车身板用6xxx系铝合金早期时效析出行为

The thermodynamic condition, selectivity of nucleation sites, crystal orientation relation with matrix, structure characteristics, size, quantity, dispersity and distribution of cluster and GP zone/transition phase during early-stage precipitation in three typical 6xxx series aluminum alloy sheets for automotive body were investigated by simulation method, in-situ observation of high resolution transmission electron microscopy (HRTEM), atom probe field ion microscope (APFIM), differential scanning calorimeter (DSC) and other microstructure determination analysis methods. The study was conducted in order to reveal the dynamic characteristics of nucleation, regression, development and growth of cluster in 6xxx series aluminum alloy, and to establish the dynamic evolution model of solute cluster at early stage precipitation, ultimately, to analyze the basic process of early-stage precipitation in 6xxx series aluminum alloy for automotive body sheet. Simultaneously, the effect of Cu and Mn on the vacancy migration energy, diffusion activation energy of solute atom, phase transformation driving force, phase transformation resistance and the structure characteristics of the early-stage precipitation in the 6xxx serials aluminum alloy were also studied to reveal the action mechanism of pre-aging on the stamping formability and bake hardening response ability of this kind of alloy sheet. Which can make breakthroughs in microstructure controlling and alloying of 6xxx series aluminum alloy for automotive body sheet.

采用计算模拟方法结合高分辨率透射电镜（HRTEM）原位观察、多维原子探针场离子显微镜（APFIM）、差热分析（DSC）等微观组织测定分析手段，针对三种典型车身用6xxx系铝合金板材，系统研究时效初期原子团簇、GP区/过渡相等微结构析出热力学条件、析出位置选择性、与母相的晶体学位向关系、原子团簇结构特征、尺寸、数量、弥散度及分布，揭示团簇微结构的形核、溶解、生长、长大动力学特征，建立时效初期微结构演变动力学模型，解析车身用6xxx系铝合金早期时效析出的基本过程。同时研究Cu、Mn对车身用6xxx系铝合金空位迁移能、溶质原子扩散激活能、相变驱动力、相变势垒及时效初期微结构特征的影响规律，揭示预时效同时改善铝板冲压成形性及烤漆硬化性的作用机制，以期在汽车车身用6xxx系铝合金微观组织结构调控及合金化原理方面取得新的突破。

采用计算模拟方法结合组织性能测定分析手段，研究了汽车车身板用Al-Mg-Si合金时效初期原子团簇、GP区/过渡相等微结构析出热力学条件、析出位置选择性、与母相的晶体学位向关系、原子团簇结构特征、尺寸、数量、弥散度及分布。揭示了团簇微结构的形核、溶解、生长、长大动力学特征，建立了时效初期微结构演变动力学模型，解析了车身用Al-Mg-Si合金早期时效析出的基本过程，揭示预时效同时改善铝板冲压成形性及烤漆硬化性的作用机制。同时明确了含Mn和Cr的车身Al-Mg-Si合金中弥散相的转变规律。建立了Al-Mg-Si合金板材强度预测模型，开发出新型低成本短流线制备工艺技术。