钕钆变质镁铝基合金的固溶及时效行为  

Solution and aging behavior of Mg-Al alloy modified by Nd-Gd

作　　者：杨建东[1,2] YANG Jiandong(School of Material Science and Engineering,Xi’an University of Technology,Xi’an 710048,China;School of Aeronautical Materials Engineering,Xi’an Aeronautical Polytechnic Institute,Xi’an 710089,China)

机构地区：[1]西安理工大学材料科学与工程学院,陕西西安710048 [2]西安航空职业技术学院航空材料工程学院,陕西西安710089

出　　处：《西安工程大学学报》2023年第4期56-63,共8页Journal of Xi’an Polytechnic University

基　　金：国家自然科学基金面上项目(51771146);西安航空职业技术学院校助课题(22XHZK-04)。

摘　　要：为研究稀土元素Nd、Gd复合变质及热处理工艺对Mg-8Al合金组织的影响,分析与镁合金力学性能密切相关的β-Mg_(17)Al_(12)相及稀土相的组织演变规律。通过金相显微镜(OM)、X射线衍射仪(XRD)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)对试样微观组织进行表征,分析Mg-8Al-1Nd-1Gd合金在420℃固溶处理、210℃时效析出工艺中β-Mg_(17)Al_(12)及稀土相的形貌及分布规律。实验结果表明:向镁合金中添加Nd、Gd变质后共晶β-Mg_(17)Al_(12)由粗大的连续网状转变为细小不连续岛状,同时在晶界产生热稳定性良好的Al_(2)RE相;在固溶处理过程中共晶β-Mg_(17)Al_(12)相分解步骤为连续网状-不连续岛状-球状颗粒-完全溶解形成α-Mg单相过饱和固溶体,而Al_(2)RE相在热处理前后并未发生改变;时效析出的层片状及针状β-Mg_(17)Al_(12)相分别分布在晶界和晶内,稀土元素Nd和Gd的变质作用使析出的β-Mg_(17)Al_(12)相呈现细小、弥散的分布特征。In order to investigate the effect of Nd,Gd composite modification and heat treatment process on the microstructure of Mg-8Al alloy,we analyzed the evolution behavior of Mg_(17)Al_(12)closely related to mechanical properties of Mg alloys and rare earth phase.The microstructure of the specimens was characterized by metallographic microscope(OM),X-ray diffraction(XRD),scanning electron microscope(SEM)and transmission electron microscope(TEM),and the morphology and distribution ofβ-Mg_(17)Al_(12)and Al_(2)RE in Mg-8Al-1Nd-1Gd alloy during solution treatment at 420℃and aging precipitation at 210℃were observed.The experimental results show that the eutectic of Mg alloy after modification with Nd and Gd,β-Mg_(17)Al_(12)transforms from a continuous network to a fine discontinuous island and Al_(2)RE phase with good thermal stability is produced at the grain boundary.The phase decomposition process of eutecticβ-Mg_(17)Al_(12)in solution treatment is continuous network-discontinuous island-spherical particles.Finally,a supersaturatedα-Mg solid solution is formed,while Al_(2)RE phase do not change before and after heat treatment.Lamellar and acicular aging precipitationβ-Mg_(17)Al_(12)is distributed at the grain boundary and in the grain,respectively and the precipitatedβ-Mg_(17)Al_(12)presents fine and dispersed distribution characteristics under the modification of Nd and Gd.

关 键 词：变质镁合金 固溶时效 稀土相 析出相 

分 类 号：TG146.22[一般工业技术—材料科学与工程] TG113[金属学及工艺—金属材料]