Formation and migration of helium bubbles in Fe and Fe–9Cr ferritic alloy

Microstructural evolution in Fe and Fe–Cr model alloys after He+ ion irradiations

“…If the He-V cluster migration mentioned above is the appropriate mechanism, the experiments may indicate that a Cr addition decreases the mobility of He-V clusters. This was reported in the literature [10] in that the diffusivity of TEM-visible bubbles produced by He þ ion irradiation in Fe-9Cr is lower than that in Fe.…”

Release of helium from irradiation damage in Fe–9Cr ferritic alloy

“…For helium bubbles in the Fe9Cr alloy, Cr segregation on their surface has been revealed by present authors [13]. For dislocation loops formed by irradiation with He þ ions in Fe-9Cr, an elemental mapping of Fe and Cr across the loop is shown in Fig.…”

“…The segregated Cr around the dislocation loop or bubble could retard the motion of dislocations and bubbles and shift the related desorption spectra to higher temperatures. The retardation of the bubble mobility by segregated Cr in Fe-9Cr has been clarified by the present authors [13].…”

“…disappeared at the specimen surface and some coalesced. The motion profile and mobility of helium bubbles in Fe and Fe-9Cr have been reported by the present authors [13]. The phase transformation from a to c phase takes place around 1140 K and most bubbles were swept out following a movement of the phase boundary [14].…”

He bubble formation and emission of He in irradiated Fe

“…This was likely caused by absorption of single vacancies trapped by shallow trapping sites, such as Heinterstitial clusters, in the matrix. The long lifetime increased and its intensity decreased from 773 K. This indicated that small He bubbles were mobile at 773 K [9], which grew to be large with increasing annealing temperature to 1273 K, and subsequently shrank. He atoms were present even in He bubbles annealed at the high temperature of 1373 K. He atoms were emitted during annealing from 1273 to 1373 K according to the results of TDS.…”