Analytic modified embedded atom potentials for HCP metals
Analytic modified embedded atom potentials for HCP metals
复制标题
DOI：
10.1088/0953-8984/13/6/302
复制
发表时间：
2001-02
期刊：
影响因子：
--
通讯作者：
Wangyu Hu;Bangwei Zhang;Bai-yun Huang;F. Gao;D. Bacon
中科院分区：
文献类型：
--
作者：
Wangyu Hu;Bangwei Zhang;Bai-yun Huang;F. Gao;D. Bacon
本文对Be、Co、Hf、Mg、Re、Ru、Sc、Ti、Y和Zr等十种六角晶系金属构造了分析型修正嵌入原子方法（AMEAM）多体势。的潜力参数化使用解析函数和拟合的内聚能，非弛豫空位形成能，五个独立的二阶弹性常数和两个平衡条件。因此，每一个构造的潜力代表一个稳定的六方密堆积晶格与特定的非理想的c/a比。为了处理具有负柯西压力的金属，在总能量中加入了修正项。对于所有考虑的金属，hcp晶格被证明是能量上最稳定的fcc和bcc结构和hcp晶格与理想的c/a相比。计算了空位在这些金属中扩散的激活能。这些结果与已有的实验数据和其他作者对单空位和双空位机制的计算结果吻合得很好，并预测了最可能的扩散路径。计算了层错和表面能，其值低于典型的实验值。最后，自间隙原子（SIA）的形成能量和体积已被评估为八个可能的网站。该计算表明，基底分裂或crowdion是最稳定的配置与理想的c/a值的偏差相当大的金属和非基底哑铃（C或S）是最稳定的配置与c/a接近理想的金属。SIA的形成能与熔化温度之间的关系，除了Ru和Re外，大多数金属大致服从线性关系。
Analytic modified embedded atom method (AMEAM) type many-body potentials have been constructed for ten hcp metals: Be, Co, Hf, Mg, Re, Ru, Sc, Ti, Y and Zr. The potentials are parametrized using analytic functions and fitted to the cohesive energy, unrelaxed vacancy formation energy, five independent second-order elastic constants and two equilibrium conditions. Hence, each of the constructed potentials represents a stable hexagonal close-packed lattice with a particular non-ideal c/a ratio. In order to treat the metals with negative Cauchy pressure, a modified term has been added to the total energy. For all the metals considered, the hcp lattice is shown to be energetically most stable when compared with the fcc and bcc structure and the hcp lattice with ideal c/a. The activation energy for vacancy diffusion in these metals has been calculated. They agree well with experimental data available and those calculated by other authors for both monovacancy and divacancy mechanisms and the most possible diffusion paths are predicted. Stacking fault and surface energy have also been calculated and their values are lower than typical experimental data. Finally, the self-interstitial atom (SIA) formation energy and volume have been evaluated for eight possible sites. This calculation suggests that the basal split or crowdion is the most stable configuration for metals with a rather large deviation from the ideal c/a value and the non-basal dumbbell (C or S) is the most stable configuration for metals with c/a near ideal. The relationship between SIA formation energy and melting temperature roughly obeys a linear relation for most metals except Ru and Re.