Degraded creep resistance induced by static precipitation strengthening in high-pressure die casting Mg-Al-Sm alloy  

作　　者：Qiang Yang Shuhui Lv Bo Deng Norbert Hort Yuanding Huang Wei Sun Xin Qiu 

机构地区：[1]State Key Laboratory of Rare Earth Resource Utilization,Changchun Institute of Applied Chemistry,Chinese Academy of Sciences,Changchun 130022,China [2]School of Materials Science and Engineering,Changchun University of Science and Technology,Changchun 130022,China [3]MagIC-Magnesium Innovation Centre,Helmholtz-Zentrum Hereon,Max-Planck Strasse 1,Geesthacht 21502,Germany [4]Institute of Product Technology and Systems,Leuphana University Lüneburg,Universiättsalle,Lüneburg 121335,Germany

出　　处：《Journal of Materials Science & Technology》2024年第11期48-58,共11页材料科学技术（英文版）

基　　金：Chinese Academy of Sciences Youth Innovation Promotion Association(No.2023234);Scientific and Technological Developing Scheme of Jilin Province(No.20220402012GH);National Natural Science Foundation of China(No.U21A20323);Capital Construction Fund within the Budget of Jilin Province(No.2023C044-2);Major science and technology projects of Jilin Province and Changchun City(No.20220301026GX),the Special high-tech。

摘　　要：Relationship between precipitation strengthening and creep resistance improvement has been an impor-tant topic for the widespread applications of magnesium alloys.Generally,static precipitation strength-ening through thermal stable precipitates would generate satisfactory creep resistance.However,an op-posite example is presented in this work and we propose that the size of precipitates plays a crucial role in controlling the operative creep mechanisms.In addition,the precipitate components along with their crystal structures in the crept Mg-4Al-3Sm-0.4Mn samples with/without pre-aging were thor-oughly studied using Cs aberration-corrected high-angle annular dark-field scanning transmission elec-tron microscopy(HAADF-STEM).Previous aging generates a large density of fine precipitates(<~5 nm)homogeneously distributing in Mg matrix and exhibiting satisfactory strengthening effect.However,the number density of precipitate strings consisting of several or even dozens of relatively coarse precipitates(~10 nm)was significantly decreased at the same time.As revealed in this work,the relatively coarse particles in Mg matrix are much more efficient than the fine precipitates in promoting dislocation climb.Therefore,the rate-controlling mechanisms are transferred from dislocation climb to dislocation slip after previous aging,thus leading to degradation of creep resistance.Moreover,there are mainly five types of precipitates/clusters,namelyβ"-(Al,Mg)3Sm,Al5Sm3,ordered Al-Sm cluster,ordered Al-Mn cluster and ordered/unordered AlMnSm clusters.The crystal structures of the former two precipitates were discussed and the formation mechanisms of the precipitates/clusters were revealed.

关 键 词：Magnesium alloy Transmission electron microscopy PRECIPITATION Creep resistance SEGREGATION 

分 类 号：TG146.21[一般工业技术—材料科学与工程]