Temperature Dependence of Positron Trapping to Dislocations in Deformed Zinc

Hashimoto, Eiji

doi:10.1143/jpsj.62.552

Cited by 8 publications

(3 citation statements)

References 5 publications

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“…10.1). The transition rates between the states depend on the temperature and can be described by a three state trapping model [24,25,27,28] that is consistent with many experiments (for example [29]). Additionally, dislocations may act as fast diffusion paths for positrons, which enhances their sensitivity to vacancy-like defects [29].…”

Section: The Search For Defects: Positrons In Solidssupporting

confidence: 74%

Predicting the Lifetime of Steel

Haaks

Maier

Extreme Events in Nature and Society

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Section: The Search For Defects: Positrons In Solidssupporting

confidence: 74%

Predicting the Lifetime of Steel

Haaks

Maier

Extreme Events in Nature and Society

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“…13,14,16,19 In positron lifetime measurements performed at 77 K after tensile deformation of ␣-iron single crystals at 200 K Park et al 22 could determine separately the densities of screw and edge dislocations after identifying positron lifetimes of 165 and 143 ps for positrons trapped in edge and screw dislocations, respectively. This agrees with earlier findings that the lifetime of positrons trapped in the dilatational zone of an edge dislocation at low temperature is just slightly smaller than that of a single vacancy in the same material.…”

Section: B Positron Annihilation In Plastically Deformed Metalsmentioning

confidence: 99%

Nondestructive monitoring of fatigue damage evolution in austenitic stainless steel by positron-lifetime measurements

Holzwarth

Schaaff

2004

Phys. Rev. B

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Positron-lifetime measurements have been performed on austenitic stainless steel during ͑i͒ stress-and ͑ii͒ strain-controlled fatigue experiments for different applied stress and strain amplitudes, respectively. For this purpose a generator-detector assembly with a 72 Se/ 72 As positron generator ͓maximum activity 25 Ci ͑0.9 MBq͔͒ has been mounted on mechanical testing machines in order to measure the positron lifetime without removing the specimens from the load train. The average positron lifetime has been determined by a ␤ ϩ Ϫ␥ coincidence. The feasibility to use the average positron lifetime for monitoring the evolution of fatigue damage and to predict early failure has been examined. In strain-and stress-controlled experiments the average positron lifetime shows a pronounced increase within the first 10% and 40% of the fatigue life, respectively. In stress-controlled experiments the average positron lifetime at failure depends significantly on the applied stress amplitude. In strain-controlled experiments significantly different positron lifetimes for different applied plastic strain amplitudes are obtained within the first 1.000 fatigue cycles, whereas differences get wiped out during further cycling until failure.

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“…Due to their binding energy of E b Ͻ 100 meV dislocation are shallow positron traps. 2,[5][6][7][8] Dislocation lines are considered to act as precursor states for the transition into deeper traps, such as jogs 6,9 or vacancies, which are bound in the stress field around dislocations. 10,11 In moleculardynamics studies on Al the positron binding energy was calculated to be 1.0 eV for a vacancy elastically bound to a dislocation line and 1.3 eV for a dislocation with a jog.…”

Section: Introductionmentioning

confidence: 99%

Correlation of mechanical stress and Doppler broadening of the positron annihilation line in Al and Al alloys

Hugenschmidt

Stadlbauer

et al. 2009

Phys. Rev. B

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The plastic deformation of Al samples, of the technical alloys AlMgSi0.5, and AlMg3 was studied by Doppler-broadening spectroscopy ͑DBS͒ of the positron annihilation line. First, the defect sensitive line-shape parameter S was measured after the application of axial tensile stress, and the corresponding stress-strain curves were recorded that allowed us to correlate the strain, the mechanical stress and the S-parameter values after mechanical load quantitatively. In a next step, asymmetrically deformed Al samples were investigated with a monoenergetic positron beam by DBS in order to obtain the laterally resolved information of the stress-induced defects. It is demonstrated that the resulting two-dimensional S-parameter map ͑scan area 14ϫ 14 mm 2 , step width 1 mm͒ can be expressed quantitatively in terms of the locally acting stress which is responsible for the creation of the lattice defects.

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Temperature Dependence of Positron Trapping to Dislocations in Deformed Zinc

Cited by 8 publications

References 5 publications

Predicting the Lifetime of Steel

Predicting the Lifetime of Steel

Nondestructive monitoring of fatigue damage evolution in austenitic stainless steel by positron-lifetime measurements

Correlation of mechanical stress and Doppler broadening of the positron annihilation line in Al and Al alloys

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