The 1.85 GPa AlSc Bulk Alloy with Abundant Nanoscale Growth Twins
ZHUO Long-Chao1,2**, LIANG Shu-Hua1, ZHANG Tao3
1School of Materials Science and Engineering, Xi'an University of Technology, Xi'an 710048 2National Center for Electron Microscopy in Beijing, School of Materials Science and Engineering, State Key Laboratory of New Ceramics and Fine Processing, Laboratory of Advanced Materials, Tsinghua University, Beijing 100084 3Key Laboratory of Aerospace Materials and Performance (Ministry of Education), Department of Materials Science and Engineering, Beihang University, Beijing 100191
Abstract：An in situ ultrahigh-strength ductile Al50Sc50 bulk alloy is produced by the copper mold casting method with a composite microstructure of micron-/submicron-sized grains and nanoscale twins. According to the microstructural investigations, hierarchical nanotwinned lamellar AlSc bundles with embedded micron-/submicron-sized Al2Sc and AlSc2 are observed. The as-cast alloy displays a unique act of ultrahigh strength of ～1.85 GPa together with pronounced work hardening and a large plasticity of ～14%. Further microstructural investigations on deformed specimens indicate that abundant hierarchical nanotwinned lamellar AlSc bundles are effective to dissipate localization of shear stress or block dislocations from spreading throughout the alloy and hinder the propagation of microcracks formed by local stress transition.
2015, Vol. 32 
