Effects of a novel refiner Al-3Ti-4.35La combined with Sr on microstructure and mechanical properties of as-cast A356 alloy  

作　　者：Mei Xu Wan-wu Ding Li-wen Hu Shi-hao Chen Hai-xia Zhang Hai-cun Yu Wen-jun Zhao 

机构地区：[1]School of Materials Science and Engineering,Lanzhou University of Technology,Lanzhou 730050,China [2]State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals,Lanzhou University of Technology,Lanzhou 730050,China

出　　处：《China Foundry》2024年第6期641-650,共10页中国铸造（英文版）

基　　金：financially supported by the National Natural Science Foundation of China(Grant No.52161006);an Industrial Support Plan Project of Gansu Provincial Department of Education(2021CYZC-23);the Gansu Key Research and Development Program(21YF5GD183);the Jiayuguan Science and Technology Planning Project(21-10);the China Postdoctoral Science Foundation Project(2019M653896XB)。

摘　　要：It is a practically significant issue to refine and modify industrial Al-Si casting alloy to improve its properties.In the present study,a novel refiner Al-3Ti-4.35La alloy,prepared by a melt-reaction method,was used,combined with Sr to refine the as-cast A356 alloy.Their effects on the as-cast microstructures and mechanical properties of A356 alloy were investigated.The results indicate that the combined addition of Al-3Ti-4.35La intermediate alloy and Sr can improve the microstructure and enhance the mechanical properties of A356 alloy.After adding 0.3wt.%Al-3Ti-4.35La and 0.03wt.%Sr to the as-cast A356 alloy,the average grain size ofα-Al decreases from 693.47μm to 264.13μm(a decrease of 61.91%),the secondary dendrite arm spacing(SDAS)is decreased by 47.8%from 32.09μm to 16.75μm,and the eutectic Si is transformed from an acicular structure to short rods and a granular structure.The ultimate tensile strength(UTS)and elongation(EL)of the as-cast A356 alloy modified by Al-3Ti-4.35La and Sr reach 216.3 MPa and 10.6%,which are enhanced by 29.54%and 134.66%compared with the unmodified alloy,respectively.The fracture mode is transformed from transgranular fracture to intergranular fracture,and the ductile toughness of the alloy is improved.After adding the Al-3Ti-4.35La and Sr,the undercooling for the nucleation ofα-Al and eutectic Si increases,leading to an accelerated nucleation rate and an increased number of nuclei,which shortens the duration of the eutectic reaction and consequently inhibits grain growth.

关 键 词：A356 alloy Al-3Ti-4.35La SR REFINER grain refinement microstructure mechanical properties 

分 类 号：TG146.21[一般工业技术—材料科学与工程]