极端条件下锆的动力学稳定性研究

Dynamic stability of Zr under high pressure and high temperature

过渡金属Zr具有优良的物理、化学及力学性能,具有广泛的应用价值.主要通过新近发展的自洽晶格动力学方法,充分考虑声子间的相互作用,成功获得了β-Zr的高温高压声子色散曲线,预测了β-Zr在相图中能够稳定存在的区域,进一步比较α-Zr,ω-Zr和β-Zr的自由能,获得了α-β及ω-β相变的相边界,构建了Zr的参考相图.同时,也获得了β-Zr的高温状态方程及热膨胀系数,能够为构建Zr的全区物态方程提供有益的参考.

The phase transitions and structure stabilities of materials have always attracted much attention of the experimental and theoretical investigators. ＇When calculating the phonon dispersion of the cubic structure of the transition metal Zr （β-Zr）, the traditional methods always give the negative phonon frequencies. So the quasi-harmonic approximation cannot solve this kind of problem. We obtain the phonon dispersion of β-Zr at high pressure and high temperature by using the newly developed self-consistent ab initio lattice dynamics method, which can well consider the phonon-phonon interactions. And then the stable region of β-Zr in the high pressure and high temperature phase diagram is predicted. The full phase diagram of Zr is also predicted. We also obtain the high temperature equation of state （EOS） and thermal expansion of β-Zr, which can help to construct the EOS data base of Zr.