熱間圧延したAl-Zn-Mg-Cu合金の再結晶に及ぼすZrとCr添加の影響の差

抄録

Two sorts of Al-5.6%Zn-2.4%Mg-1.3%Cu alloys with 0.12%Zr and 0.26%Cr, respectively, were hot-rolled by 86% at 400°C and then solution-treated at 470°C. Transmission electron microstructures of both alloys in hot-rolled state are nearly the same. Subgrain structures of both alloys developed after disappearance of the η-particles are quite different. Zr-containing alloy shows an almost perfect subgrain structure, reflecting that the particle size of Al₃Zr is much smaller than that of E phase. In Zr-containing alloy, recrystallized grains have naturally appeared faster than in Cr-containing alloy and the grain growth is retained. Elongated grains in the rolling direction are commonly observed in both recrystallized alloys, and are attributed to the layered distribution of Al₃Zr or E particles in the rolled sheet.