Three-dimensional characterization of interaction between β″ precipitate and dislocation in Al–Mg–Si alloy

• 3D-ET was applied to investigate the interaction between precipitate and dislocation.
• Number density, intervals, critical angles were measured three-dimensionally.
• Macroscopic tensile test and yield stress by precipitates were compared directly.

Interaction between precipitates and dislocations is the most important factor governing mechanical properties of precipitation-hardening alloys. Thus large numbers of microstructural characterizations have been implemented to analyze this interaction by measuring critical angles and precipitate intervals. To date, these investigations have been performed using two-dimensional conventional transmission electron microscopy. In this study, a combination of transmission electron microscopy and computed tomography, three-dimensional electron tomography, was applied on balanced Al–Mg–Si alloy to measure critical angles and precipitate intervals and obtained 121° and 60 nm for β″ precipitates, respectively. The yield stress of precipitates measured by assigning these values, 150 MPa, was applicable to that measured from tensile test, 196 MPa.