(中南大学 材料科学与工程学院，长沙 410083)
摘 要: 采用硬度测试、电导率测试及透射电镜观察，研究固溶后降温至440 ℃预析出处理时间对7A55铝合金板材力学和腐蚀性能的影响。结果表明：随预析出处理时间的延长，基体析出相逐渐增多且长大，导致合金时效后硬度和强度先提高而后降低；晶界析出相逐渐长大，晶界无沉淀析出带宽化，晶界相不连续性先提高而后降低，导致合金抗晶间腐蚀和剥落腐蚀性能也先升高而后降低。
关键字: 7A55铝合金；预析出；晶间腐蚀；剥落腐蚀
（School of Materials Science and Engineering, Central South University,Changsha 410083, China）
Abstract:The influence of pre-precipitation at 440 ℃ after solution on the mechanical properties and corrosion resistance of aluminium alloy 7A55 was investigated by hardness tests, conductivity tests and transmission electron microscopy (TEM). The results show that with increasing the pre-precipitation time, the density of the precipitates in the matrix becomes higher and then the size becomes larger. As a result the hardness and strength increase first and then decrease. At the same time, the particles at the grain boundaries become larger with wider precipitate free zone, and the discontinuity of these particles increases first and then decreases with increasing pre-precipitation time. Consequently, intergranular corrosion and exfoliation corrosion resistance increase first and then decrease.
Key words: 7A55 aluminium alloy; pre-precipitation; intergranular corrosion; exfoliation corrosion
