Thermodynamic analysis of the compounds in heat resistant steels based on the CALPHAD method

本文用CALPHAD方法计算了高铬铁素体钢中各相的吉布斯自由能函数。在基态的MX和Z相的形成焓估计从从头计算在各种组合的过渡元素从3a到3b组。在这些化合物中，含有Ta-、Sc-、V-族元素的Z相具有很低的生成焓.这表明它们是非常稳定的，因此这些Z相可以用作高Cr铁素体钢的强化因子，而不是细分散的MX相。计算的相平衡与工业合金（T91）的实验数据符合得很好。通过NIMS热力学数据库网站，对各相的吉布斯自由能函数进行了公开。可从网站下载数据库文件并复制当前结果。

The Gibbs energy functions of the phases in the high-Cr ferritic steels have been assessed thermodynamically using the CALPHAD method. Formation enthalpy of the MX and Z phases at the ground state were estimated from ab initio calculations in various combinations of transition elements from 3a to 3b groups. Of the combinations, the Z phase with Ta-, Sc-, V- group elements exhibited very low formation enthalpy. This suggests that they are significantly stable; thus these Z phases can be used as a strengthening factor of the high-Cr ferritic steels instead of the fine dispersed MX phases. The calculated phase equilibria are in good agreement with experimental data of the commercial ally (T91). The assessed Gibbs energy functions of the phases have been opened for public through the website named "NIMS thermodynamic database". From the website, the database files can be downloaded and reproduce the present results.