Microstructure evolution and mechanical properties of a large-sized ingot of Mg-9Gd-3Y-1.5Zn-0.5Zr (wt%) alloy after a lower-temperature homogenization treatment
Microstructure evolution and mechanical properties of a large-sized ingot of Mg-9Gd-3Y-1.5Zn-0.5Zr (wt%) alloy after a lower-temperature homogenization treatment
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金相组织%20演化%20和%20力学%20性能%20of%20a%20大尺寸%20锭%20of%20Mg-9Gd-3Y-1.5Zn-0.5Zr%20(wt%)%20合金%20后%20a%20低温%
DOI：
10.1007/s12613-017-1405-6
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发表时间：
2017-03-01
影响因子：
4.8
通讯作者：
Xu, Chao
中科院分区：
文献类型：
--
作者：
Xue, Zhi-yong;Ren, Yue-juan;Xu, Chao
本文采用半连续铸造方法成功制备了直径为600 mm的Mg-9Gd-3Y-1.5Zn-0.5Zr （wt%）合金大型铸锭。随后将合金在430℃的较低温度下退火12 h，进行均匀化处理。系统地研究了该合金的显微组织和室温力学性能。结果表明：铸态合金中含有大量由Mg10ZnY和α - mg基体组成的不连续片状18R长周期有序堆积相（LPSO），晶界处含有网状的Mg-5（Y,Gd）共晶化合物；均质化处理后，共晶化合物大部分溶解。均匀化处理后，片状LPSO相的数量和尺寸明显增加。相结构转变为组成Mg12Zn（Y,Gd）的14h型LPSO。热处理后的大尺寸合金铸锭力学性能均匀。合金的极限抗拉强度（UTS）和抗拉屈服强度（TYS）分别达到207.2 MPa和134.8 MPa，伸长率为3.4%。大尺寸合金锭经均匀化处理后的优异性能主要归因于α - mg固溶体的强化和α - mg基体上分布的丰富的LPSO相。
In this paper, a large-sized ingot of Mg-9Gd-3Y-1.5Zn-0.5Zr (wt%) alloy with a diameter of 600 mm was successfully prepared by the semi-continuous casting method. The alloy was subsequently annealed at a relatively low temperature of 430A degrees C for 12 h as a homogenization treatment. The microstructure and room-temperature mechanical properties of the alloy were investigated systematically. The results show that the as-cast alloy contained a mass of discontinuous lamellar-shaped 18R long-period stacking ordered (LPSO) phases with a composition of Mg10ZnY and an alpha-Mg matrix, along with net-shaped Mg-5(Y,Gd) eutectic compounds at the grain boundaries. Most of the eutectic compounds dissolved after the homogenization treatment. Moreover, the amount and dimensions of the lamellar-shaped LPSO phase obviously increased after the homogenization treatment. The structure of the phase transformed into 14H-type LPSO with composition Mg12Zn(Y,Gd). The mechanical properties of the heat-treated large-sized alloy ingot are uniform. The ultimate tensile strength (UTS) and tensile yield strength (TYS) of the alloy reached 207.2 MPa and 134.8 MPa, respectively, and the elongation was 3.4%. The high performances of the large-sized alloy ingot after the homogenization treatment is attributed to the strengthening of the alpha-Mg solid solution and to the plentiful LPSO phase distributed over the alpha-Mg matrix.