摘要
采用差示扫描量热法(DSC)和硬度测量方法对汽车用A1-0.6Mg-0.9Si-0.2Cu(质量分数,%)合金不同状态析出动力学进行了研究.结果表明,T4态合金升温到100—150℃时,DSC曲线出现低温析出峰,而T4P态合金无此低温析出峰;经过T4P处理的合金其β″相析出峰位向低温移动.利用A-J-M方法计算合金不同相析出动力学参数,结果表明,T4和T4P态合金GP区溶解激活能分别为66和119 kJ/mol,β″相析出激活能分别为114和60 kJ/mol;T4态合金的溶解和析出动力学方程分别为:Y_(GP)=1-exp[-1.3×10~7texp(-7977/T)],Y_β″=1-exp[-4.7×10^(22)t^2exp(-27484/T)];T4P态合金的溶解和析出动力学方程分别为:Y_(GP)=1-exp[-2.4×10^(13)texp(-14345/T)],Y_β″=1-exp[-2.9×10^(11)texp(-14392/T)].此外,在185℃时效过程中,随着时效时间的延长,T_4和T4P态合金的硬度均先不断增加达到峰值后趋于平缓,但是T4态合金经20 min时效处理后出现硬度下降,而T4P态合金无此现象,利用GP区回溶和β″相析出动力学对此变化规律进行了很好的解释.
ABSTRACT The kinetics of precipitation in Al-0.6Mg-0.9Si-0.2Cu （mass fraction, %） alloy under different conditions was investigated by differential scanning calorimetric analyses （DSC） and micro- hardness measurements. The results show that, an exothermic peak at about 100--150 E can be observed in the DSC curve for the nature aged （T4） alloy, but no peak for the pre-aged （T4P） alloy, and the peak corresponding with f/phase moves toward the low temperature zone for T4P alloy. The fraction of transformation Y, the rate of transformation dY/dT, and the kinetic parameters such as activation energy Q and frequency factor k0 for GP zones dissolution and β phase transformation were calculated by Avrami Johnson-Mehl equation. The values of activation energy for CP zones dissolution after natural aging and pre aging were 66 and 119 k J/tool, respectively, and the values for phase formation after natural aging and pre-aging were 114 and 60 kJ/mol, respectively.
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2013年第12期1604-1610,共7页
Acta Metallurgica Sinica
基金
国家高技术研究发展计划项目SS2013AA032103
中央高校基本科研业务费项目FRF-TD-12-001资助~~
