Synthesis of $$\hbox {Fe}_{3}$$ Fe 3 Al Intermetallic Compound by Mechanical Alloying

Abstract

In the present work, nanostructured $$\hbox {Fe}_{3}\hbox {Al}$$ intermetallic compound has been synthesized by mechanical alloying (MA) of $$\hbox {Fe}_{75}\hbox {Al}_{25}$$ powder milled for 40 h followed by heat treatment at $$1100\,{^{\circ}}\hbox {C}$$ for 2 h in Ar atmosphere. The structural evolution of the $$\hbox {Fe}_{75}\hbox {Al}_{25}$$ powder during MA and subsequent isothermal annealing was analyzed using X-ray diffraction (XRD). After 40 h of milling, a disordered Fe(Al) solid solution is formed. On annealing, the Fe(Al) solid solution undergoes an ordering transformation resulting in the formation of ordered $$\hbox {D0}_{3}$$ - $$\hbox {Fe}_{3}\hbox {Al}$$ . The presence of the (111) superlattice peak in the XRD plot of the annealed powder is a direct evidence of the ordered arrangements in the alloy. A shallow exothermic peak below $$600\,{^{\circ}}\hbox {C}$$ in the DSC plot of the 40-h milled powder also confirms the formation of ordered $$\hbox {D0}_{3}$$ - $$\hbox {Fe}_{3}\hbox {Al}$$ . The EDX analysis of the $$\hbox {Fe}_{75}\hbox {Al}_{25}$$ powder milled for various periods of time confirmed the gradual increase in Al diffusion in the Fe particles. The diffusion process of Al in Fe was analyzed using the elemental maps of Fe and Al in the $$\hbox {Fe}_{75}\hbox {Al}_{25}$$ powder milled for various periods of time. HRTEM images confirmed that the $$\hbox {Fe}_{3}\hbox {Al}$$ synthesized by MA is <15 nm in size.