7N01アルミニウム合金の時効特性に及ぼす化学成分の影響

抄録

The influence of the room temperature pre-aging (RTPA) conditions on the strength of 7N01 aluminum alloy in T6 temper was changed by the zinc and magnesium contents. When both the zinc and magnesium contents were the lowest and the RTPA was omitted, the strength became the lowest because the aging rate during artificial aging decreased and a non-homogeneous precipitation of the η′ phase occurred. On the other hand, the η′ phase became finer and the strength in T6 temper became higher as the RTPA was longer and higher. Also, the two-step artificial aging resulted in a higher strength. It was considered that the GP(I) zones, which formed during RTPA, dissolved and the GP(II) zones formed during heating process of the artificial aging. Because the GP(II) zones were the precursor to the h9 phase, the strength became higher by the RTPA and the two-step aging. Furthermore, the influence of RTPA on the strength in T6 temper decreased with the increasing zinc and magnesium contents, and it almost disappeared when both the zinc and magnesium contents were maximum values. It was considered that the aging rate increased, and the GP(I) and GP(II) zones adequately formed during the heating stage of the artificial aging process because the solute atoms of the zinc and magnesium were sufficiently present.