Point defect interactions with Guinier-Preston zones in Al-Cu based alloys : Vacancy mediated GPZ to θ′-phase transformation

• The energetics of point defect interactions with a Guinier-Preston zone (GPZ) in Al alloys are systematically studied using ab initio calculations and a supercell approach. We find that vacancies can be trapped by GPZs and that the presence of a vacancy in a Cu layer qualitatively changes the solute–GPZ interactions. A vacancy mediated mechanism of GPZ to θ′-phase transformation is suggested and shown to be thermodynamically feasible, which involves the formation of structural vacancies and splitting of a GPZ layer into two half-vacant Cu layers. This mechanism, in combination with the calculated attractive solute-vacancy interactions, is predicted to result in the solute segregation at the interface between Al matrix and the forming θ′-phase precipitate.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Materialteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering (hsv//eng)

Nyckelord

Ab initio calculations

Aluminum alloys

Phase transformation

Point defects

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