Studies of radiation embrittlement of model alloys by positron annihilation, thermo-electric and magnetic measurements

The most important effect of the degradation by radiation in steels and welds is the decrease in their ductility. The main ways to determine the mechanical behaviour of such steels are tensile and Charpy impact tests, from which the ductile to brittle transition temperature and its increase due to neutron irradiation can be calculated. These tests are destructive and regularly applied to assess the integrity of structural materials. The possibility of applying validated non-destructive monitoring techniques would however facilitate the surveillance of such materials. In this paper, the positron annihilation line-shape analysis performed on a limited number of complex model alloys with different chemical composition is presented. The results are compared with the values previously obtained by thermo-electric and magnetic Barkhausen measurements and with the results of Charpy impact destructive testing. The obtained results prove that positron annihilation is a good indicator of the change in material properties, given that its main parameter increases by effect of radiation as it occurs with the ductile to brittle transition temperature, and the magnetic and thermoelectric properties.