Lattice Vibrations Change the Solid Solubility of an Alloy at High Temperatures.
Lattice Vibrations Change the Solid Solubility of an Alloy at High Temperatures.
复制标题
DOI：
10.1103/physrevlett.117.205502
复制
发表时间：
2015-03
影响因子：
8.6
通讯作者：
N. Shulumba;O. Hellman;Z. Raza;B. Alling;J. Barrirero;F. Mücklich;I. Abrikosov;M. Odén
中科院分区：
文献类型：
--
作者：
N. Shulumba;O. Hellman;Z. Raza;B. Alling;J. Barrirero;F. Mücklich;I. Abrikosov;M. Odén
我们开发了一种方法，以准确和有效地确定作为温度和体积的函数的替代合金的第一性原理的振动自由能。以Ti_{1-x}Al_{x}N合金为模型体系，通过寻找体系真实平衡态所对应的自由能的全局极小值，计算出了等结构相图。结果表明，非谐振动和混合焓的温度依赖性对Ti_{1-x}Al_{x}N合金相图的计算结果有决定性影响，使合金的最大相容性能隙温度从6560 K降低到2860 K.热时效Ti_{0.5}Al_{0.5}N合金的局部化学成分测量结果与计算相图相吻合。
We develop a method to accurately and efficiently determine the vibrational free energy as a function of temperature and volume for substitutional alloys from first principles. Taking Ti_{1-x}Al_{x}N alloy as a model system, we calculate the isostructural phase diagram by finding the global minimum of the free energy corresponding to the true equilibrium state of the system. We demonstrate that the vibrational contribution including anharmonicity and temperature dependence of the mixing enthalpy have a decisive impact on the calculated phase diagram of a Ti_{1-x}Al_{x}N alloy, lowering the maximum temperature for the miscibility gap from 6560 to 2860 K. Our local chemical composition measurements on thermally aged Ti_{0.5}Al_{0.5}N alloys agree with the calculated phase diagram.