[en] The thermal release behavior of helium implanted into nickel with 20 keV He⁺ ions at fluences ranging from 1x10¹⁷ to 5x10¹⁷ ions/cm² has been studied. The number of helium release peaks increased and the temperature at which the release began became lower with increasing fluence. The surfaces of nickel samples heated after ion implantations were also examined. The release peaks were associated with distinct surface damage features such as holes and blisters. The release peak at high temperatures appeared to be controlled by the thermal vacancy absorption of bubbles. The release peaks at lower temperatures was attributable to the interbubble fracture associated with helium precipitation into bubbles. (orig.)