超声铸造7085铝合金在热处理过程中的相变行为  

Phase Transformation Behavior of Ultrasonic-treated 7085 Aluminum Alloy During Heat Treatment

作　　者：李瑞卿[1,2] 李晓谦[1,2] 陈平虎[1,2] 黄明哲[1,2] 董方[1,2] 

机构地区：[1]中南大学高性能复杂制造国家重点实验室,长沙410083 [2]中南大学机电工程学院,长沙410083

出　　处：《材料工程》2016年第6期24-30,共7页Journal of Materials Engineering

基　　金：国家重点基础研究发展规划(973计划)资助项目(2012CB619504);国家自然科学基金面上项目(51475480)

摘　　要：采用OM,SEM,EDS和DSC等研究超声外场下凝固的结晶相在热处理过程中的相变行为,并利用扫描电镜原位加热台实时观察结晶相转变过程。结果表明:铝熔体经过超声外场处理后,晶粒组织由粗大树枝晶向细小等轴晶转变;超声铸锭的熔化焓为4.60J/g,低于常规铸锭的6.52J/g;超声外场处理后,铸锭中的θ相+T相共晶组织减少了29%;该铝合金铸锭中有θ相、T相、Al_3Fe相及Mg_2Si相4种结晶相,样品在DSC升温过程中,θ相颗粒逐渐溶入基体,T相转变成S相后在升温至高温峰时溶入基体,Al3Fe相在低温峰时转变成Al_7Cu_2Fe相残留在铸锭中,Mg_2Si相未见明显变化。The transformation behavior of secondary phases in conventional ingot and ultrasonic ingot during heat-treatment process were investigated by OM,SEM,EDS and DSC.Crystalline phase transition was observed by SEM with in situ heating station.The experiment results indicate that the ultrasonic melt treatment transforms from columnar crystals to equiaxed crystals,and obtains fine and uniform grains.The melting enthalpy of ultrasonic ingot is 4.60J/g,while the melting enthalpy of conventional ingot is 6.52J/g,combined with EDS analysis results,θphase and T phase are found to be reduced by 29% after ultrasonic melt treatment.The secondary phases in the ingots includeθphase,T phase,Al_3Fe phase and Mg_2Si phase.θphase is dissolved into matrix gradually,T phase transforms to S phase and is dissolved into matrix at high peak temperature,Al_3Fe phase transforms to Al_7Cu_2Fe phase at low peak temperature and remains in the ingots,Mg_2Si phase changes nothing during DSC analysis process.

关 键 词：超声铸造 结晶相 DSC分析 热处理 

分 类 号：TG166.3[金属学及工艺—热处理]