Ce-Zr基合金液-液相分离机制及双相块体非晶合金研究

Liquid-liquid phase separation and two-phase bulk metallic glasses of Ce-Zr based alloys

单一均匀的Ce-Zr二元合金熔体在冷却过程中发生液-液相分离,形成富Ce和富Zr两液相.当Ce-Zr合金中添加元素Cu和Co时, Cu与Co分别富集在富Ce和富Zr液相中,形成富Ce-Cu和富Zr-Co两液相.富Ce-Cu和富Zr-Co两共存液相的化学成分与温度相关.在冷却过程中,两分离液相的双非晶形成能力随温度而变化.本文研究了Cu和Co合金元素在Ce-Zr二元液-液分离体系中的偏聚行为;考察了Al元素对富Ce-Cu和富Zr-Co两液相的双非晶形成能力的影响.结果表明,元素Al在两分离液相中的浓度相当,而且Al元素可同时促进富Ce-Cu和富Zr-Co两液相的非晶形成能力.在此基础上,对比分析了富Ce-Cu-Al和富Zr-Co-Al两液相各自非晶形成能力,建立了通过化学性质相似混合稀土RE部分替代Ce来提高两液相双非晶形成能力的方法,并探索了稀土基双相块体非晶合金的力学性能.

The binary Ce-Zr system is characterized by a liquid-state miscibility gap. The single-phase Ce-Zr alloy melt separates into Zr-rich and Ce-rich liquids upon cooled in the miscibility gap. When the elements Cu and Co are added into the binary alloy, the liquid-liquid phase separation into Zr-Co-rich and Ce-Cu-rich liquids takes place. The glass-forming ability of Zr-Co-rich and Ce-Cu-rich liquids changes with the melt temperature because the chemical compositions of the two-coexistence liquids are related to the temperature. In this work, the segregation behavior of the addition elements Cu and Co in the binary Ce-Zr system has been studied. The effect of element Al on two-glass-forming ability of the Zr-Co-rich and Ce-Cu-rich liquids is investigated. The results show that the concentrations of element Al in two separated liquids are almost equal and the element Al can enhance the glass-forming ability of both Zr-Co-rich and Ce-Cu-rich liquids. Based on the comparison of the glass-forming ability of the Zr-Co-Al-rich and Ce-Cu-Al-rich liquids, a strategy of partial substitution by similar rare earth elements to enhance the two-glass-forming ability has been proposed.The mechanical properties of the two-phase bulk metallic glasses with the Zr-rich glassy particles embedded in the RE-rich glassy matrix have been explored.