冷轧变形Al-Cu合金再结晶Σ3晶界研究

Study on Σ3 boundaries in an cold rolled and recrystallized Al-Cu alloy

选用经反复多向锻造和再结晶退火的晶粒组织细小均匀且晶体取向均匀的Al-1.2%Cu合金(质量百分数)为实验材料,三个平行试样分别进行厚度减缩量为10%、20%和30%的室温轧制变形后,在390℃退火2min,利用基于体视学原理和电子背散射衍射技术(EBSD)的五参数分析法(FPA)对其Σ3晶界比例和成分进行测定和分析。结果表明,退火前的轧制变形量对Al-Cu合金再结晶Σ3晶界有显著影响。轧制变形量为10%时,再结晶Σ3晶界相对比例由初始状态时的13%提高到22%;轧制变形量增加到20%时,这一比例提高到32%;轧制变形量进一步增加到30%时,这一比例有所下降。随着轧制变形量由10%增加到30%,再结晶Σ3晶界中的共格成分、即共格孪晶界比例在明显增加。

Al-1. 2% Cu（ mass fraction） alloy, which had been subjected to a process of multi-directional forging and recrystallization annealing by which a fine equiaxed-grain microstructure without preferred orientation was obtained,was chosen as experimental material in current work. Three parallel samples were cold rolled with thickness reduction of 10%,20% and 30%,respectively,followed by a recrystallization annealing at 390 ℃ for 2 minutes. Then,electron backscatter diffraction（ EBSD） coupled with five parameter analysis（ FPA） were used to characterize the Σ3 boundaries in the samples as processed. The results show that the cold rolling has dramatic effects on the formation of Σ3 boundaries during subsequent recrystallization annealing. When the thickness reduction of cold rolling is 10%,the relative frequency of Σ3 boundaries after annealing increases from its initial 13% to 22%,and it further reaches to 32% when thickness reduction of cold rolling reaches 20%. With further increment of thickness reduction of cold rolling from 20% to 30%,the relative frequency of Σ3 boundaries after annealing decreases obviously. The results also indicate that,with increment of thickness reduction of cold rolling,the frequency of coherent component of Σ3 boundaries after annealing is increasing.