Huai-Hsun Lien¹, Amit Misra¹, Jyoti Mazumder¹; ¹University of Michigan

Heterogeneous metallic materials with multimodal grain size distribution of constituent grains and phases show significant improvements in ductility at yield strength comparable to their nanocrystalline counterparts. In this report, model system heterogeneous hypereutectic Al-20Si with \\956m-size coarse Al dendrites embedded in nm-size ultrafine Al-Si eutectic was fabricated by laser surface remelting (LSR). The mechanical properties of both the heterogeneous Al-Si structure and fully ultrafine eutectic was studied. Hardness testing and micropillar compression reveal different mechanical properties for as-cast Al-12Si eutectic, heterogeneous structure and fully ultrafine eutect. In addition, the hardness increases as the fraction of ultrafine Al-Si eutectic increase. in-situ SEM and in-situ TEM further reveal the deformation behaviors of micropillars and nanopillars. These findings are crucial to constructing the microstructure to mechanical property map for future guidance.