Formation of AlCuFe icosahedral quasicrystal by mechanical alloying: XAFS and XRD studies

The structural evolutions of the mechanically alloyed ternary Al70Cu20Fe10 powders with the milling times and the annealing treatment were studied by X-ray diffraction (XRD) and X-ray absorption fine structure (XAFS). It was found that during the milling process, only Cu can incorporate into the lattice of Al to form an Al2Cu compound or an AlCu solid solution, depending on the milling times. However, Fe remains the original structure of bcc α-Fe. Annealing treatment at 700 °C for 4 h can drive the α-Fe to react with the Al2Cu compounds and AlCu solid solution, and the main products of the annealed Al70Cu20Fe10 (10 h) and the annealed Al70Cu20Fe10 (40 h) are the icosahedral Al65Cu20Fe15 quasicrystal and the Al(Cu, Fe) solid solution, respectively. The local structural disorders around Fe and Cu atoms in the icosahedral QC phase is about 50% larger than those of the Al(Cu, Fe) solid solution.