LPSO相增强铸态Mg_(92)Zn_4Y_4和Mg_(92)Zn_4Y_3Gd_1合金组织与性能分析（英文）

Microstructures and Properties of As-Cast Mg_(92)Zn_4Y_4 and Mg_(92)Zn_4Y_3Gd_1 Alloys with LPSO Phase

采用普通凝固技术制备了含有长周期堆垛有序(long period stacking ordered,LPSO)结构相的Mg92Zn4Y4和Mg92Zn4Y3Gd1合金。通过OM、SEM、EDS、XRD和TEM分析了合金中各相形貌、微区成分及结构。结果表明:Zn/RE原子比为1的2种铸态镁合金中均存在14H-LPSO结构相;在Mg-Zn-Y合金中添加稀土元素Gd增加了合金的形核质点并促进了长周期堆垛有序结构相的形成,14H-LPSO相体积分数由12.1%增至30.4%;LPSO结构相在高温形成时分割了αMg树枝晶,基体平均晶粒尺寸由50μm降至10μm以下;铸态Mg92Zn4Y4合金的凝固组织为α-Mg固溶体+Mg12Zn Y+Mg3Zn3Y2+Mg-Y;铸态Mg92Zn4Y3Gd1合金的凝固组织主要为α-Mg固溶体+Mg12Zn(Y,Gd)+Mg3Zn3(Y,Gd)2;室温条件下,Mg92Zn4Y4和Mg92Zn4Y3Gd1合金的压缩率达到12.4%和15.5%,热导率分别为99.233和88.639W·(m·K)-1。

Mg92Zn4Y4 and Mg92Zn4Y3Gd1 alloys with long period stacking ordered（LPSO） structure phases were prepared by conventional solidification process.By OM, SEM, EDS, XRD and TEM analysis the phases and 14H-LPSO structures of the two alloys were characterized.The results show that as-cast Mg-alloy with the atomic ratio of Zn/RE = 1 will lead to LPSO phase; adding of Gd element to Mg92Zn4Y4 alloy can facilitate the formation of LPSO phase, and its volume fraction increases from 12.1% to 30.4%; Mg dendrites are split and refined during the precipitation of LPSO phase formed at high temperature, resulting in that the average grain size of α-Mg decreases from 50 μm to 10 μm; the solidification microstructure of as-cast Mg92Zn4Y4 alloy is α-Mg solid solution ＋ Mg12 Zn Y ＋ Mg3Zn3Y2 ＋ Mg-Y; In Mg92Zn4Y3Gd1 alloy, the as-cast microstructure is confirmed to be composed mainly of α-Mg solid solution, Mg12Zn（Y, Gd） and Mg3Zn3（Y, Gd）2; at room temperature, the compression ratio and the thermal conductivity of Mg92Zn4Y4 and Mg92Zn4Y3Gd1 alloys are 12.4% and 15.5%, and 99.233 W·（m·K）^-1 and 88.639 W·（m·K）^-1, respectively.