チルキャストしたAl-Li-Ti合金の複合析出物による延性改善

抄録

Composite precipitates consisting of the core particle, presumably Al₃ (Li, Ti) and the outer shell of δ'-Al₃Li phase were formed by a two-stage aging(at 500°C and then at 180 or 190°C) in chill cast specimens of Al-(1.6-2.3) wt% Li-(0.45-0.95) wt%Ti alloys. Al-Li-Ti ternary alloys containing both the composite precipitates and δ' particles in the peak-aged condition, showed a considerably superior ductility to that of the peak-aged Al-Li binary alloy together with a higher strength. Bow-out dislocations and tangled dislocations were observed near the composite precipitates in the tensile-strained specimens of Al-Li-Ti alloys and shear type of transgranular fracture were recognized in SEM fractography of the peak-aged specimens of Al-Li-Ti alloys containing the composite precipitates, whereas planar slip of dislocations and typical intergranular fracture were observed in the peak-aged specimens of Al-Li binary alloys. The composite precipitates improve ductility by retarding the planar slip mode in Al-Li-Ti alloys.