铁基非晶态因瓦合金的热中子散射研究

THERMAL NEUTRON SCATTERING ON Fe BASED AMORPHOUS INVAR ALLOYS

因瓦（ｌｎｖａｒ）合金具有热膨胀性能随温度变化反常的特性，很多非晶态合金也具有显著的因瓦效应。用中子非弹性散射方法测量了铁基非晶态金属－金属型Ｆｅ９０－ｘＣｏｘＺｒ１０（ｘ＝１０，４０）和金属－类金属型Ｆｅ８０－ｙＣｒｙＰ１３Ｃ７（ｙ＝４，８）合金，以及Ｆｅ８６Ｃｏ４Ｚｒ１０因瓦合金居里点（ＴＣ＝３３０Ｋ）上下的广义声子谱。从３组声子谱的比较中，观察到了与因瓦效应相关的声子软化现象。结合已经观察到的晶态因瓦合金的声子软化现象，认为声子软化现象是因瓦效应的基本特征之一，它与晶格的长程有序无关，与材料类型无关。

Invar alloys are characterized by an anomalous small thermal expansion coefficient.Many amorphous alloys also exhibit obvious Invar effect. Generalized phonon spectra for Fe based amorphous metal metal Fe 90- x Co x Zr 10 ( x =10,40)and metal metalleid Fe 80- y Cr y P 13 C 7 ( y =4,8) alloys,and Fe 86 Co 4Zr 10 Invar alloy at different temperatures above and below the Curie temperature ( T C=330 K) are measured using neutron inelastic scattering method.According to comparisons on corresponding three phonon spectra,the phonon softening related with Invar effect are observed.This result is quite similar to the acoustic phonon softening of the crystalline Invar alloy,indicating that low energy phonon softening is a common feature of Invar alloys. It is irrelevant to the long range order of crystalline and the type of materials. It is suggested that the phonon softening in Invar alloys could be attributed to an enhancement of the electron phonon interaction.