In-situ EBSD study of deformation behavior of Al–Si–Cu alloys during tensile testing

• EBSD maps of Al–Si–Cu alloy samples are distorted with increasing tensile strain.
• Higher SDAS specimen shows larger increase in the fraction of LABs than lower SDAS.
• Fe-rich needles and Si particles act as stress raisers resulting in strain localization.
• Higher SDAS specimen shows reduced mechanical properties due to strain inhomogeneity.

This study deals with the microstructural aspects of the deformation behavior in Al–Si–Cu alloy A380. This has been carried out with in-situ tensile testing coupled with EBSD analysis. The alloy specimens having different microstructures with two different secondary dendrite arm spacing (SDAS) of 9 μm and 27 μm were produced by the unique gradient solidification method. The study of misorientation distribution and texture evolution was performed with different tools in EBSD analysis. The texture was not significantly affected by deformation in both types of alloy specimens. With increase in the deformation, the microstructures are characterized by degradation of EBSD patterns and generation of substructures including low angle boundaries (LABs) and high angle boundaries (HABs). In both the microstructures with low and high SDAS, the boundaries were concentrated around eutectic phases; however this behavior was more pronounced at higher SDAS. The increase in the fraction of LABs with deformation was much higher in the microstructure with higher SDAS than with lower SDAS. This localized strain concentration was especially attributed to the large and elongated eutectic Si particles and Fe-rich intermetallics. The lower mechanical properties obtained at higher SDAS are the result of inhomogeneous strain distribution in the microstructure.

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