微量元素La和Al-5Ti-1B复合细化Al-Cu机理  

Mechanism of grain refinement in Al-Cu alloy by adding trace La and Al-5Ti-1B

作　　者：杨林洁 张丽丽[1,2] 江鸿翔[1,2] 何杰[1,2] 赵九洲[1,2] Yang Lin-Jie;Zhang Li-Li;Jiang Hong-Xiang;He Jie;Zhao Jiu-Zhou(Shi-changxu Innovation Centre for Advanced Materials,Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,China;School of Materials Science and Engineering,University of Science and Technology of China,Shenyang 110016,China)

机构地区：[1]中国科学院金属研究所,师昌绪先进材料创新中心,沈阳110016 [2]中国科学技术大学材料科学与工程学院,沈阳110016

出　　处：《物理学报》2023年第8期264-271,共8页Acta Physica Sinica

基　　金：国家重点研发计划(批准号:2021YFA0716303);中国载人航天工程;国家自然科学基金(批准号:51901231,51971227)资助的课题

摘　　要：实验研究了复合添加微量元素La和Al-5Ti-1B对Al-Cu合金凝固组织的影响,发现与单独添加Al-5Ti-1B相比,复合添加Al-5Ti-1B和微量La可进一步细化Al-Cu合金凝固组织,降低α-Al的形核过冷度.结合高分辨透射电镜表征和理论计算,探明了复合添加微量元素La和Al-5Ti-1B对Al-Cu合金凝固组织的细化机理:经Al-5Ti-1B细化处理的Al-Cu合金凝固时,Cu富集于α-Al与TiB_(2)粒子的界面处,增加了α-Al与TiB_(2)粒子间的错配度,降低了TiB_(2)粒子对α-Al的异质形核能力;添加微量的La能有效降低α-Al与TiB_(2)粒子间的错配度,减小TiB_(2)粒子和α-Al间的界面能及接触角,从而提高TiB_(2)粒子促进α-Al的异质形核能力和Al-5Ti-1B对Al-Cu合金晶粒的细化效果.Grain refinement of aluminium alloys can not only reduce the defects(such as segregation and hot tearing)but also improve the mechanical properties.Adding Al-5Ti-1B master alloy to the melt has become a common method to refine the solidification microstructure of aluminium alloys.A lot of researches have been carried out to uncover the grain refining mechanisms as well as to show the microstructure formation under the effect of grain refiner.These researches demonstrated that the grain refining efficiency is closely related to the number density of TiB_(2) particles as well as the solute Ti concentration in the melt.However,there exist still problems to be resolved,such as the limited grain refinement potency of Al-5Ti-1B master alloy.Recently,the addition of trace La to the melt has attracted much attention to control the microstructure of aluminium alloys.The Al-Cu alloys are widely applied to the automobile and aerospace fields due to their high strength,good ductility and high temperature properties.It has been reported that Cu can segregate to Al/TiB_(2) interface in the Al-Cu melt inoculated with Al-5Ti-1B master alloy.But the effect of Cu segregation on the grain refinement result is not clear yet.Meanwhile,whether the grain refinement effect of Al-5Ti-1B master alloy on Al-Cu alloy can be improved by the addition of trace La has not been reported.Solidification experiments are carried out for Al-2Cu alloy with the addition of Al-5Ti-1B master alloy+trace La.The synergistic effect of trace La and Al-5Ti-1B on the solidification microstructure of Al-2Cu alloy is investigated.It is found that trace La can effectively enhance the refinement result of Al-2Cu alloy and further diminish the nucleation undercooling.Experimental and calculated results demonstrate that solute Cu segregates to the Al/TiB_(2) interface and thus increases the interatomic spacing mismatch between Ti(0001)plane of the TiB_(2) particles and the interfacial monolayer,while La segregation reduces the interatomic spacing mismatch.The trace

关 键 词：晶粒细化 微量元素 富集 铝合金 

分 类 号：TG146.21[一般工业技术—材料科学与工程]