Fluence and flux dependence of void formation in pure aluminum

Neutron Irradiation Damage in a Precipitation-Hardened Aluminum Alloy.

“…n/om 2 causes 7.5$ swelling in high purity aluminum. 12 Silicon is generated in all of these materials but the major differences in swelling arise from differences in the total volume of voids. …”

Void nucleation and growth in heavy ion and electron bombarded pure metals. Progress report, March 1--December 1, 1974

“…We expect that we are close to the fluence threshold for void formation on the basis of work done by Packen. (25) 19 2 He'' found that no voids could be formed below 1.5 x 1 0 n/cm which is roughly 0.2 dpa using reported displacement cross section for Al. Since the majority of the present work was conducted at dpa levels of 0.26 to 0.68 dpa, the fluence argument appears to most plausible at the present time.…”

“…For helium concentrations much below that value, void nucleation in extremely pure metals (like the Al used in this study) is governed by homogeneous nucleation and that rate is obviously not high enough in the temperature-damage range of these studies to produce visable voids. It is interesting to note that Packen found a threshold for void formation at (25) 19 -2 -1 -3 1.5 x 10 n cm sec which corresponds to 6 x 10 appm helium ·…”

“…Analysis done at ORNL revealed 7 appm (29) solid impurities. Similar aluminum has been ubed in several neutronirradiated studies at ORNL , so comparison between neutron-irradiated (25)(26)(27) and ion-irradiated material can eventually be made.…”

“…While there has been a substantial number of studies on voids in neutron irradiated Al , there is only one other known study of high temperature heavy ion (25)(26)(27) bombardm ent of Al. Various workers have also examined the use of electron s (28) (29-32) \ on Al in attempts to produce voids,·but to date none have been successful.…”