Abstract
The mechanism of radiation-induced detwinning is different from that of deformation detwinning as the former is dominated by supersaturated radiation-induced defects while the latter is usually triggered by global stress. In situ Kr ion irradiation was performed to study the detwinning mechanism of nanotwinned Cu films with various twin thicknesses. Two types of incoherent twin boundaries (ITBs), so-called fixed ITBs and free ITBs, are characterized based on their structural features, and the difference in their migration behavior is investigated. It is observed that detwinning during radiation is attributed to the frequent migration of free ITBs, while the migration of fixed ITBs is absent. Statistics shows that the migration distance of free ITBs is thickness and dose dependent. Potential migration mechanisms are discussed.
Highlights
The nanotwinned (NT) metals have attracted much attention as the twin boundaries (TBs) in NT metals underscore their unique combination of properties such as high strength, high ductility, excellent thermal stability, and retained electrical conductivity [1,2,3,4,5,6]
The mechanism of detwinning in terms of migration behavior of TBs in the nanotwinned Cu film was studied using in situ 1 MeV Kr2+ ion irradiation at room temperature
The results revealed that the migration of free incoherent twin boundaries (ITBs) is responsible for detwinning while fixed ITBs were stable during radiation
Summary
The nanotwinned (NT) metals have attracted much attention as the twin boundaries (TBs) in NT metals underscore their unique combination of properties such as high strength, high ductility, excellent thermal stability, and retained electrical conductivity [1,2,3,4,5,6]. The incoherent twin boundaries (ITBs) in NT metals are found to be unstable and easy to migrate during ion irradiation and deformation, especially when the twin thickness is smaller than 10 nm [5,8,13,14,15]. The first case is accomplished via the collective glide of Shockley partial dislocations at ITBs, and the migration of ITBs may lead to the detwinning of NT metals [16,17,18,19,20,21,22,23]. Several studies have revealed that detwinning during radiation is due to the migration of ITBs and the migration tendency is related to the stacking faults energy and twin thickness [8,13]. Discussions on the migration mechanisms might provide further understanding of the detwinning mechanism of NT metals during ion irradiation
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