Effect of stress on radiation-induced hardening of A533B and Fe-Mn model alloys

In this study, a small tensile test machine was inserted in the beam line of a tandem-type accelerator. After 2.4 MeV Fe²⁺ ion irradiation, the microstructure and hardness changes of the specimens with and without applied stress were studied. Without stress, the formation of small interstitial-type dislocation loops was prominent in the matrix and also in the vicinity of dislocations in the Fe-1.4 wt.%Mn alloy. At room temperature, radiation-induced hardening was more prominent in samples with stress than in samples without stress. However, at 563 K, the effect of stress on hardness changes was minor. TEM observations showed that the applied stress reduced loop nucleation and enhanced loop growth to a degree corresponding to the microstructure at higher-temperature irradiation. This study revealed that the formation of interstitial-type dislocation loops enhanced by Mn addition was essential for irradiation hardening of these samples both with and without applied stress at higher dose levels.