recovery mechanism widely used to explain steady-state dislocation creep. This paper addresses the question whether dislocation cross slip rather than climb is the mechanism controlling creep of calcite at intermediate conditions. New uniaxial compression tests were performed on calcite single crystals and Carrara marble at T = 800-1000°C, _ e = 10 À4 -2 Â 10 À7 s À1, and P = 100-600 MPa. Emphasis was on the pressure (P) and strain rate (_ e) sensitivity of flow stress, because these form potential ways for discriminating between climb and cross slip models. Both single crystals and Carrara marble demonstrated a small increase in flow stress with increasing pressure ($1.6% per 100 MPa) at constant strain rate and temperature. The low strain rate sensitivity of flow stress was confirmed, though n gradually changes with stress or temperature rather than taking a constant value. Evaluation of the experimental data against microphysical models indicated that cross slip controlled by dissociation of dislocations offers the best explanation for the observed mechanical behavior. If the associated creep equation is used to estimate flow stresses under natural conditions, the resulting values at T < 500°C are substantially less than those following from previous flow laws. The influence of pressure on the behavior of marble, however, can be safely ignored for most practical purposes.INDEX TERMS: 3902 Mineral Physics: Creep and deformation; 3904 Mineral Physics: Defects; 5120 Physical Properties of Rocks: Plasticity, diffusion, and creep; 8159 Tectonophysics: Evolution of the Earth: Rheology-crust and lithosphere; KEYWORDS: calcite, dislocation cross slip, pressure, creep Citation: De Bresser, J. H. P., On the mechanism of dislocation creep of calcite at high temperature: Inferences from experimentally measured pressure sensitivity and strain rate sensitivity of flow stress,

show abstract

Thermally activated cross slip of screw dislocations in Ge

Möller

Haasen

1976

Phys. Stat. Sol. (a)

View full text Add to dashboard Cite

Die Aktivierungsenergie für die Quergleitung aufgespaltener Schraubenversetzungen

Cited by 76 publications

References 0 publications

Dislocation cross-slip in fcc solid solution alloys

Dislocation cross-slip in fcc solid solution alloys

On the mechanism of dislocation creep of calcite at high temperature: Inferences from experimentally measured pressure sensitivity and strain rate sensitivity of flow stress

Thermally activated cross slip of screw dislocations in Ge

Contact Info

Product

Resources

About