Formation of F- and P-Type Icosahedral Quasicrystals in the Zn–Mg–Ho Alloy System*
Formation of F- and P-Type Icosahedral Quasicrystals in the Zn–Mg–Ho Alloy System*
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Zn-Mg-Ho 合金体系中 F 型和 P 型二十面体准晶的形成*
DOI：
10.1143/jjap.37.5691
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发表时间：
1998
期刊：
影响因子：
--
通讯作者：
T. Ishimasa
中科院分区：
文献类型：
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作者：
Takayuki Shimizu;T. Ishimasa
根据 Ho 含量，Zn60Mg40-xHox 合金在 563°C 时形成两种类型的二十面体准晶：F 型和 P 型。在6≤x≤10的组成范围内，在这些合金中形成F型二十面体准晶作为主相。在 Ho 含量较低的合金中，由于 F 型有序而发生的超晶格反射强度变弱。 x=5时，形成P型二十面体准晶，并在563℃和503℃与MgZn2型Laves相共存。 P型二十面体准晶的一些电子衍射图案在与F型超晶格反射相对应的位置处表现出漫散射强度。通过在403℃下退火，P型二十面体准晶和MgZn2型相的混合物转变为F型准晶和十方准晶的混合物。前一种状态是通过在 503°C 下进行额外退火可逆地获得的。这些实验结果支持了这样的解释：三种类型的准晶体在 Zn-Mg-Ho 合金体系中形成为热力学稳定态。
Two types of icosahedral quasicrystals, F- and P-types, formed at 563°C in the Zn60Mg40-xHox alloy depending on Ho content. In the composition range of 6≦x≦10, F-type icosahedral quasicrystal formed as a major phase in these alloys. The intensity of superlattice reflections which occurred due to F-type ordering became weaker in the alloys with lower Ho content. At x=5, P-type icosahedral quasicrystal formed, coexisting with MgZn2-type Laves phase at 563°C and 503°C. Some electron diffraction patterns of the P-type icosahedral quasicrystal exhibited diffuse scattering intensity at positions corresponding to F-type superlattice reflections. By annealing at 403°C, a mixture of the P-type icosahedral quasicrystal and the MgZn2-type phase changed to a mixture of the F-type quasicrystal and a decagonal quasicrystal. The former state was reversibly obtained by additional annealing at 503°C. These experimental results support the interpretation that the three types of quasicrystals form as a thermodynamically stable state in the Zn–Mg–Ho alloy system.