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

Abstract

The structural evolutions of the mechanically alloyed ternary Al 70Cu 20Fe 10 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 Al 2Cu 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 Al 2Cu compounds and AlCu solid solution, and the main products of the annealed Al 70Cu 20Fe 10 (10 h) and the annealed Al 70Cu 20Fe 10 (40 h) are the icosahedral Al 65Cu 20Fe 15 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.