Phonon dispersion curves for ordered, partially-ordered and disordered iron-aluminium alloys
Phonon dispersion curves for ordered, partially-ordered and disordered iron-aluminium alloys
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DOI：
10.1088/0953-8984/3/42/013
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发表时间：
1991-10
期刊：
影响因子：
--
通讯作者：
I. Robertson
中科院分区：
文献类型：
--
作者：
I. Robertson
用中子非弹性散射法测定了铁铝合金在高对称方向上的声子色散曲线。该合金的成分接近25原子%的铝，并在有序的BCC，B2和D 03结构的三种状态下制备。通过拟合第六近邻Born-von Karman模型对数据进行分析。声子频率遵循BCC到B2到D 03的排序顺序中的一致趋势。类似的趋势在最近邻原子的力常数值中也很明显，但在较远邻原子的力常数值中则不那么明显。在低频模式中，软（qq 0）横模对原子力常数的变化最敏感。由于铁和铝原子质量的巨大差异以及力常数的变化，高频模式由于有序化而表现出频率的巨大变化。
Neutron inelastic scattering determination of the phonon dispersion curves in high symmetry directions for iron-aluminium alloys are presented. The alloys have compositions near 25 atomic percent aluminium, and were prepared in three states of ordered BCC, B2 and D03 structures. The data were analysed by fitting sixth-nearest neighbour Born-von Karman models. The phonon frequencies follow a consistent trend in the ordering sequence BCC to B2 to D03. A similar trend is apparent in the values of the atomic force constants for the nearest neighbours but is less apparent for the force constants for more distant neighbours. Of the low frequency modes, the soft (qq0) transverse mode is the most sensitive to changes in the atomic force constants. High frequency modes exhibit large changes in frequency as a result of ordering because of the large difference in the masses of iron and aluminium atoms, as well as the changes in force constants.