Enhancing the ductility of cast Mg-Li alloys via dispersedα-Mg phase mitigating the dimension and distribution of interspersed eutectics along grain boundaries  

作　　者：Yu Wang Ziyang Xia Jingpeng Xiong Gang Zeng Penghao Wang Lan Luo Ruizhi Wu Jian Wang Yong Liu 

机构地区：[1]Key Laboratory of Light weight and high strength structural materials of Jiang xi Province,Advanced Manufacturing School of Nanchang University,Nanchang 330031,China [2]Key Laboratory of Superlight Materials&Surface Technology,Ministry of Education,Harbin Engineering University,Harbin 150001,China [3]Mechanical and Materials Engineering,University of Nebraska-Lincoln,Lincoln,NE 68588,USA

出　　处：《Journal of Magnesium and Alloys》2024年第11期4722-4739,共18页镁合金学报(英文)

基　　金：National Key Research and Development Program of China(Nos.2021YFB3501001);financial support from the National Natural Science Foundation of China(Nos.52061028,U21A2049,and 52061039);Natural Science Foundation of Jiangxi Province(Nos.20212BAB204049);Interdisciplinary Innovation Fund of Nanchang University(IIFNCU);China(No.9166-27060003-ZD05)。

摘　　要：Mg-Li alloys with high lithium concentrations possess a lightweight body-centered cubic(BCC)matrix structure(β-Li).Interspersed eutectics(primarily the reticulated I-phase)often form along phase boundaries(PBs)and grain boundaries(GBs)which strengthen the alloy but cause the loss of ductility due to the brittle behavior of I-phase.By modifying the Li content,we fabricated the(β+α)biphase Mg-Li alloy in which theα-Mg phase with a hexagonal close-packed structure(HCP)is embedded inβ-Li matrix,significantly increasing interface density.The high-density interfaces mitigate the distribution and dimension of the I-phase along GBs and PBs.The alloy exhibits enhanced ductility(elongation(EL)=17.8%)compared with the alloy without theα-Mg phase(EL=5.1%).Structural characterizations unveil the strengthening mechanism of the nanoscale B2(Li,Mg)3Zn-type precipitates in conjunction with the microscale I-phase.The(Li,Mg)3Zn nanophases augment the yield and ultimate tensile strength of the alloy without a discernible compromise in ductility,predominantly due to gliding dislocations cutting through the precipitates.In contrast,the microscale I-phase presents a formidable barrier to dislocation motion,facilitating dislocation pileups at interfaces and culminating in diminished ductility across the interface.In-situ stretching techniques were employed to scrutinize the microstructural evolution of alloys during tensile deformation,elucidating that the deformation compatibility of alloys correlates with the average size of the I-phase and their distribution along GBs and PBs.Corresponding to the orientation relationship(OR)between theα-Mg andβ-Li phases{110}Li//{0001}Mg and<ˉ111>Li//<11ˉ20>Mg,the slip continuity betweenα-Mg andβ-Li on plane pairs of{123}Li-{11ˉ22}Mg and{112}Li-{11ˉ22}Mg assures the deformation compatibility through facilitating the deformation across interfaces.Simultaneously,during the stretching process,the dispersed I-phase instigates the emergence of sporadic microcracks,indicating gradual damage e

关 键 词：Mg-Li alloys Deformation compatibility DUCTILITY Strengthening mechanism 

分 类 号：TG146.22[一般工业技术—材料科学与工程]