Effects of Solid-State Reaction Synthesis Processing Parameters on Thermoelectric Properties of Mg_2Si

The Mg_(2)Si-matrix thermoelectric material was synthesized by low temperature solid-state reaction.This paper studies the effects of holding time and reaction temperature on the particle size and the properties of the material,and also studies effects of doping elemental Sb,Te and their doping seqence on the properties of the material.The result shows that excessively high temperature and elongated holding time of solid-state reaction are harmful,there is a range of particle size to ensure optimum properties and the doping sequence of Sb or Te without influencing the properties.

镁基材料中Mg_(2)Si相调控技术的研究进展

Mg_(2)Si相增强镁基材料具备低密度、高强度、高热稳定性、高耐磨性等优点,在航空航天、轨道交通等领域具备极大应用前景。研究表明,常规制备条件下Mg_(2)Si相组织粗大,有尖锐棱角,在受力过程中容易成为裂纹源而降低镁基材料的强韧性,因此需调控Mg_(2)Si相尺寸及分布。近年来,多种Mg_(2)Si相调控技术不断应用于镁基材料体系。在传统铸造方面主要通过变质处理或熔体处理调控Mg_(2)Si相形貌及尺寸,调控后初生Mg_(2)Si相由粗大枝晶状、鱼骨状转变为多面体状或颗粒状,共晶Mg_(2)Si相则由汉字状转变为细纤维状或短棒状,相尺寸也从数百微米被细化到数十微米。调控后的Mg_(2)Si相分布更加均匀,材料的强韧性也得到改善。此外,还可通过大塑性变形、快速凝固、粉末冶金等先进技术调控得到纳米级均匀弥散分布的Mg_(2)Si相增强镁基材料,材料性能也得到进一步提升。本文综述了Mg_(2)Si相形貌及分布、常规铸造过程的变质处理和熔体处理以及新兴的先进调控技术对Mg_(2)Si相增强镁基材料组织与性能影响的研究现状,还分析了不同调控技术的优势与不足,并对Mg_(2)Si相增强镁基材料未来的发展进行了展望。