초록 |
Among the various high-strength extruded Mg alloys developed to date, those with a high Al content such as AZ80 and AZ91 have been widely used in commercial engineering applications due to their excellent combination of strength and ductility at ambient temperature. However, the relatively low melting temperature (~430 °C) of the Mg17Al12 phase increases susceptibility to hot shortness during extrusion and ultimately limits the extrudability of the material; their maximum extrusion rate of 2.5 m/min is well below that attainable with Al alloys. In order to increase the viability of using extruded Mg alloys as an alternative to commercially used materials such as Al alloys, steels, polymers and ceramics, it is necessary to not only attain high strength but to also ensure excellent extrudability, which is directly related to productivity and cost. For this, we developed new alloy systems for high speed extrusion comparable to Al alloys and new extrusion processes for improving the strength of extruded Mg alloys. |