Al–6%Zn合金のセレーションの出現に及ぼす熱処理条件の影響

The eflfect of heat-treatment conditions on occurrence of serration in an Al–6 mass%Zn alloy was investigated. The specimen was aged for each time within 2600 ks mainly at 293 K after water-quenching from temperatures (TQ) ranging from 473 K to 853 K, and then tensile-tested at room temperature (293 K). The lower the TQ was and the shorter the aging time was, the more easily the serration occurred. As a result, in the case of TQ=473 K, the serration occurred even after aging for a long time such as 2600 ks, while in the case of TQ=773 K, the serration did not occur independent of aging conditions. Also, the serration occurred when specimens were furnace-cooled from 773 K to room temperature. From these results and those obtained by means of electrical resistivity measurements, it is considered that the serration in this alloy occurs when small GP zones such as Guinier radius under 1 nm or some solute clusters are formed.