Tailoring AZ91 laminates for combination of strength and ductility
(1. State Key Laboratory of Mechanical Transmission, College of Materials Science and Engineering, Chongqing University, Chongqing 400044, China;
2. National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044, China)
2. National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044, China)
Abstract: Three types of laminates were designed by alternately stacking AZ91 extruded sheets in different states for extrusion to improve the mechanical properties. The tensile tests revealed that the combination of solid-solution-treated sheets with the aging-treated sheets achieved high tensile strength and ductility, i.e., ultimate tensile strength of ~386 MPa and elongation of ~19.8%, respectively. Electron backscatter diffraction (EBSD) and TEM results indicated that the aging-treated layers with more nano-sized precipitates and small grain size provided high strength and reasonable ductility, while the solid-solution-treated layers with low dislocation density facilitated strain hardening. Also, the strong interface bonding between the successive layers played an important role in the enhanced ductility.
Key words: AZ91 Mg alloy; solid solution treatment; aging; extrusion; mechanical properties