Thermal stability of substructures in 6000 series aluminum alloys containing Mn and Zr elements was investigated using plane-strain compression test. In order to form thermally stabilized substructures, the deformation parameters should be selected so as to correlate with kinetic precipitation during the deformation. For substructures of the alloys containing Mn and Zr elements, the substructures were stable during heat treatment at 540°C when the alloys were deformed at a temperature above 350°C. The sheets rolled above 350°C at a strain rate of under 3 s^-1 per pass showed the fibrous structure after the heat treatment at 580°C. The sheets with the fibrous structure had an average Lankford value larger than 1.

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Effect of microstructure on corrosion resistance and heat resistance of flame-resistant Ca-added magnesium alloy AZ61 (AZX612) were investigated. An extruded and twin-rolled casting magnesium alloys AZX612 were used with a view to better understanding the relationship between microstructure and these properties. The microstructures of the magnesium alloys were characterized by optical microscope (OM), X-ray diffraction (XRD) and scanning electron microscopy (SEM)/energy dispersive X-ray spectroscopy (EDS). The shapes of compounds in the alloys observed by EDS were significantly different; spherical distribution in grain for the extruded magnesium alloy and preferential formation on grain boundaries for the twin-rolled casting magnesium alloy. The different microstructure of the two alloys resulted in showing the different properties. Immersion test in 5 mass% NaCl aqueous solution revealed that the corrosion rates for the extruded and twin-rolled casting magnesium alloys AZX612 were estimated to be 6.5 and 15.0 mm/year, respectively, indicating that the corrosion resistance of the extruded magnesium alloys AZX612 were more superior than that of the twin-rolled casting one. On the contrary, the heat resistance of the alloy did not change depending on the microstructure.

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