Atomistic study of fundamental character and motion of dislocations in intermetallic Al₂Cu

Atomic scale study of the character and motion of dislocations in Al₂Cu will provide insights into understanding the superior mechanical properties of Al-Al₂Cu alloys. Using atomistic simulations, we studied seven potential slip systems (110)〈(001)〉, (010)〈(001)〉, (310)〈(001)〉, (010)〈(100)〉, (110)〈(110)〉, (110)〉12〈〈(111)〉 and (112)〉12(111)〉 in Al₂Cu with body centered tetragonal structure. We found that three edge dislocations with Burgers vector 〈(001)〉 on glide planes (110), (010), and (310), show an extended core and are predicted to be glissile at room and moderate temperatures. Other four edge dislocations associated with slip systems (010)〈(100)〉, (110)〈(110)〉, (110)〉12(111)〉 and (112)〉12(111)〉 and three screw dislocations with Burgers vectors 〈(001)〉, 〈(110)〉, and 〈12(111)〉 show a condensed core, and exhibit significantly higher Peierls barrier for glide at room temperature. Furthermore, the interaction of dislocation dipole associated with slip system (110)〈(001)〉 results in the climb of the extended-core dislocation at room temperature through three stages: the extended core condenses, the leading partial dislocation climbs accompanying the creation of vacancies (resulting in a non-planar core), and the two partials with non-planar core collectively glide on the neighboring slip planes associated with atomic shuffles.