【摘要】 采用旋转结晶工艺制备高镁含量的Al-10Mg合金坯料,并对其进行673K/24h固溶处理及单轴热压缩变形。通过流变应力行为及微观组织表征来分析合金动态再结晶过程中项链组织的形核及扩展行为,特别地,分析了变形温度和应变率对项链组织扩展行为的不同影响。研究表明:大角度晶界的凸出是项链组织首层再结晶晶粒的形核方式,Al-10Mg合金变形组织中有微带、应变诱发的小角度晶界和回复形成的小角度晶界等3种亚晶界。随变形温度升高,微带和回复形成的小角度晶界逐渐消失,应变诱发的小角度晶界形核及由大角度晶界迁移造成的再结晶晶粒粗化是项链组织扩展的主要方式;随应变率的降低,未再结晶的变形晶粒被划分为低取向差中心区、外层再结晶晶粒区和处于中间层的富集小角度晶界的网状结构区等3部分,应变率从6.94×10^-1 s^-1降至6.94×10^-2 s^-1时再结晶晶粒面积占比减小,而当应变率从6.94×10^-2 s^-1进一步降至6.94×10^-3 s^-1时,再结晶晶粒面积占比显著提高。更多还原

【Abstract】 The formation and expansion of necklace structure in an Al-10 Mg alloy were studied. The alloy was produced by centrifugal casting, followed by 673 K/24 h solid solution treatment and hot uniaxial compression. The different effects of temperature and strain rate on expansion of necklace structure were particularly clarified. The results show that bulging is the nucleation type of first layer in necklace structure, and three different types of subboundary are found in the deformation microstructure. When the temperature increases, microband and recovered subboundary are gradually eliminated; strain-induced subboundary nucleation and recrystallized grain coarsening become the main way of necklace expansion. When the strain rate decreases, low angle grain boundary is accumulated. Three regions denoted by low misorientation region in interior, new grains in out layer and net structure of subboundary concentration in middle are observed in parent grains. The proportion of recrystallized grain area decreases when the strain rate changes from 6.94×10^-1 s^-1 to 6.94×10^-2 s^-1, and then significantly increases as strain rate further decreases from 6.94×10^-2 s^-1 to 6.94×10^-3 s^-1.更多还原