Effect of applied stress on radiation-induced loop and raft formation in molybdenum

Historically, different competing mechanisms have been proposed to explain the influence of applied stress on the formation and evolution of radiation-induced microstructures under irradiation. The active mechanism in cascade-producing environments, like ion or neutron irradiation, remains uncertain. This study presents direct evidence through in situ transmission electron microscopy (TEM) observations confirming the stress-induced preferential nucleation mechanism in body-centered cubic (BCC) pure molybdenum for cascade-producing particles. In this study, under external stress, radiation-induced loops mainly agglomerate into rafts along the {111} plane experiencing the highest applied stress while the average loop size is not affected by the external applied stress.