Takeshi Murakami

Upsetting textures in ZK60A magnesium alloy.

Texture measurements were made of upsetting forged disk to 50 and 70% reduction from semi-continuously cast rod and extruded rod of ZK60A alloy having weak [1120] and strong [1010] fiber texture parallel to rod axes respectively. The method of Harris for inverse pole figures of fiber textures was used. To verify if the method is appropriate for measurement of forging texture in magnesium, texture in extruded plate of AZ31 alloy was also measured. Initial textures changed during upsetting gradually to [0001] orientation parallel to upsetting direction, sharpness of these fiber texture being more shape at surface layer on disk than inner layer and at higher reduction. Textures in various location in disk from cast bar were uniform in comparison with that from extruded rod in which upsetting direction are parallel to extrusion direction.

Homogenization and age hardening behavior in AZ91D magnesium alloy solidified in water-cooled copper mold.

Microsegregation, homogenization behavior and aging characteristics were investigated in AZ91D magnesium alloy solidified in water-cooled copper mold. Specimens were extracted from a location 1mm away from chill plate because the microstructures with dendrite cell size from 10μm to 15μm were typical microstructure of diecastings. Minimum concentration of aluminum and zinc at a center of dendrite cell and amount of non-equilibrium eutectics crystallized at inter-dendrite cells were detected by means of X-ray microprobe analysis. Minimum concentration of aluminum and zinc were 4.5wt% and 0.35wt% respectively, and approximate homogenization was attained at 683K for 1h. Hardening was observed in aging of the alloy at the temperature from 373 to 443K without homogenization, the time to attain the maximum hardness being longer than the homogenized alloy.