7A36铝合金挤压板材的TTT曲线与淬火析出行为  

TTT diagrams and quenching precipitation behavior of 7A36 aluminum alloy extruded plate

作　　者：刘佳[1,2] 马志民 刘胜胆[2,3,4] 邓运来 张新明[3,4] LIU Jia;MA Zhimin;LIU Shengdan;DENG Yunlai;ZHANG Xinming(Baotou Vocational&Technical College,Baotou 014030,Inner Mongolia,China;Industry-University-Research-Application Innovation Center,School of Materials Science and Engineering of Central South University-Baotou Vocational&Technical College,Baotou 014030,Inner Mongolia,China;School of Materials Science and Engineering,Central South University,Changsha 410083,China;Key Laboratory of Non-ferrous Metal Materials Science and Engineering(Ministry of Education),Central South University,Changsha 410083,China)

机构地区：[1]包头职业技术学院,内蒙古包头014030 [2]中南大学材料科学与工程学院-包头职业技术学院产学研用创新中心,内蒙古包头014030 [3]中南大学材料科学与工程学院,长沙410083 [4]中南大学有色金属材料科学与工程教育部重点实验室,长沙410083

出　　处：《材料工程》2023年第11期134-143,共10页Journal of Materials Engineering

基　　金：内蒙古高等学校科学研究项目(NJZZ23102,NJZY21092);院立科学研究项目(KJ202108,KJ202204);国家重点研发计划资助项目(2016YFB300901)。

摘　　要：采用分级淬火实验获得7A36铝合金挤压板材的时间-温度-转变(TTT)曲线,通过计算相图结合光学显微镜、扫描电镜、透射电镜、扫描透射电镜和高分辨透射电镜等分析手段研究淬火析出行为。结果表明:抑制合金相转变0.5%的临界淬火速率约为15.7℃/s,10%TTT曲线的鼻尖温度约为338℃,鼻尖处的转变时间约为22 s。在不同等温保温样品中观察到η(MgZn_(2))相、T(Al_(2)Zn_(3)Mg_(3))相、S(Al_(2)CuMg)相和富Cu-Zn的Y相等淬火析出相,并将其析出行为描述在TTT曲线中,绘制成时间-温度-析出相图。η平衡相依次在晶界、亚晶界和弥散粒子上形核长大,等温保温的温度越高,η相的尺寸越大。电导率随保温温度的升高先增大后减小;在420℃等温保温时,电导率升高是由于η相和T相的析出引起,在330℃和240℃等温保温时,电导率升高是由于η相、T相、S相和Y相析出的共同作用。The time-temperature-transformation(TTT)diagrams of 7A36 aluminum alloy extruded plate were determined by an interrupted-quench method.The quenching precipitation behavior was investigated by calculate phase diagram(CALPHAD)combined with optical microscopy(OM),scanning electron microscopy(SEM),transmission electron microscopy(TEM),scanning transmission electron microscopy(STEM)and high-resolution transmission electron microscopy(HRTEM).The results show that the critical quenching rate for inhibiting the phase transition of 7A36 aluminum alloy by 0.5% is about 15.7℃/s.Based on 10% TTT diagram,the nose temperature is determined to be about 338℃ with the transformation time of about 22 s.The precipitation of η(MgZn_(2)),T(Al_(2)Zn_(3)Mg_(3)),S(Al_(2)CuMg)or Cu-Zn rich Y phases can be found depending on different isothermal holding temperatures and time,and the precipitation behavior is described in the TTT curve,which is described as a time-temperatureprecipitation diagram.η equilibrium phase tends to occur at grain boundary(GB)first and then at sub-grain boundary(SGB)and on dispersoids in the interior of grains,at higher isothermal holding temperature,the size of η phase is larger.The electrical conductivity increases first and then decreases with the increase of holding temperature;isothermal holding at 420℃,the increase of electrical conductivity is caused by precipitation ofηphase and T phase,while at 330℃ and 240℃,the increase of electrical conductivity is due to the precipitation ofηphase,T phase,S phase and Y phase.

关 键 词：7A36铝合金 时间-温度-转变曲线 淬火敏感性 淬火析出相 

分 类 号：TG146.2[一般工业技术—材料科学与工程]