高温プレスを利用した加工熱処理によるMg-9Al-1Zn-2Ca合金板の機械的特性向上

Abstract

Flame-retardant magnesium alloys prepared by adding calcium have been used as lightweight structural material. Thermomechanical treatments using hot rolling or hot extrusion are effective to improve the mechanical properties of flame-retardant magnesium alloys. This study focuses on the uniaxial hot pressing process for improving the mechanical properties of cast Mg-9Al-1Zn-2Ca alloy. The hot pressing tests were carried out with different temperatures up to 673 K and maximum compression strains of 65％. Microstructural characterization was carried out using a field-emission scanning electron microscope equipped with an electron back scattered diffraction system. 0.2％ proof stress, tensile strength and elongation to fracture were measured by a universal testing machine at room temperature. The Mg-9Al-1Zn-2Ca alloy showed the highest strength after the 65％ compression at 573 K, and the highest ductility after the 65％ compression at 673 K. The enhanced mechanical properties are attributed to grain refinement caused by dynamic recrystallization and reduced cavities due to the high compression strain.