THE STUDY OF Al-Fe BASED ALLOYS BY MECHANICAL ALLOYING

Mechancal alloying(MA) is a ball milling process where pure element powders or mixture powders placed in the ball mill is subjected to high energy collision,milling from the balls and solid state reaction takes place. For pure element powders, this process is also called Mechanical Milling(MM) or Mechanical Grinding (MG).Up to now, MA is the most economic way to manufacture materials among all the way. The technology has been used to prepare dispersion strengthening, supersaturated solid solution, intermetallic compound, quasicrystalline, nanocrystalline materials and functional materials such as magnetism, superconductor.This paper studied mechanical alloying of binary alloys Al,.xFex(x=0.05> 0.25s 0.5> 0.75) by virtue of X-Ray diffraction (XRD), scanning electron microscopy (SEM) and differential scaning calorimetry(DSC). During the ball milling of Al-25at%Fe mixture powders, Al soluted into Fe firstly, then formed Fe(Al) solid solution and amorphous phase, Fe(AI)solid solution and amorphous phase transformed into AI5Fe2 intermetallic compound in the end as the increment of the ball milling time. The nanometer scale intermetallic compound Al5Fe2 phase was obtained by mechanical alloying. During the process of heat treating for the Al-25at%Fe mixture powders ball milled for 75,100,130h respectively, all of Fe(Al) solid solution, amorphous phase and metastable Al5Fe2 phase transformed into AlsFe2 phase with regular crystal lattice.Metal Ti-substitution for Fe or Al in the Al-25at%Fe mixture powders were ball milled. Ti addition shortened the milling time of Al soluting into Fe and the formation of Fe(AI,Ti) solid solution. Also, Ti addition shortened the milling time of the formation of nanometer scale AI5Fc2 phase. Amorphous phase could be obtained by ball milling of Al-Fe-Ti ternary alloys.Nonmetal B-substitution for Fe or Al in the Al-25at%Fe mixture powders were ball milled, too. B addition accelerated the fining of the powders' partical size, shortened the milling time of the formation of nanometer scale Al5Fe2 crystalline. When the content of B was among a suitable range, B addition could accelerate the formation of amorphous phase.