Samolyuk G D, Béland L K, Stocks G M, Stoller R E
Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
J Phys Condens Matter. 2016 May 5;28(17):175501. doi: 10.1088/0953-8984/28/17/175501. Epub 2016 Apr 1.
Energy transfer between lattice atoms and electrons is an important channel of energy dissipation during displacement cascade evolution in irradiated materials. On the assumption of small atomic displacements, the intensity of this transfer is controlled by the strength of electron-phonon (el-ph) coupling. The el-ph coupling in concentrated Ni-based alloys was calculated using electronic structure results obtained within the coherent potential approximation. It was found that Ni0.5Fe0.5, Ni0.5Co0.5 and Ni0.5Pd0.5 are ordered ferromagnetically, whereas Ni0.5Cr0.5 is nonmagnetic. Since the magnetism in these alloys has a Stoner-type origin, the magnetic ordering is accompanied by a decrease of electronic density of states at the Fermi level, which in turn reduces the el-ph coupling. Thus, the el-ph coupling values for all alloys are approximately 50% smaller in the magnetic state than for the same alloy in a nonmagnetic state. As the temperature increases, the calculated coupling initially increases. After passing the Curie temperature, the coupling decreases. The rate of decrease is controlled by the shape of the density of states above the Fermi level. Introducing a two-temperature model based on these parameters in 10 keV molecular dynamics cascade simulation increases defect production by 10-20% in the alloys under consideration.
在辐照材料的位移级联演化过程中，晶格原子与电子之间的能量转移是能量耗散的一个重要通道。在小原子位移的假设下，这种转移的强度由电子 - 声子（el - ph）耦合强度控制。利用在相干势近似下获得的电子结构结果计算了浓镍基合金中的el - ph耦合。发现Ni0.5Fe0.5、Ni0.5Co0.5和Ni0.5Pd0.5呈铁磁有序，而Ni0.5Cr0.5是非磁性的。由于这些合金中的磁性具有斯托纳型起源，磁有序伴随着费米能级处电子态密度的降低，这反过来又降低了el - ph耦合。因此，所有合金在磁性状态下的el - ph耦合值比非磁性状态下的同一合金大约小50%。随着温度升高，计算得到的耦合最初会增加。超过居里温度后，耦合减小。减小速率由费米能级以上的态密度形状控制。在10 keV分子动力学级联模拟中基于这些参数引入双温模型，在所考虑的合金中使缺陷产生增加了10% - 20%。
