Phase interface induced stacking faults in Al-7.5Y alloy revealed by in-situ synchrotron X-ray diffraction and ex-situ electron microscopy

Stacking faults (SFs) were found at the matrix/reinforcement interface in aluminum (Al) composites in spite of the high stacking fault energy (SFE) of Al. This paper is a contribution into understanding of the relationship between phase interfaces and SFs formation. The role of phase interface on the formation of SFs in Al-7.5wt.%Y eutectic alloy was studied using in-situ synchrotron X-ray diffraction and ex-situ electron microscopy. The experimental findings reveal two-stages of plastic deformation behavior of the material. At the early stage, the plastic deformation is dominated by dislocation glide. At the later stage, SFs arise, in addition to dislocation glide. It is rationalized here that the interfacial stress built at the Al/Al3Y interface triggers the formation of SFs in Al by decreasing the effective stacking fault energy.