机械合金化Fe30Cu70二元体系的局域结构研究

利用XAFS和XRD技术，研究机械合金化方法制备的Fe30Cu70二元体系的局域环境结构随球磨时间的变化，当球料比为40：1时，球磨5h,XRD结果表明，bcc结果αFe相的衍射峰几乎消失，只有fcc结构Fe30Cu70合金相的衍射峰存在，随着球磨时间的增加，fcc结构Fe30Cu70合金相的晶格略有膨胀，且晶格参数逐渐增大，XAFS结果显示：在机械合金化过程中，Fe30Cu70样品的Fe原子的近邻结构与Cu原子的近邻结构有不同的变化规律，Cu原子周围的局域晶格结构受球影响不大，但Fe原子周围的局域晶格结构形变较大，其无序度随时间增加而明显增大，所以，机械球磨后形成的Fe30Cu70合金并不是组成均匀的过饱和固溶体，其中既有Cu原子浓度大于化学计量比的fcc结构Cu富集区，又有Fe原子浓度大于化学计量比的Fcc结构Fe的富集区。

Local Structures of Mechanically Alloyed Fe_( 30) Cu_(70) Binary System Studied by XAFS and XRD

XAFS and XRD have ben used to investigate the local structure ofthe Fe30Cu70 alloy produced by mechanical aloying (MA). The XRD result shows that the diffraction peak of bcc α-Fe phase nearly disappears and the diffraction peak of fcc structure remains after Fe and Cu mixture has been milled 5 hours at the condition of the weight ration of the ball to powder (40:1). With the increase of milling time, the lattice of Fe30Cu70 alloy gradually expands. The XAFS result further indicates that there is a big difference in the local structure between Fe and Cu atoms for Fe30Cu70 solid solutions during the MA process. The disorder degree of Fe atoms rises with the increase of the milling time while the Cu atoms remain the same as that of the initial sample. It is considered that the MA Fe70Cu30 alloy is not a homogeneous supersaturated solid solution, but consists of fcc Cu-rich and fcc Fe-rich regions.