Pre-peak on the structure factor of liquid hypoeutectic Al-Fe alloy

作     者：Jingyu Qin Xiufang Bian Weimin Wang Jiaji Ma Changye Xu 

作者机构：Shandong Univ Technol Coll Mat Sci & Engn Jinan 250061 Peoples R China Shandong Univ Technol Dept Math & Phys Jinan 250061 Peoples R China 

出 版 物：《Chinese Science Bulletin》 (中国科学通报)

年 卷 期：1998年第43卷第14期

页      面：1219-1224页

核心收录：

学科分类：08[工学] 080502[工学-材料学] 0805[工学-材料科学与工程（可授工学、理学学位）] 

基　　金：theNationalNaturalScienceFoundationofChina (GrantNo .5 96 710 4 6 ) 

主　　题：liquid hypoeutectic Al Fe alloy structure factor pre peak X ray diffraction. 

摘      要：Using a θ-θ X ray diffractometer the structure of liquid hypoeutectic Al Fe alloy at 675℃ and its change with different thermal histories are investigated . Liquid Al is used as a reference system. It is found that a pre peak appears on the small angle part of the structure factor of the nonsuperheated hypoeutectic Al Fe alloy, but disappears after superheating whereas the structure factors of liquid Al hardly change with the different thermal histories, and no pre peak can be observed on them. The appearance of a pre peak is a mark of the intermediate range order (IRO). The pre peak is taken as the correlation between Fe atoms on the IRO length scale. Assume that the crystalline structure is the first order approximation of the liquid structure. A model structure is constructed. The basic unit is a cube formed by 8 Al atoms on its corner and one Fe atom occupying its center. The translation of such a unit along its fourbody diagonals by the length of a diagonal can meet the requirement of the Fe_Fe distance and gives a DO 3 like structure. If the vacancy among the units is filled with fcc like Al cells, the composition of the entity is about Al 7Fe, close to that of the metastable phase Al 6Fe from rapid solidification. It is speculated that there are Al 6Fe like clusters in the liquid hypoeutectic Al Fe alloy.