True stress–strain data are obtained through the thermal compression test of cobalt‐based superalloy GH5188 at temperature range 1080–1180 °C and strain rate 0.1–10 s −1 , Arrhenius constitutive equation considering effects temperature, rate, is established. The microscopic deformation mechanism appropriate process proposed based on analysis dynamic material model electron backscattered diffraction (EBSD). results show that established exhibits predictive ability, calculated activation...

Structural models for dislocation, vacancy clusters, twin boundary, stacking fault and nanocrystalline sample are constructed using copper as a model material. Positron lifetimes momentum distributions of annihilating electron–positron pairs calculated these structural models. The results indicate that the boundary shallow traps to positrons. dislocation associated with monovacancies gives rise positron lifetime similar monovacancies. show no dependence on mean grain size. as-constructed...

Thermoelectric samples prepared by spark plasma sintering method have been studied resistivity measurement, X-ray diffraction (XRD) and positron annihilation spectroscopy (PAS). The existence of Zn vacancies in structure is confirmed PAS, which contribute a lifetime component ps. Positron calculation has performed for different defect structural models . By comparing the calculated values with experimental result, we find that each vacancy must at least two close interstitial atoms crystal...

Defects in as-grown undoped and tellurium-doped gallium antimonide were studied using positron lifetime coincidence Doppler broadening measurements. The grown-in defects these samples supposed to be Ga vacancy (VGa)-related defects. More VGa-related introduced into lightly Te-doped GaSb after electron irradiation at the doses of 1.0 × 1017 cm−2 1018 cm−2; however, heavily GaSb, led partial recovery VGa. role Te content defect evolution is also discussed.

An analysis program for positron annihilation lifetime spectra is only applicable to isolated defects, but of no use in the presence defective correlations. Such limitations have long caused problems researchers their studies complicated systems. In order solve this problem, we aim take a semiconductor material, example, achieve credible average single crystal silicon under plastic deformation at different temperatures using life time spectroscopy. By establishing reasonable trapping models...

Thermoelectric properties of pure, Cd- and In-doped ZnSb are studied by first principles calculations electronic structures the semi-classical Boltzmann transport theory. The doping Cd or In at Zn lattice site slightly increases parameters due to larger atomic radii compared with that Zn. also apparently interatomic distances between dopant atoms surrounding atoms. power factor n-type is much than p-type ZnSb, indicating has better thermoelectric performance ZnSb. After In, reduces mainly...

Microstructure of unfilled and Ba-filled CoSb3 has been studied by positron lifetime measurements together with theoretical calculation. Positron trapping in intrinsic voids is observed the CoSb3, which contributes a 263 ± 2 ps. After filling Ba atoms content up to x = 0.4, shows continuous increase. By comparing experimental results calculation following phase diagram BaxCo4Sb12 range 0–0.5, it found that when lower than 0.16, solid solution. At 0.2, γ formed, mixed > 0.25,...

Thermal stability of nanocrystalline Cu prepared by compacting nanoparticles (mean grain size about 50 nm) under high pressure has been studied means positron annihilation lifetime spectroscopy and X-ray diffraction. A gradual increase mean in the sample is observed with an ageing time at 180°C, indicating volume fraction ordered regions. Furthermore, during ageing, average vacancy clusters boundaries confirmed results. The recrystallization temperature becomes significant above 650°C. Three...

The plastic deformation of nanocrystalline Zn is investigated by positron annihilation lifetime spectroscopy. carried out exerting a pressure on the surface samples, which causes thickness reduction samples. different behavior relative with increasing between sample and conventional bulk indicates that distinct mechanism operating in sample. results confirm indirectly grain boundary based, such as sliding. Once annealed at high temperature, changes become similar to those Furthermore,...

Defects in phosphorus-doped float-zone silicon single crystals plastically deformed at 800 °C were studied by the positron lifetime technique. The measurements performed for undeformed, as-deformed and all annealed samples temperatures varying from 20 K to 300 K. Three kinds of defects including vacancy clusters, dislocation-bound vacancies undisturbed dislocations are induced deformation. It is proposed that dislocation could be charged this was well proved fitting experimental with...

Nanocrystalline copper and zinc prepared by high-pressure compaction method have been studied positron lifetime spectroscopy associated with X-ray diffraction. For nanocrystalline Cu, mean grain sizes of the samples decrease after being annealed at 900 °C increase during aging 180 °C, revealing that atoms exchange between two regions. The results indicate vacancy clusters formed in annealing process are unstable decomposed time below 6 hours. In addition, partially oxidized surfaces...

Abstract Biaxial strain effects on the electronic structure and thermoelectric properties of Pnma phase SnSe are investigated by first-principles calculations Boltzmann transport theory. The biaxial strains ε ab , ac bc were applied ab, planes from −6% to 6%, respectively. band gap decreases under compressive strains, increases tensile except for = 6%. can tune in a large range 0 eV 0.88 eV. A semiconductor metal transition is observed at < −4%. also influence with phase. momentum...