Al-Mg5.0-Mn0.5铝合金均匀化退火过程中Mg、Mn元素显微偏析的DICTRA模拟

DICTRA^(®)Simulation of Mg and Mn Micro-segregations in Al-Mg5.0-Mn0.5 Alloy During Homogenization Annealing

基于DICTRA动力学软件的MOB2和Al基数据库,对Al-Mg5.0-Mn0.5铝合金在470℃不同时间均匀化退火过程中Mg和Mn元素的显微偏析进行了模拟计算,并使用偏析因子来评价470℃不同时间均匀化退火过程中Mg和Mn元素的偏析程度。结果表明:在470℃不同退火时间后,Mg和Mn元素的偏析因子有如下变化:退火8.3 h后,Mg的偏析因子约为0.94,接近1.0,而Mn的偏析因子在0.78~1.3之间;在退火11.1 h后,Mg的偏析因子约为1.0,表示Mg的浓度基本扩散均匀,而Mn的偏析因子依然在0.78~1.3之间;退火27.8 h以后,Mn的偏析因子为0.8~1.3,与11.1 h相比只有微小的变化。根据计算结果,470℃下退火保温时间至少为11.1 h,Mg引起的微观偏析可通过均匀化退火消除;而Mn引起的微观偏析即使是470℃下退火保温时间为27.8~30 h仍然不能消除。通过对470℃不同均匀化退火时间合金元素的面分布对上述模拟结果进行了验证。本研究可为Al-Mg5.0-Mn0.5铝合金退火工艺的选择提供依据。

Micro-segregation of Mg and Mn in Al-Mg5.0-Mn0.5 alloy during homogenized annealing at 470℃was evaluated by computational simulation in DICTRA^(®)software,using MOB2 diffusion database and Al-based database.The segregation factor was used to predict the distribution of Mg and Mn at 470℃annealing temperature for different annealing time.Simulation results were compared with microstructure observations.Results show that after homogenizing at 470℃for 8.3 h,the segregation factor of Mg is about 0.94,close to 1.0;while,the segregation factor of Mn varies from 0.78 to 1.3.After homogenization annealing at 470℃for 11.1 h,the segregation factor of Mg is close to 1.0,concentration of Mg is basically uniform,and the range of segregation factor of Mn is almost unchanged.However,almost the same segregation factor of 0.8~1.3 is observed for Mn after annealing at 470℃for 27.8 h.According to the DICTRA calculation results,after homogenizing at 470℃for 11.1 h,the micro-segregation of Mg is almost eliminated.While the micro-segregation of Mn cannot be eliminated,even if the annealing holding time extends to 27.8 and 30 h.The simulation can provide a reference for the selection of annealing process of Al-Mg5.0-Mn0.5 alloy.