Heat resistant magnesium alloy

Abstract

A magnesium alloy includes 0.1 to 6.0% by weight of Al, 1.0 to 6.0% by weight of Zn, 0.1 to 3.0% by weight of rare earth element (hereinafter referred to as 'R.E.'), and balance of Mg and inevitable impurities. By thusly adding Al and Zn, the castability, especially the die-castability, is improved. At the same time, the room temperature strength can be improved because the Mg-Al-Zn crystals having a reduced brittleness are dispersed uniformly in the crystal grains. Further, by adding R.E. as aforementioned, the high temperature strength is improved because the Mg-Al-Zn-R.E. crystals having a higher melting point and being less likely to melt are present in the crystal grain boundaries between the Mg-Al-Zn crystals. This magnesium alloy is excellent in castability, can be die-cast, has a higher tensile strength at room temperature, and is satisfactory in high temperature properties and creep properties. Moreover, when the magnesium alloy includes R.E. in a reduced amount of 0.1 to 2.0% by weight, and further includes 0.1 to 2.0% by weight of Zr and 0.1 to 3.0% by weight of Si, it becomes a magnesium alloy, which is further excellent in the castability, which has a higher tensile strength at room temperature, which is further superb in the high temperature properties and the creep properties, and at the same time whose corrosion resistance is upgraded.