Temperature studies using positron lifetime spectroscopy of the subsurface zone in pure titanium exposed to a dry sliding test

2021 ◽  
pp. 135065012110605
Author(s):  
Jerzy Dryzek
Keyword(s):  
Positron Lifetime ◽  
Pure Titanium ◽  
Dry Sliding ◽  
Vacancy Clusters ◽  
Long Period ◽  
Subsurface Zone ◽  
Long Duration ◽  
Different Depths ◽  
Positron Lifetime Spectroscopy ◽  
Sliding Test

The report presents the positron annihilation studies of subsurface zone generated in pure titanium exposed to a long period dry sliding test. The total depth of the subsurface zone induced is detected at about 250 µm. Only dislocations and vacancy clusters which consist of two or three vacancies are observed in this zone. Their concentration decreases with the depth, especially at the depth above 100 µm. Despite the long duration of the sliding test, no clear signs indicating the presence of a tribolayer were observed. This was confirmed also by observation of annealing of defects in this zone at different depths. The lack of the tribolayer is in contrast to the research done so far for other metals.

Strain-Rate Dependence of Vacancy Cluster Size in Hydrogen-Charged Martensitic Steel AISI410 under Tensile Deformation

2017 ◽  
Vol 373 ◽  
pp. 171-175 ◽  
Author(s):  
Kazuki Sugita ◽  
Yasumasa Mutou ◽  
Yasuharu Shirai
Keyword(s):  
Strain Rate ◽  
Positron Lifetime ◽  
Tensile Deformation ◽  
Martensitic Steel ◽  
Vacancy Cluster ◽  
Rate Dependence ◽  
Strain Rate Dependence ◽  
Strain Rates ◽  
Vacancy Clusters ◽  
Positron Lifetime Spectroscopy

The strain-rate dependence of vacancy cluster sizes in hydrogen-charged martensitic steel AISI410 under tensile deformation was investigated using positron lifetime spectroscopy. The vacancy-cluster sizes in hydrogen-charged samples tended to increase with decreasing strain rates during the tensile deformations. The vacancy-cluster sizes significantly correlated to the tensile elongations to fracture. It was revealed that the presence of large-sized vacancy-clusters can cause the degradation of mechanical properties and followed by brittle fracture.

Subsurface Zone in Pure Magnesium Studied by Positron Lifetime Spectroscopy

2005 ◽  
Vol 20 (1) ◽  
pp. 91-97 ◽  
Author(s):  
J. Dryzek ◽  
E. Dryzek ◽  
T. Suzuki ◽  
R. Yu
Keyword(s):  
Positron Lifetime ◽  
Pure Magnesium ◽  
Subsurface Zone ◽  
Positron Lifetime Spectroscopy

Deformation-induced vacancy-type defects in GaAs

1991 ◽  
Vol 69 (3-4) ◽  
pp. 298-306 ◽  
Author(s):  
P. Mascher ◽  
S. Dannefaer ◽  
D. Kerr
Keyword(s):  
Isothermal Annealing ◽  
Positron Lifetime ◽  
Total Concentration ◽  
Vacancy Cluster ◽  
Void Size ◽  
Shallow Trap ◽  
Vacancy Clusters ◽  
Positron Lifetime Spectroscopy ◽  
Average Size ◽  
Shallow Traps

Semi-insulating undoped GaAs was plastically deformed and then investigated by positron-lifetime spectroscopy. Strains between 0 and 40% and temperatures of deformation of 450, 500, and 600 °C were investigated, with detailed investigations carried out for the lowest temperature of deformation. Between 0 and 4% strain, a reduction of the grown-in vacancy response takes place simultaneously with a slight increase in vacancy cluster size to two or three vacancies. Between 4 and 6% strain a very substantial increase in vacancy production occurs but nearly all of these vacancies are clustered into voids with a radius of about 50 Å (1 Å = 10−10 m) and density in the order of 1013–1014 cm−3. The total concentration of vacancies necessary to produce these voids is 1017–1018 cm−3. This clearly shows that vacancies are formed upon deformation and that they are mobile at 450 °C. Upon further deformation to 20% strain, the overall defect concentration becomes so high that all positrons become trapped for which reason no absolute defect concentrations can be deduced. The dominant defect types can nevertheless be identified as voids (of average size of 20 Å), two- or three-vacancy clusters, and shallow traps. Isothermal annealing of 40% strained samples shows that heat treatment reduces the void concentration but increases the average void size, and results only in a small decrease in shallow-trap concentration. The shallow traps are likely the dislocation lines themselves and the small vacancy clusters appear to be associated with the dislocation lines.

