Al-Mg-Si系合金均匀化过程中β→α相转变动力学研究  

STUDY ON THE KINETICS OF PHASE TRANSFORMATIONβ→αIN THE HOMOGENEOUS HEAT TREATMENT OF Al-Mg-Si SERIES ALLOYS

作　　者：曹零勇[1] 郭明星[1] 崔华[2] 蔡元华[1] 张巧霞[1] 胡晓倩[1] 张济山[1] 

机构地区：[1]北京科技大学新金属材料国家重点实验室,北京100083 [2]北京科技大学材料科学与工程学院,北京100083

出　　处：《金属学报》2013年第4期428-434,共7页Acta Metallurgica Sinica

基　　金：北京市自然科学基金项目2112030;新金属材料国家重点实验室自主课题2012Z-07资助~~

摘　　要：根据已有的实验结果提出了Al-Mg-Si系合金均匀化过程中片层状β-AlFeSi相向球形α-Al(FeMn)Si相转变过程模型图,并据此采用稳态扩散理论对其转变动力学过程以及555℃不同时间相转变过程等进行了系统深入的研究.结果表明,均匀化温度T对β→α相转变的动力学影响很显著,温度越高,转变速率越快:而α相原始核心的大小只略微影响β相溶穿时间;α相核心间距l主要影响转变过程中β相的边界溶解阶段:β相的厚度对β→α相转变过程的影响最大,特别是溶穿阶段,随着厚度的增加,转变过程由β相边界溶解为主导的方式向由β相溶穿为主导的方式发生转变:当β相厚度分别为0.1,0.2和0.3μm时,理论预测发生熔断所需均匀化时间分别大于5,10和15 h,这与实际的实验结果非常吻合.此外,β相厚度小于0.3μm时,经16—24 h很容易达到转化率f(α)≥0.9,因此,除了优化均匀化过程进而更好地控制β→α相转变之外,合金熔铸工艺也应该尽量保证基体内的β相厚度小于0.3μm.According to the present experiment results about the transformation from/3-A1FeSi to a-Al（FeMn）Si phase in A1-Mg-Si series alloys, the model and kinetics of phase transformation, and microstructure evolution at 555 12 were systematically investigated. The results show that, the homogeneous temperature T can give a significant effect on the transformation kinetics, and with increasing T, the transformation rate increases fast. The nucleus radius of a phase only affects the breakthrough time along the thickness direction of /3 phase. The distance 1 between two c~ phases mainly has an influence on the dissolving of rim for /3 phase. The thickness of /3 phase normally has a greatest influence on the phase transformation β→ a, especially for the breakthrough stage of β phase, with increasing the thickness of β phase, the main transformation with longer time in the whole phase transformation process can changes from rim dissolving of/3 phaseto breakthrough along the thickness direction of ~ phase. The breakthrough time of/3 phases with the thickness of 0.1, 0.2 and 0.3 #m is above 5, 10 and 15 h, respectively, which corresponds with the real experiment results. In addition, if the thickness of 13 phase is smaller than 0.3 Ftm, the transformation rate f（c~） easily reaches above 0.9 after homogeneous heat treatment at 555 ~2 for 16--24 h. Therefore, the importance of optimizing casting process to make sure the thickness of β phase below 0.3 Itm, is the same as the homogeneous heat treatment for the better controlling the phase transformationβ→a

关 键 词：AL-MG-SI合金 均匀化热处理 相转变 动力学 模型 

分 类 号：TG166[金属学及工艺—热处理]