Dissolution of gas-filled bubbles under heavy ions irradiation

Gas-filled bubbles present significant challenges in materials as they make materials porous and weaken the strength of materials. Here, argon bubbles that are formed during the fabrication of oxide dispersion strengthened (ODS) steels are investigated. The Ar bubbles are attached to nano-oxides which are dispersed in the matrix. MA956 ODS specimen was irradiated with 362 MeV 129Xe26+ at room temperature to about 7 dpa at peak damage. The behavior of Ar bubbles in different irradiation depths was investigated by using transmission electron microscopy (TEM) via cross-section specimens. The results show that Ar-bubbles in the peak damage and ions deposition region experience an apparent dissolution. Further, we simulate the behavior of isolated Ar bubble and attached Ar bubble to oxide under primary knock-on atoms (PKA) with different energy and numbers by using molecular dynamics (MD). The results show that high energy PKA (exceeding 30 keV) and multiple cascades can contribute to the effective ejection of Ar atoms from bubbles. Meanwhile, the interface between oxide and bubble contributes less to the bubble dissolution. Besides that, the effects of thermal ejection and excess self-interstitial atoms generated from the implantation of foreign atoms on the dissolution of Ar bubbles are discussed.