A Study of Defects in Czochralski-Grown Silicon by Positron Annihilation Spectroscopy

1992 ◽  
Vol 262 ◽  
Author(s):  
S. C. Sharma ◽  
N. Hozhabri ◽  
R. G. Hyer ◽  
T. Hossain ◽  
S. Kim ◽  
...  
Keyword(s):  
Positron Lifetime ◽  
Single Crystal Silicon ◽  
Positron Beam ◽  
Positron Annihilation Spectroscopy ◽  
Doppler Broadening ◽  
Crystal Silicon ◽  
Different Depths ◽  
Positron Lifetime Spectroscopy ◽  
Doppler Broadening Spectra ◽  
Variable Energy

ABSTRACTWe have studied defects in Cz-grown single crystal silicon by utilizing a variable energy positron beam and positron lifetime spectroscopy in conjunction with surface photovoltage measurements. We present results for the depth profile of defects obtained from the Doppler broadening spectra measured by implanting variable energy positrons at different depths ranging from the surface down to ∼ 1 /xm deep. We have also measured positron lifetime spectra at different locations on a wafer and have obtained a radial variation in the density of the vacancy-type defects.

Positron Annihilation Spectroscopy of Defects in Commercially Pure Titanium Saturated with Hydrogen

2014 ◽  
Vol 880 ◽  
pp. 134-140 ◽  
Author(s):  
Roman S. Laptev ◽  
Yuriy S. Bordulev ◽  
Viktor N. Kudiiarov ◽  
Andrey M. Lider ◽  
Georgy V. Garanin
Keyword(s):  
Gas Phase ◽  
Positron Lifetime ◽  
Pure Titanium ◽  
Metal Structure ◽  
Positron Annihilation Spectroscopy ◽  
Doppler Broadening ◽  
Commercially Pure Titanium ◽  
Commercially Pure ◽  
Hydrogen Interaction ◽  
Positron Lifetime Spectroscopy

The experimental study of the structure of commercially pure titanium after saturation with hydrogen from the gas phase by means of positron lifetime spectroscopy (PLS) and Doppler broadening spectroscopy (DBS) was carried out. In the result of penetration and accumulation of hydrogen, significant changes of annihilation characteristics occurred due to the defect structure changing. The investigated samples contained hydrogen in concentrations varying from 0 to 0.961 wt.%. Several stages of hydrogen interaction with the metal structure were revealed.

Observation of Vacancy Clusters in HTCVD Grown SiC

2005 ◽  
Vol 483-485 ◽  
pp. 469-472 ◽  
Author(s):  
Reino Aavikko ◽  
Kimmo Saarinen ◽  
Björn Magnusson ◽  
Erik Janzén
Keyword(s):  
Silicon Carbide ◽  
Chemical Vapor Deposition ◽  
High Temperature ◽  
Vapor Deposition ◽  
Positron Lifetime ◽  
Chemical Vapor ◽  
Vacancy Clusters ◽  
Positron Lifetime Spectroscopy

Positron lifetime spectroscopy was used to study defects in semi-insulating (SI) silicon carbide (SiC) substrates grown by high-temperature chemical vapor deposition (HTCVD). The measured positron lifetime spectra can be decomposed into two components, of which the longer corresponds to vacancy clusters. We have carried out atomic superposition calculations to estimate the size of these clusters.

Microstructure and Defects of MgO/ZrO2 Nanocrystals Investigated by Positron Annihilation Spectroscopy

2017 ◽  
Vol 373 ◽  
pp. 249-253
Author(s):  
Jia Heng Wang ◽  
Jian Jian Shi ◽  
Wei Yang ◽  
Zhe Jie Zhu ◽  
Yi Chu Wu
Keyword(s):  
Single Phase ◽  
Annealing Temperature ◽  
Positron Lifetime ◽  
Positron Annihilation Spectroscopy ◽  
X Ray Diffraction ◽  
Mgo Nanoparticles ◽  
Vacancy Defects ◽  
X Ray ◽  
Vacancy Clusters ◽  
Positron Lifetime Spectroscopy

Pure MgO, ZrO2 and mixture MgO/ZrO2 nanocrystals were annealed in air from 100 to 1200°C. Variation of the microstructure and defects was investigated by positron lifetime spectroscopy and X-ray diffraction. The experiment results showed that the average positron lifetime of mixture MgO/ZrO2 was more larger than that of single phase MgO and ZrO2, and decreased with the increasing annealing temperature. Thermal annealing below 600°C, the movement of grain boundaries mainly led a reduce of the number of microvoids, and vacancy defects began to recover due to the growth of MgO nanoparticles after annealing between 600 to 900°C. Furthermore, ZrO2 nanoparticles began to grow above 900°C, meanwhile the recovery of vacancy and vacancy clusters in MgO/ZrO2 nanoparticles are restrained because of synergic effect between MgO and ZrO2 nanoparticles.

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