W0401(2) 急冷プロセスによる微細構造を有するマグネシウム粉末合金の組織と力学特性([W0401]粉末成形加工の新展開,ワークショップ)

Abstract

Rapidly solidified non-combustive magnesium alloy (AMX602; Mg-6Al-0.5Mn-2Ca/mass%) powders were prepared by SWAP method, one of the water-atomization processes. They revealed very fine α-Mg grains less than 500nm, and contained Al_2Ca and Al-Mn intermetallic compounds having a mean particle size of 100〜300 nm. Their magnesium alloy powders were consolidated by cold compaction, and served to hot extrusion after heating at 573K〜673K in argon gas atmosphere. AMX602 cast ingot was also applied to hot extrusion. Furthermore, the machined chips from the cast ingot were compacted at room temperature, and consolidated into a full density by hot extrusion. The dependence of microstructural and mechanical responses on the fabrication process conditions, such as raw materials and extrusion temperatures, was evaluated. The extruded AMX602 alloys using rapidly solidified powders indicated yield stress of 351MPa and elongation of 13.5%, which were superior to the wrought alloys using cast ingot materials. The extremely high strength was due to the α-Mg grain refinement less than 0.8μm of the extruded alloys. Such fine microstructures caused grain boundary sliding, and resulted in a good elongation to failure.