Ni-Si共晶的标准生成焓估算及晶体生长机理研究

Estimation of Standard Enthalpy of Ni-Si Eutectic Alloy and Study on Crystal Growth Mechanism

对采用布里奇曼定向凝固技术制备的Ni-Si共晶复合材料的晶体生长机理进行了研究。结果表明,在初始过渡区形成的是较粗大的金属间化合物和α-Ni基体。在稳态晶体生长区,形成了α-Ni、Ni_3Si、Ni_31Si_(12)三相。在分析已有的热力学数据基础上,采用双参数模型,并通过模型求解,估算了二元金属化合物Ni_3Si、Ni_31Si_(12)的标准生成焓,并从热力学角度,探索了亚稳相的形成机理。

The crystal growth mechanism of Ni-Si eutectic in-situ composite produced by bridgman directional solidification technique was studied. The results show that the coarse intermetallic compound and α-Ni matrix can be obtained in the primary transion zone. The α-Ni, Ni3Si and Ni31Si12 phases can be obtained in stable crystal growth zone. Based the analysis of existing thermodynamic data, a two-parameter model for estimating the standard enthalpy of dual intermetallic was adopted to calculate the standard enthalpies of Ni3Si and Ni31Si12 phase. Moreover, the formation mechanism of metastable phase was researched from the viewpoint of the thermo-dynamics.