Characterization of mechanically milled Al65Cu 20Fe15 icosahedral quasicrystalline alloy

Abstract

Mechanical milling is a powder metallurgy processing technique capable of producing a variety of nano-crystalline and amorphous phases. In the present investigation icosahedral phase in the Al65Cu20Fe 15 system has been synthesized by slow cooling technique and mechanically milled in a high-energy attritor ball mill for 5h, 10h, 20h and 40h under hexane medium at a angular rotation speed of 400 rpm and with the powder to ball ratio of 1:40. The as cast alloys as well as milled and annealed powders have been studied by X-ray diffraction and transmission electron microscopy techniques. After 5h of mechanical milling, the evolution of disordered B2 phase has been identified. Further milling up to 10h nano-crystalline B2 phase has been observed. The microstructures in al the milled samples show typical deformation features, in particular more clearly in 40h milled sample. The isothermal heat treatment of milled powder at various temperatures establishes the transformation from disordered B2 phase to an ordered B2 phase with a grain coarsening effect.