超细晶7A52铝合金组织调控与动态性能研究

Al-7A52 alloy is a kind of Al-Zn-Mg alloys widely applied in light armor and aerospace industries. For further enhancing its service performance, it is required achieving both higher dynamic strength and better ductility and keeping good weldability at the same time. Therefore, the feasible way to improve mechanical properties is through microstructure control. In this class of precipitation-strengthened Al alloys, to obtain microstructure with extremely small and uniformly dispersed precipitates in the ultrafine grains together with reasonable dislocations density and distribution is one of the most effective methods to improve both strength and ductility. However, to date systematical investigation on microstructure control and dynamic mechanical properties in ultrafine-grained Al-7A52 alloy is unavailable. Thus，this proposal will focus on the research of microstructure control in ultrafine-grained Al-7A52 alloy, upon combining severe plastic deformation and heat treatment processing, and the effects of microstructure on strain rate and temperature dependence of dynamic mechanical properties. Then, the relationship of microstructure and dynamic mechanical properties and optimized microstructure possessing high strength and good ductility will be analyzed and achieved. In addition, dynamic deformation mechanism influenced by coupling strain rate and temperature and the effect of interaction among grain boundaries, dislocations and precipitate on the mechanical properties will be clarified. Consequently, strengthen mechanism of optimized microstructure in ultrafine grain precipitation-strengthened Al-7A52 alloy will be revealed. This research will contribute both theoretical and experimental foundation to reinforce application of Al-7A52 alloy in armor, aerospace and automobile field.

7A52铝合金是一种Al-Zn-Mg系高强可焊铝合金，在轻质装甲和航空航天等领域有很好的应用。为了满足更为苛刻的服役要求，需要其在保持良好焊接性能的基础上同时提高动态强度和塑性。为此，组织调控是比较可行的途径。晶粒超细化的同时调控位错组态和析出相的类型、大小、形态和分布是提高铝合金综合性能的有效方法之一。目前，超细晶7A52铝合金组织参数调控及动态力学性能的研究尚较欠缺。本课题拟通过大变形技术制备超细晶组织，并通大变形和热处理工艺的配合来调控精细组织参量，研究组织对动态力学性能及其应变率和温度相关性的影响，建立组织性能关系，优化得到高强韧性超细晶7A52铝合金；同时阐明动态变形机制的温度和应变率耦合效应，明确晶界、位错和析出相之间的交互作用对性能的影响，揭示优化组织的强化机制。项目的研究为7A52铝合金在装甲、飞行器和车辆上更好的服役奠定基础。

7A52铝合金是一种Al-Zn-Mg系高强可焊铝合金，在轻质装甲和航空航天等领域有很好的应用。为了进一步满足更为苛刻的服役要求，需要其在保持良好焊接性能的基础上同时提高动态强度和塑性。为此，组织调控是一条可行的途径。基于这一背景，本项目系统研究了ECAP和DPD工艺参数以及前后热处理工艺等对7A52铝合金精细组织演变的影响，即在获得超细晶组织的基础上调控位错组态和析出相的类型、大小、形态和分布，并研究了调控组织对准静态和动态力学性能的影响规律，建立了组织性能关系；优化出获得高强韧性以及具有优异高温动态新性能的超细晶7A52铝合金制备工艺方法；阐明了力学性能的应变率和温度相关性；建立了该合金的本构方程。项目的研究为7A52铝合金在轻质装甲、飞行器和车辆上更好的服役奠定了可靠的基础。