Mechanical Properties of a Flame-resistant Mg Alloy as a Next-generation Transportation Structural Material

Mg alloys could potentially be used as the structural materials of next-generation high-speed transportation systems on account of their extremely low density (1.7 Mg/m3). However, the plastic formability of Mg alloys at room temperature is poor, which can be attributed to the hexagonal close-packed (hcp) crystal structure. Moreover, Mg alloys are flammable as a result of the activated metal in the alloy. In this study, we investigate the microstructure and mechanical properties of a flame-retardant Mg alloy that contains Ca in order to improve the ignition of such alloys. In particular, the addition of Ca results in an oxide film and raises the ignition temperature from ∼300 to 400 K. The average grain size of the alloy used in this study is 16 μm. From the results of various tensile tests, which were conducted for the directions parallel to, perpendicular to, and at 45˚ to the extrusion direction (ED), the anisotropy of the mechanical properties associated with the tensile direction is confirmed. More specifically, the anisotropy of the mechanical properties of this alloy is discussed in relation to the alloy's microstructural features.