MgCO_3和CO_2气体对AM60B合金细化效果的影响  

Effects of MgCO_3 and Gaseous CO_2 on Grain Refinement in AM60B Alloy

作　　者：刘艳 龙思远[1,2] 袁颖 刘青[1] 

机构地区：[1]重庆大学材料科学与工程学院 [2]重庆大学国家镁合金材料工程技术研究中心

出　　处：《特种铸造及有色合金》2017年第11期1249-1253,共5页Special Casting & Nonferrous Alloys

摘　　要：为改善Mg-Al合金变质方法的不足,首先对常用的MgCO_3变质进行了热力学分析,并提出将CO_2气体直接通入AM60B合金熔体中,应能达到与MgCO_3变质相当甚至更优的晶粒细化效果。通过对比试验发现,MgCO_3可使AM60B合金的晶粒尺寸从未变质的213μm减小到113μm,硬度提高11.48%;用等量的CO_2气体处理,则使AM60B合金晶粒尺寸减小到了91μm,硬度提高了8.32%。通过SEM、EDS以及XRD分析表明,MgCO_3变质和CO_2气体变质具有相同的变质效果,这主要是熔体中的Al和C结合生成了Al4C3异质形核核心,进而细化AM60B合金的晶粒尺寸。In order to improve the grain refinement effect of Mg-Al alloys in aerospace industry,the calculation and analysis of Gibbs free energies of the metallurgical chemical reactions were carried out.The analysis results indicate that the de-composition reaction of MgCO3 in Mg-Al alloys melt is hard to be controlled,which influences the refinement effect on Mg-Al alloys.Then gaseous CO2 is thought to be the equal or even much better efficiency on the grain refinement of AM60 Balloy than MgCO3.MgCO3 was added into AM60 Balloy melt,as well gaseous CO2 with the same carbon content.The experiment results indicate that the average grain size of AM60 Balloy is decreased from 213μm to 113μm,while the microhardness is increased by 11.48% with the addition of MgCO3,and the average grain size of AM60 Balloy is decreased to 91μm while the microhardness is increased by 8.32% with addition of CO2 at equal carbon content.Based on SEM,EDS and XRD analysis,the refinement mechanism of MgCO3 is the same as that of gaseous CO2,that is,Al4 C3 generated by reaction of Al and C served as the heterogeneous nucleation substrates,which takes about the grain refinement of AM60 Balloy.

关 键 词：AM60B合金 热力学分析 变质处理 MGCO3 CO2 

分 类 号：TG146.22[一般工业技术—材料科学与工程]