Sm对Mg-4Al-0.5Si-0.2Mn合金显微组织和力学性能的影响  

Effect of Sm on Microstructures and Mechanical Properties of Mg-4Al-0.5Si-0.2Mn Alloy

作　　者：刘峰 胡文鑫 杨正华[1,2] 何伟 王玮[2] LIU Feng;HU Wen-xin;YANG Zheng-hua;HE Wei;WANG Wei(State Key Laboratory of Baiyunobo Rare Earth Resource Researches and Comprehensive Utilization,Baotou 014030,China;Baotou Research Institute of Rare Earths,Baotou 014030,China)

机构地区：[1]白云鄂博稀土资源研究与综合利用全国重点实验室,内蒙古包头014030 [2]包头稀土研究院,内蒙古包头014030

出　　处：《稀土》2024年第5期9-16,I0003,共9页Chinese Rare Earths

基　　金：国家重点研发计划项目(2021YFB3501001);内蒙古自治区自然科学基金项目(2020MS05014)。

摘　　要：研究了Sm含量(0,0.2%,0.5%,0.9%,质量分数)对Mg-4Al-0.5Si-0.2Mn合金显微组织演变及室温力学性能的影响。通过透射电子显微镜(TEM)观察和Pandat热力学计算软件分析,阐释了Sm对合金组织中粗大汉字状Mg_(2)Si相的变质机制。研究结果表明,Mg-4Al-0.5Si-0.2Mn合金主要由ɑ-Mg、Mg_(2)Si和Mg_(17)Al_(12)相组成,添加0.2%和0.5%的Sm后,合金组织中汉字状Mg_(2)Si相的尺寸显著减小。当Sm含量增加至0.9%时,汉字状Mg_(2)Si相的形貌转变为棒状,尺寸进一步细化。此外,Sm的添加促使合金组织中形成了富Sm相。Sm变质Mg_(2)Si相的主要机制为:Sm原子在Mg_(2)Si晶体的固液界面前沿发生富集,形成成分过冷,有效抑制了汉字状Mg_(2)Si相的生长。Mg-4Al-0.5Si-0.2Mn-0.9Sm合金的室温抗拉强度、屈服强度和延伸率分别由未添加Sm前的173.8 MPa、106.8 MPa和3.5%提高到238.2 MPa、152.9 MPa和5.1%,这主要归因于Mg_(2)Si相形貌的改善和尺寸的细化。The effect of Sm content(0,0.2%,0.5%,0.9%,mass fraction)on microstructure evolution and mechanical properties of Mg-4Al-0.5Si-0.2Mn alloy at room temperature was investigated.Transmission electron microscopy(TEM)observation and thermodynamic calculation analysis by Pandat software were used to elucidate the Sm modification mechanism of the coarse Chinese script type Mg_(2)Si phase.The results show that Mg-4Al-0.5Si-0.2Mn alloy mainly consists ofɑ-Mg,Mg_(2)Si and Mg_(17)Al_(12) phases,the Chinese script type Mg_(2)Si phase can be refined significantly by adding 0.2%or 0.5%Sm.When the content of Sm increases to 0.9%,the morphology of Mg_(2)Si transforms to rod-like from Chinese script,and its size is further reduced.Furthermore,the addition of Sm leads to the formation of Sm-rich phases in the alloy microstructure.The modification mechanism of Mg_(2)Si with Sm addition is elucidated as follows:Sm atoms are enriched at the solid-liquid interface of Mg_(2)Si crystal,forming a compositional undercooling,effectively inhibiting the growth of the Chinese script type Mg_(2)Si phase.Compared with the Mg-4Al-0.5Si-0.2Mn alloy with no Sm addition,the ultimate tensile strength(UTS),yield strength(YS)and elongation(EL)of Mg-4Al-0.5Si-0.2Mn-0.9Sm alloy are increased from 173.8 MPa,106.8 MPa and 3.5%to 238.2 MPa,152.9 MPa and 5.1%,respectively,this is mainly attributed to the improvement of the morphology and refinement of the size of Mg_(2)Si phase.

关 键 词：Sm变质 Mg-4Al-0.5Si-0.2Mn合金 Mg_(2)Si 显微组织 力学性能 

分 类 号：TG146.2[一般工业技术—材料科学与工程]