Track formation in indium phosphide under irradiation by swift heavy ions

In the framework of this paper we carried out a numerical simulation of an evolution of the temperature fields that arise along the trajectories of swift heavy ions ({E/M} ~ units of MeV/a.m.u.) in indium phosphide with regard for energy dissipation and variation of the charge state of stopping ions over the depth. Thermal spike model was used as a physical basis for calculations. The simulation results on spatial parameters of being formed tracks are in good agreement with existing experimental data. Charge state fluctuations mechanism is discussed as being responsible for discontinuous track formation

Role of dislocation loops in the development of vacancy voids

This paper presents the results of a transmission electron microscopy (TEM)-investigation of the effect of post-irradiation innealing on the structure of molybdenum and nickel doped with helium atoms that was irradiated with high-energy a-particles and fission neutrons. It is shown that: • The number of interstitial atoms in dislocation loops and the number of vacancies in helium bubbles increase as annealing temperature and time increase. • The growth of helium bubbles on the grain boundary is mainly observed on the side of the grain body where there are dislocation loops. • Post-irradiation annealing of dislocation loops fonmed by SO-MeV a-particles and fission neutrons at 60°C results in the growth of vacancy voids. Thus, high temperature post-irradiation annealing or irradiation at high temperature (more than 0.3Tme«) constitutes the conditions under which dislocation loops are powerful sources of vacancies. Consequently, if in the crystal structure of the irradiated material there are HemVn groups, vacancy oversaturation caused by the thermal emission of vacancies by radiationinduced dislocation loops may be the main driving force for the nucleation and growth of vacancy voids

Helium effect on phase structural changes in carbon steel under post-irradiation phase recrystallization

In the present paper a new radiation effect related to thermally irreversible structural changes during post-irradiation phase transformation in a-particle irradiated region of the sample of the U7 steel [0.77; carbon) is demonstrated. The samples of the U7 carbon steel have been irradiated at the cyclotron with a-particles with energies of 29 and 50 MeV up to dose 1.5x10 cm"^ and with protons with energy of 10 MeV up to dose 2.5x10" cm'^ at temperatures not more than 100° С The results of metallography study of as-irradiated, annealed and carburized after full decarburisation samples allow to establish two important facts. First, the irradiation of the U7 carbon steel with high-energy protons and alpha-particles which results in formation of radiation defects and hydrogen doping leaves any structural changes invariant in the process of post-irradiation annealing at temperatures 400-1100°C. Second, due to post-irradiation annealing in the range of temperatures above the а-7-transition tennperature in the helium doped sample regions of the U7 steel observes thermal irreversible structural changes (perhaps phase changes too): the formation of fine-grained ferrite-pearlite structure with an essential superiority of ferrite phase portion. It might be assumed that the main reason of the observed effect: is thermally stable complexes of helium atoms and vacancies in the form of helium bubbles rather than radiation defects