Au-Sn-X（X=Co，La，Er）体系的热力学优化与计算

【作者】 董红群；

【导师】 刘华山；

【作者基本信息】 中南大学 ， 材料学， 2010， 硕士

【摘要】 因其优良的延展性、完美的抗腐蚀和抗氧化能力、优异的导电、导热性能等特点,Au-20Sn被广泛的应用于光电封装、航空航天等领域。但由于Au价格昂贵,因此如何添加其他合金组元以部分替代Au,是钎料发展的方向。近年研究发现,稀土元素(RE)能改善钎料的力学性能和润湿性能,净化钎缝晶界,提高钎缝的抗疲劳强度。因此,结合我国稀土元素资源丰富的优势,研究相关体系相图,对于设计新型Au-Sn基钎料具有重要意义。本文结合现有相图实验数据及第一性原理计算的化合物形成焓,采用CALPHAD技术优化计算了Au-Co、Au-La和Au-Er三个二元体系,修正了Au-Sn和Co-Sn两个二元系；外推优化了Au-Sn-Co体系；简单外推了Au-Sn-La三元体系；且初步分别建立了各个系统的自洽的热力学数据库,取得如下主要结果：1.利用相图计算(CALPHAD)方法,采用Thermo-Calc热力学软件包优化和计算了Au-Co、Au-La和Au-Er三个二元系。其中液相与端际相采用替代溶液模型,所有中间化合物均为化学计量比型,计算所得相平衡和热力学数据均与实验数据吻合较好。2.利用第一原理计算的化合物的形成焓,结合CALPHAD方法,采用Thermo-Calc热力学软件修正了Au-Sn二元系；为更好的拟合三元相关系,微调了Sn-Co二元系热力学参数。3.利用相图计算(CALPHAD)方法,采用Pandat热力学软件包外推优化了Au-Sn-Co和简单外推了Au-Sn-La两个三元系。根据实验数据,我们发现部分化合物中第三组元的溶解度增大了,Au-Sn-Co体系中出现一个满足化学计量比的三元化合物。计算所得相图数据与实验结果一致。更多还原

【Abstract】 Due to the wonderful ductibility, excellent corrosion resistance, high electrical and heat conductivity, Au-20Sn eutectic sloder has been widely used in packaging of optoelectronic, aviation and spaceflight and so on. However, with the high price, the developing orientation of Au-Sn solder requires that the substitute be found to reduce the consumption of Au element.Recently, the reseach about substitute materials for noble elements in solder indicated that the rare earth metals can refine the mechanical performance, improve wettability, reduce the oxidization of solder, clean the grain boundary, and improve the fatigue intensity. Development of the relative phase relationship of solder is of much importance because of the abundant RE resources and its large markets.Combining the formation enthalpy of intermetallic compounds (IMCs) calculated by first principle approach with CALPHAD technique, Au-Co, Au-La and Au-Er binary systems are optimized, Au-Sn and Co-Sn binary system are modified, and Au-Sn-Co, Au-Sn-La ternary systems are calculated,1. Au-Co, Au-La and Au-Er binary systems are optimized by Thermo-Calc software using CALPHAD technique. Liquid and all the terminal solutions (Fcc, Bcc and Hcp) are modeled as substitutional solution. All the intermetallic compounds are treated as stoichemistric phases. Calculated thermodynamic data and equilibria data agree with the experiments.2. Based on the formation enthalpy of IMCs calculated by first-principle approach, the Au-Sn binary system are modified, and in order to fit well of the ternary system, the Sn-Co binary system are improved.3. Au-Sn-Co and Au-Sn-La ternary systems are calculated by Pandat software using CALPHAD technique. The solubility of ternary elements is added for some binary compounds, besides a stoichemistric ternary compound are added in Au-Sn-Co system. Calculated phase diagrams are identical with the experimental data.更多还原