Advanced Powder Technology, Vol.25, No.5, 1483-1491, 2014
Nanocrystalline Al/Al-12(Fe,V)(3)Si alloy prepared by mechanical alloying: Synthesis and thermodynamic analysis
Al-Al-12(Fe,V)(3)Si nanocrystalline alloy was fabricated by mechanical alloying (MA) of Al-11.6Fe-1.3V-2.3Si (wt.%) powder mixture followed by a suitable subsequent annealing process. Structural changes of powder particles during the MA were investigated by X-ray diffraction (XRD). Microstructure of powder particles were characterized using scanning electron microscopy (SEM). Differential scanning calorimeter (DSC) was used to study thermal behavior of the as-milled product. A thermodynamic analysis of the process was performed using the extended Miedema model. This analysis showed that in the Al-11.6Fe-1.3V-2.3Si powder mixture, the thermodynamic driving force for solid solution formation is greater than that for amorphous phase formation. XRD results showed that no intermetallic phase is formed by MA alone. Microstructure of the powder after 60 h of MA consisted of a nanostructured Al-based solid solution, with a crystallite size of 19 nm. After annealing of the as-milled powder at 550 degrees C for 30 min, the Al-12(Fe,V)(3)(S)i intermetallic phase precipitated in the Al matrix. The final alloy obtained by MA and subsequent annealing had a crystallite size of 49 nm and showed a high microhardness value of 249 HV which is higher than that reported for similar alloy obtained by melt spinning and subsequent milling. (C) 2014 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.