Microstructural evolution and mechanical performance of cast Mg−3Nd−0.2Zn−0.5Zr alloy with Y additions  

Y元素对铸造Mg−3Nd−0.2Zn−0.5Zr合金显微组织演化及力学性能的影响

作　　者：He XIE Guo-hua WU Xiao-long ZHANG Zhong-quan LI Wen-cai LIU Liang ZHANG Bao-de SUN 谢赫;吴国华;张小龙;李中权;刘文才;张亮;孙宝德(上海交通大学材料科学与工程学院轻合金精密成型国家工程研究中心&金属基复合材料国家重点实验室,上海200240;上海航天精密机械研究所,上海201600)

机构地区：[1]National Engineering Research Center of Light Alloy Net Forming and State Key Laboratory of Metal Matrix Composites,School of Materials Science and Engineering,Shanghai Jiao Tong University,Shanghai 200240,China [2]Shanghai Spaceflight Precision Machinery Institute,Shanghai 201600,China

出　　处：《Transactions of Nonferrous Metals Society of China》2022年第10期3222-3237,共16页中国有色金属学报（英文版）

基　　金：supported by the National Natural Science Foundation of China(Nos.U2037601,51775334 and 51821001);the National Key Research&Development Program of China(No.2016YFB0701205);the Joint Innovation Fund of CALT and College,China(No.CALT2020-TS07);the Open Fund of State Key Laboratory of Advanced Forming Technology and Equipment,China(No.SKL2020005);the Research Program of Joint Research Center of Advanced Spaceflight Technologies,China(No.USCAST2020-14).

摘　　要：This work investigated the effects of different Y additions(0,1.5,3.0 and 4.5 wt.%)on the microstructural evolution and mechanical performance of cast Mg−3Nd−0.2Zn−0.5Zr alloy.The results show that as the Y content increases,the key secondary phases in as-cast alloys change from the Mg_(12)Nd type to the Mg_(24)Y_(5) type.Meanwhile,the number density of Zn−Zr particles in the grains of as-quenched alloys gradually decreases.HAADF-STEM observations of peak-aged samples reveal that element Y is greatly enriched in the globularβ¢precipitates,leading to a significantly increased volume fraction and promoted precipitation kinetics ofβ¢precipitates,resulting in enhanced strength of the alloy.Tensile tests reveal that,with the addition of 4.5 wt.%Y,the yield strength of the base alloy is substantially increased by 88 and 61 MPa after being aged at 200 and 225°C under peak-aged conditions,respectively.研究不同Y添加量(0、1.5%、3%和4.5%,质量分数)对铸造Mg−3Nd−0.2Zn−0.5Zr合金显微组织演变及力学性能的影响规律。结果表明,随着Y含量的增加,铸态合金中主要的第二相由Mg_(12)Nd型逐步转变为Mg_(24)Y_(5)型。同时,固溶态合金中的Zn−Zr相的数量随着Y含量的增加逐渐减少。利用HAADF-STEM技术观察到峰时效状态下Y元素在球状柱面β′相中显著富集。随着Y含量的增加,峰时效状态下合金中β′的体积分数显著增大。由于Y元素的加入,β′相析出动力显著增大,进而使得合金强度得到显著提高。拉伸试验结果表明,当Y添加量为4.5%(质量分数)时,在200和225℃峰值时效条件下合金屈服强度增量分别为88和61 MPa。

关 键 词：Mg−3Nd−0.2Zn−0.5Zr alloy Y alloying age-hardening response microstructural evolution mechanical properties 

分 类 号：TG146.22[一般工业技术—材料科学与工程]