Effect of undersized solute atoms on point defect behavior in V–A (A=Fe, Cr and Si) binary alloys studied by using HVEM

Point defect behavior in pure vanadium and V–A binary alloys, which contain undersized solute atoms, are examined by using high voltage electron microscope. In alloys, the number densities of self-interstitial (SIA) loops are found to be much higher than that in vanadium, indicating that solute atoms trap SIAs and enhance loop nucleation. Moreover, in contrast to the case of pure vanadium, several stages are observed in the Arrhenius-type plot of the loop density. From the temperature dependence of the loop density in each alloy, the activation energies of 0.81, 0.65 and 0.99 eV for V–xFe (x⩾0.1 at.%), V–yCr (y⩾1 at.%) and V–1Si have been obtained, respectively. Complex loop shapes have been observed in all alloys. Those become more significantly with increasing solute concentration, indicating solute segregation to loops. Various observed phenomena are discussed in terms of the obtained activation energy.