高温度梯度定向凝固单相Mg2Sn合金的制备及其热电性能  

Preparation and Thermoelectric Properties of Single-phase MgSn Alloys by High Temperature-gradient Directional Solidification

作　　者：李鑫[1] 谢辉[1] 张亚龙 魏鑫 Li Xin;Xie Hui;Zhang Yalong;Wei Xin(Xi’an Aeronautical University,Xi’an 710077,China)

机构地区：[1]西安航空学院,陕西西安710077

出　　处：《稀有金属材料与工程》2020年第7期2436-2443,共8页Rare Metal Materials and Engineering

基　　金：国家自然科学基金青年项目(51904219);西安航空学院校级科研基金(2019KY0203)。

摘　　要：高温度梯度(180K/cm)定向凝固方法可制备单相Mg2Sn晶体,通过凝固理论对平-胞转换临界速率进行了计算,并预测了单相Mg2Sn晶体的生长距离,与试验结果相吻合。此方法获得的Mg2Sn晶体由于去除了第二相Sn的影响,可以获得更好的热电性能,在测试温度区间300~700K内,未掺杂条件下最大Seebeck系数和电导率值分别可达-261μV·K-1和525Ω-1·m^-1,通过Bi掺杂来对电导率进行优化后,功率因子最高可达2.29 mW·(m·K^2)-1。单相Mg2Sn晶体的热导率也得到大幅降低,500 K时,最小值为4.3 W·(m·K)^-1,Bi掺杂量为1.5%(原子分数)时,热电优值ZT最高可达到0.21。这一方法可以为制备高性能的Mg2BIV体系三元固溶体合金提供参考。Single-phase Mg2Sn crystal was directionally solidified from the melt with a high temperature gradient of 180 K/cm.The critical velocity of planar interface and solidified distance for the growth of single-phase Mg2Sn crystal was predicted theoretically and it agrees well with the experimental result.The grown Mg2Sn crystals exhibit better thermoelectric performance without influence of the second phase Sn.At the temperature ranging from 300 K to 700 K,the maximum Seebeck coefficient S and electrical conductivityσreach–261μV·K-1 and 525Ω-1·m^-1,respectively.The top value of power factor is 2.29 mW·(m·K^2)-1 after the doped Bi optimization.The minimum thermal conductivityκis measured as 4.3 W·(m·K)-1 at T=500 K.The maximum value of merit ZT is 0.21 at the doping concentration of 1.5%Bi.The method developed in this paper can provide a methodological reference for the preparation of ternary Mg2BIV solid solution.

关 键 词：晶体生长 高温度梯度定向凝固 热电性能 Mg2Sn 

分 类 号：TG146.22[一般工业技术—材料科学与工程] O782[金属学及工艺—金属材料]