Mechanical properties and corrosion behavior of hetero-structured lean Mg-1Bi-0.5Sn-0.5In alloy
(1. School of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, China;
2. The Open Project of Salt Lake Chemical Engineering Research Complex, Qinghai University, Xining 810016, China;
3. School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300132, China;
4. School of Materials Science and Engineering, North University of China, Taiyuan 030051, China;
5. Magnesium Technology Innovation Center, Department of Materials Science and Engineering, Seoul National University, Seoul-08826, Korea)
2. The Open Project of Salt Lake Chemical Engineering Research Complex, Qinghai University, Xining 810016, China;
3. School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300132, China;
4. School of Materials Science and Engineering, North University of China, Taiyuan 030051, China;
5. Magnesium Technology Innovation Center, Department of Materials Science and Engineering, Seoul National University, Seoul-08826, Korea)
Abstract: The microstructural characterization, corrosion behavior and tensile properties of the extruded lean Mg-1Bi-0.5Sn-0.5In (wt.%) alloy were investigated through scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), X-ray photoelectron spectroscopy (XPS), electrochemical measurements and tensile tests. The results reveal that a microstructure consisting of dynamically recrystallized and deformed grains is obtained. Notably, the investigated alloy exhibits excellent strength-ductility synergy, with tensile yield strength (TYS), ultimate tensile strength (UTS) and elongation (EL) of 254.8 MPa, 315.4 MPa, and 25.3%, respectively. Furthermore, in 3.5 wt.% NaCl solution, with the increase of immersion time, the dominant corrosion mechanism of the studied alloy transforms from pitting corrosion to filiform corrosion. After the immersion for 24 h, a composite oxide film (SnO2- Bi2O3-In2O3) is formed, which delays the corrosion process, and the corrosion rate (PH=1.53 mm/a) is finally stabilized.
Key words: Mg alloy; extrusion; corrosion behavior; tensile properties; strengthening mechanism