通过拉伸实验, OM, SEM, TEM观察以及EBSD测试等手段研究了不同尺寸粒子对Al-Mg-Si-Cu系合金板材力学性能、组织和织构的影响规律. 结果表明, 随着溶质元素浓度的增加, 合金屈服强度和抗拉强度均不断增加, 但是延伸率却略有降低, 且3个方向存在一定差异. 此外, 合金的平均塑性应变比 \begin{array}{c}{\displaystyle \stackrel{-}{r}}\end{array}也随溶质元素浓度增加而增加. 3种合金基体内的不同尺寸粒子主要为Mg₂Si, Al₁₅Mn₃Si₂和α-Al(Fe, Mn)Si富铁相, 这些粒子尺寸和浓度搭配合理不仅可以诱发粒子刺激形核效应(particle stimulated nucleation, 简称PSN), 而且可有效抑制晶粒长大, 最终使得合金固溶时形成大量细小再结晶晶粒, 而织构组分以旋转立方织构Cube_ND18, Goss织构{011}<100>, P{011}<122>和Cu{112}<111>为主. 此外, 根据合金成分、热加工工艺以及显微组织间的定量关系提出了不同尺寸粒子影响再结晶形核和长大过程的模型示意图。

To reduce the weight of car body, Al-Mg-Si-Cu alloys have been used to produce outer body panels of automobiles due to their relatively good formability in the solution treated condition and high strength in the age hardened condition. However, their formability is significantly poor compared to that of steels, which are the major drawbacks to wide-scale application of aluminum in the automotive industry. The microstructural characteristics developed during recrystallization, most notably grain size and crystallographic texture, play a dominant role in controlling the mechanical properties and formability of sheet in the T4 condition. In this work, the effect of particles with different sizes on the mechanical properties, microstructure and texture of Al-Mg-Si-Cu alloys was studied through tensile test, OM, SEM, TEM and EBSD measurement. The results reveal that with increase of solute concentration, the average plastic strain ratio, yield strength and ultimate tensile strength increase, but the elongation decreases and with different extents in the three directions. In addition, the number of observed particles with different sizes in the alloy matrix such as Mg₂Si, Al₁₅Mn₃Si₂ and α-Al(Fe, Mn)Si phases also increases. When the size and concentration of these particles are controlled appropriately, lots of finer recrystallized grains can form during solution treatment due to the particle stimulated nucleation (PSN) effect of coarse particles and pinning effect of finer particles. The main texture components include Cube_ND18, Goss{011}<100>, P{011}<122> and Cu{112}<111> for the alloy with fine-grained structure. At last, according to the relationship among alloy composition, thermomechanical processing and microstructure, the model of nucleation and growth of recrystallized grains affected by the particles with different sizes was also proposed。