机械合金化AlCuFe形成准晶体的XAFS定量分析

Quantitative studies on formation of mechanically alloyed AlCuFe quasicrystal by XAFS

为了准确辨别AlCuFe准晶体(QC)形成的相变过程,进而探索其形成机理,采用X射线吸收精细结构(XAFS)定量分析技术,计算不同球磨时间Al70Cu20Fe10合金中的Cu原子,以及700℃退火后的Cu和Fe原子的局域结构参数,并与X射线衍射(XRD)分析进行比对。结果表明,经过不同球磨时间,样品中Al和Cu首先形成Al2Cu金属间化合物,进而转化为Cu9Al4,Fe原子仍然是原来的体心立方(bcc)α-Fe结构。α-Fe与Al和Al2Cu经过退火处理化合为Al7Cu2Fe化合物,进而转变为QC;而长时间球磨产生的Cu9Al4退火后化合为稳定的Al(Cu,Fe)固溶体,不会形成QC。

To exactly identify the structural evolutions of the solid-state reactions taking place in the milling and subsequent annealing at 700 degree,which depict the mechanism of quasicrystal （QC） formation,the quantitative analysis using X-ray absorption fine structure （XAFS） was performed.The local structure data of Fe and Cu are in good agreement with the X-ray diffraction （XRD） analysis.The results indicate that during the milling process,only Cu can incorporate into the lattice of Al to form Al2Cu and Cu9 Al4 successively.Fe remains the original structure of bcc α-Fe.The annealing can drive the α-Fe to react with Al and Al2Cu to form Al7Cu2Fe compound.Then at higher temperature the Al7 Cu2Fe transformed into QC,and Cu9Al4 is combined into stable Al（Cu,Fe） solid solution,respectively Al（Cu,Fe） can inhibit the formation of QC once it forms.