双级时效对7N01合金组织与性能的影响

Effect of Two-Step Aging Treatment on Microstructure and Property of 7N01 Aluminum Alloy

摘要: 采用光学显微镜、透射电镜、差示扫描量热法、硬度和电导率，针对不同的时效制度对A7N01铝合金车体板材性能与微观组织演变的影响进行了深入的研究与探讨。优化设计了几种时效制度，并分别进行了对比试验。制定了适合实际生产的时效制度。研究结果表明，7N01合金适宜的双级时效工艺为105℃/12h + 150℃/8h，此时合金的硬度、电导率和抗拉强度分别为123 HV、36.3%IACS、375.8 MPa。双级时效后，合金的晶内组织为细小弥散分布的η’(MgZn2)相，晶界上有断续分布的晶界析出相MgZn2和较明显的无沉淀析出带。通过采用合适的双级时效工艺可在适当降低合金强度的前提下有效的改善晶界析出相的分布，提高了合金的抗应力腐蚀性能。

Abstract: The optical microscopy, transmission electron microscopy, differential scanning calorimetry, hardness and electric conductivity measurements are employed to focus on studying the effect of aging treatment on the microstructure evolution and property of 7N01 aluminum alloy. Several aging regimes were designed and optimized, and were dealt with contrast tests respectively. And a suitable aging regime for actual production was formulated. The results show that the hardness, conductivity and tensile strength of the alloy are 123 HV, 36.3%IACS and 375.8 MPa respectively after duplex aging (105˚C/12h + 150˚C/8h). The precipitations of η’ (MgZn2) appear on grain interior; the discontinuous distribution of MgZn2 phase and the precipitated-free zones (PFZ) appear on the grain boundaries. With an appropriate deduction of hardness, which effectively improves the distribution of the precipitates on the grain boundary, a better corrosion resistance can be achieved.