4种均匀化态Al-Zn-Mg-Cu合金的淬透性

摘要

通过末端淬火方法研究7075,7050,7055和7085这4种均匀化态合金的淬透性,采用扫描电镜和透射电子显微镜对微观组织进行分析.研究结果表明:这4种均匀化态合金距离喷水端98 mm处的维氏硬度比3 mm处的维氏硬度分别下降33％,6％,7％和5％,7075合金淬透层深度为23 mm,其余3种合金淬透层深度均在100 mm以上;7075合金慢速淬火时,更多大尺寸的η平衡相和T相倾向于在非共格的E相上析出;时效后平衡相的周围出现明显无沉淀析出带,导致维氏硬度明显下降,淬透性大大降低,而其余3个合金中弥散粒子(Al3Zr)与基体共格,析出的平衡相粒度较小且数量较少,因而淬透性均较好.%The hardenabilities of 7075,7050,7055 and 7085 homogenized aluminum alloys were studied by end quenching test,scanning electron microscopy and transmission electron microscopy.The results show that hardness difference of the four alloys is 33％,6％,7％ and 5％ respectively from spray end to the other one.The hardened depth is about 23 mm for 7075 and above 100 mm for the other three alloys.In 7075 alloy,more equilibrium η and T phases particles with larger size tend to precipitate at incoherent E phase dispersoids during slow quenching.After aging,obvious PFZ can be around the equilibrium phases,causing hardness to decrease distinctly and hardenability to reduce greatly.For other three alloys,Al3Zr dispersoids are coherent with the Al matrix,which results in less precipitation of smaller equilibrium phases and therefore leads to good hardenability.