The composition dependence of the effective vacancy formation enthalpy in copper-rich brass as deduced from the threshold temperature for positron trapping in vacancies

1978 ◽  
Vol 56 (8) ◽  
pp. 1077-1083 ◽  
Author(s):  
P. J. Schultz ◽  
T. E. Jackman ◽  
J. Fabian ◽  
E. A. Williams ◽  
J. R. MacDonald ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Positron Annihilation ◽  
Composition Dependence ◽  
Formation Enthalpy ◽  
Vacancy Formation ◽  
Threshold Temperature ◽  
Α Phase ◽  
Linear Decrease ◽  
Zn Concentration ◽  
Bcc Structure

The temperature dependence of the Doppler-broadened positron annihilation lineshape has been measured for 13 brass specimens with compositions varying from 0 to 48% by weight of Zn. The vacancy formation enthalpy deduced from these measurements shows a linear decrease of 22% with increasing Zn concentration through the α phase and a further 31% decrease on changing from fcc to bcc structure.

Measurements of the vacancy formation enthalpy in aluminum using positron annihilation spectroscopy

1978 ◽  
Vol 17 (9) ◽  
pp. 3444-3455 ◽  
Author(s):  
M. J. Fluss ◽  
L. C. Smedskjaer ◽  
M. K. Chason ◽  
D. G. Legnini ◽  
R. W. Siegel
Keyword(s):  
Positron Annihilation ◽  
Formation Enthalpy ◽  
Positron Annihilation Spectroscopy ◽  
Vacancy Formation

Vacancy formation energies in bcc and fcc stainless steels by positron annihilation

1983 ◽  
Vol 61 (1) ◽  
pp. 140-145 ◽  
Author(s):  
S. M. Kim ◽  
W. J. L. Buyers
Keyword(s):  
Temperature Dependence ◽  
Positron Annihilation ◽  
Stainless Steels ◽  
Theoretical Models ◽  
Model Analysis ◽  
Vacancy Formation ◽  
Coincidence Rate ◽  
Annihilation Peak ◽  
Trapping Model ◽  
Formation Energies

The temperature dependence of the positron annihilation peak coincidence rate has been measured in bcc and fcc stainless steels. Trapping model analysis of the data shows that the vacancy formation energies in the bcc stainless steels are about 20% lower than those in the fcc stainless steels. The vacancy formation energies calculated from current theoretical models are about 10–15% larger than those determined experimentally.

The vacancy formation enthalpy in Ni determined by positron annihilation

1981 ◽  
Vol 11 (11) ◽  
pp. 2221-2230 ◽  
Author(s):  
L C Smedskjaer ◽  
M J Fluss ◽  
D G Legnini ◽  
M K Chason ◽  
R W Siegel
Keyword(s):  
Positron Annihilation ◽  
Formation Enthalpy ◽  
Vacancy Formation

Positron Annihilation Studies of Vacancy Formation in Tungsten, Chromium, and Niobium

1984 ◽  
Vol 41 ◽  
Author(s):  
L. C. Smedskjaer ◽  
G. D. Loper ◽  
M. K. Chason ◽  
R. W. Siegel
Keyword(s):  
Positron Annihilation ◽  
High Vacuum ◽  
Formation Enthalpy ◽  
Positron Annihilation Spectroscopy ◽  
Ultra High Vacuum ◽  
Vacancy Formation ◽  
Self Diffusion ◽  
Melting Temperatures ◽  
Bcc Metals ◽  
Diffusion Studies

AbstractVacancy formation was studied in the refractory bcc metals, tungsten, chromium, and niobium, using the positron annihilation spectroscopy Doppler broadening technique, between room temperature and the respective melting temperatures, under ultra-high vacuum conditions. Temperatures were measured by optical and infrared pyrometry, a W(Rh) thermocouple, and the power delivered to the sample, with calibrations against known melting temperatures. For W, a trapping-model analysis of the data from the temperature range 300–3633 K yielded a vacancy formation enthalpy of 3.76 ± 0.39 eV. For Cr, a similar fit to the data from 296–2049 K yielded a vacancy formation enthalpy of 2.0 ± 0.2 eV. The results are discussed in relation to previous vacancy formation and self-diffusion studies. Measurements on Nb as a function of temperature and oxygen content are also presented.

THE TEMPERATURE DEPENDENCE OF VACANCY GIBBS FORMATION ENERGY FOR α-ZIRCONIUM

2012 ◽  
Vol 26 (28) ◽  
pp. 1250185
Author(s):  
ELIZABETH DOLOGLOU
Keyword(s):  
Gibbs Energy ◽  
Temperature Dependence ◽  
Point Defect ◽  
Thermodynamic Model ◽  
Formation Energy ◽  
Formation Enthalpy ◽  
Vacancy Formation ◽  
Elastic Data ◽  
Expansivity Data

In this paper, we show that by using a thermodynamic model which interconnects point defect parameters with bulk elastic and expansivity data, we successfully estimate the temperature dependence of the Gibbs energy for vacancy formation in α-zirconium. Based on the recent elastic data, the model leads to the values of the ratio of the formation entropy over formation enthalpy, at various temperatures, that compare well with reported ones.

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