高Mg含量对Al-Si-Cu-Mg合金凝固过程和组织演变的影响  

Effect of High Mg Content on Solidification Process and Microstructure Evolution of Al-Si-Cu-Mg Alloy

作　　者：陈安柱[1] 周鹏飞[1,2] 陆从相 CHEN An-zhu;ZHOU Peng-fei;LU Cong-xiang(Yancheng Vocational Institute of Industry Technology,Yancheng 224005,Jiangsu,China;Material science and Engineering School,Yancheng Institute of Technology,Yancheng 224051,Jiangsu,China)

机构地区：[1]盐城工业职业技术学院,江苏盐城224005 [2]盐城工学院材料工程学院,江苏盐城224051

出　　处：《铸造》2022年第3期315-322,共8页Foundry

基　　金：2019校级创新团队项目(YGYKT-04);2019校级自然科学基金项目(ygy2019-04、ygy20-04);江苏高校“青蓝工程”。

摘　　要：为开发新型耐磨合金,利用热力学计算、热分析以及组织分析等手段研究了高Mg(8wt.%~20wt.%)含量对Al-17Si-4.5Cu-xMg合金凝固行为及组织演变的影响。结果表明:Mg含量的增加显著改变了初生Mg_(2)Si的形貌以及凝固行为。ThermoCalc模拟预测合金凝固过程中有6个反应,即形成初生Mg_(2)Si;两个二元共晶反应,形成(Mg_(2)Si+Si)或(Mg_(2)Si+α-Al)相;三元共晶反应形成(Mg_(2)Si+Si+α-Al);以及凝固后期共晶反应形成Q-Al_(5)Mg_(8)Cu_(2)Si_(6)和θ-Al_(2)Cu相。所研究的四种合金中除了有上述相外,还有富Fe相。Mg含量达到17.2wt.%时初生Mg_(2)Si的形貌由多面体状转变为树枝晶状。继续增加Mg的含量,初生Mg_(2)Si形貌不变,但枝干变粗。In the interests of pursuing the development of new wear-resistant alloys,the current study was undertaken to investigate the effects of Mg additions ranging from 8wt.% to 20wt.% on the solidification behavior and microstructure evolution of hypereutectic Al-17Si-4.5Cu-Mg alloy using thermodynamic calculations,thermal analysis,and extensive microstructural examination.The Mg level strongly influenced the microstructural evolution of the primary Mg_(2)Si phase as well as the solidification behavior.Thermodynamic predictions using ThermoCalc software reported the occurrence of six reactions,comprising the formation of the primary Mg_(2)Si;Two pre-eutectic binary reactions,forming either Mg_(2)Si+Si or Mg_(2)Si+α-Al phases;The main ternary eutectic reaction forming Mg_(2)Si+Si+α-Al;Two post-eutectic reactions resulting in the precipitation of the Q-Al_(5)Mg_(8)Cu_(2)Si_(6) and θ-Al_(2)Cu phases,respectively.Microstructures of the four alloys studied confirmed the presence of these phases,in addition to that of the Fe-bearing phase.The morphology of the primary Mg_(2)Si phase changed from an octahedral to a dendrite form at 17.2wt.% Mg.Any further Mg addition only coarsened the dendrites.Image analysis measurements revealed a close correlation between the measured and calculated phase fractions of the primary Mg_(2)Si and Si phases.ThermoCalc and Scheil calculations were in good agreement with the experimental results obtained from the microstructural and thermal analyses.

关 键 词：Al-17Si-4.5Cu-Mg 初生Mg_(2)Si 形貌 Mg含量 凝固过程 

分 类 号：TG146.22[一般工业技术—材料科学与工程]