Studies of Radiation Embrittlement of Model Alloys by Thermoelectric Measurements and Positron Annihilation Spectroscopy
نویسندگان
چکیده
One of the basic mechanisms of radiation embrittlement of steels and welds is due to matrix damage. Embrittlement results in a raise in the ductile-to-brittle transition temperature, which is normally used as indicator of the degradation status of the material. Other methods different than mechanical tests can be used to follow embrittlement like small punch test, non-destructive measurements of thermo-electric and magnetic properties, positron annihilation spectroscopy (PAS) measurements, etc. As regards assessment of reactor pressure vessel’s radiation embrittlement, a need exists for correlation not only between the microstructural changes and the non-destructive techniques (NDT) results, but also between the non-destructive evaluation (NDE) outcomes and the mechanical behaviour or level of embrittlement. At the JRC-IE the measurement of thermoelectric voltage using a specially developed nondestructive method (STEAM) to assess the embrittlement state of materials is regularly performed. The positron annihilation spectroscopy in lifetime setup (PAS-LT) is used for study the microstructural changes of matrix due to embrittlement process. Both techniques, STEAM and PAS, have been applied to test a number of complex model alloys with different chemical composition, and several irradiation conditions. The obtained results prove that both techniques are good indicators of the change in material properties, given that their main parameter increases by effect of radiation dose like it occurs with the ductile-to-brittle transition temperature. Furthermore the combination of thermoelectric “STEAM” and PAS measurements seems to be promising for investigation of irradiation degradation mechanisms.
منابع مشابه
Positron annihilation lifetime spectroscopy in nickel ferrite and iron oxide nanopowders
In this study, a positron annihilation lifetime spectrometer was set up and its resolution was optimized. The spectrometer is a fast-slow arrangement with time resolution of 250 ps. To obtain lifetime components and their intensities from analyzing positron annihilation lifetime spectrum, the Pascual software is used. Positrons are from a source of radioactive 22NaCl with 20 μCi activity enclos...
متن کاملTitanium-Rich Precipitate Evolution in Vanadium-based Alloys Studied by TEM and Positron Annihilation Spectroscopy
متن کامل
Aging behavior in Cu–Al–Be shape memory alloy
This article reports positron annihilation spectroscopy and calorimetric measurements of the aging behavior in a Cu–Al–Be shape memory alloy. An excess of single vacancies is retained in the alloy as a result of a quench. All vacancies in excess disappear after long aging time, and a migration energy EM51.060.1 eV for this process has been found to be larger than in other Cu-based shape memory ...
متن کاملPositron Annihilation Measurements on Nuclear Reactor Pressure Vessel Steels
Positron Annihilation Spectroscopy is a valuable microscopic method to study radiation damage in nuclear reactor pressure vessel steels. At SCKoCEN, a new positron lifetime setup, suited to measure positron lifetimes in irradiated steel, is being constructed. The particularity of this setup is that the prompt count rate originating from the induced 60Co-activity in the steel is highly reduced. ...
متن کاملNew insights into the nanostructure of innovative thin film solar cells gained by positron annihilation spectroscopy
Recent studies showed that positron annihilation methods can provide key insights into the nanostructure and electronic structure of thin film solar cells. In this study, positron annihilation lifetime spectroscopy (PALS) is applied to investigate CdSe quantum dot (QD) light absorbing layers, providing evidence of positron trapping at the surfaces of the QDs. This enables one to monitor their s...
متن کامل