Microstructural and kinetic aspects of the transformations induced in a FeAl alloy by ball-milling and thermal treatments

• Published in: Acta materialia Vol. 46; no. 9; pp. 3305 - 3316
• Main Authors: Gialanella, S., Amils, X., Barò, M.D., Delcroix, P., Le Caër, G., Lutterotti, L., Suriñach, S.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 22-05-1998; Elsevier Science
• Subjects: Applied sciences; Exact sciences and technology; Metals. Metallurgy; Powder metallurgy. Composite materials; Production techniques; Sintered metals and alloys. Pseudo alloys. Cermets; Ball mill; Metal powder; Intermetallic compound; Moessbauer spectrometry; Aluminium alloy; Experimental study; Powder metallurgy; X ray diffraction; Structure processing relationship; Phase transformation; Solid state reaction; Kinetics; Microstructure; Iron base alloys; Binary alloy
• ISSN: 1359-6454; 1873-2453
• DOI: 10.1016/S1359-6454(97)00484-9

A Fe–40Al (at.%) alloy powder having a B2 ordered structure was milled in a high energy planetary ball-mill. The microstructural evolution of the alloy was followed by analysing powder specimens milled for different times by X-ray diffraction, Mössbauer spectroscopy and magnetisation measurements. Grain refinement and chemical disordering were the main transformations resulting from milling. A complete destruction of the long-range order under the adopted conditions of milling was not achieved. From diffraction analyses it was possible to see how the concentrations of such defects as dislocations, planar faults, antiphase domain boundaries, etc., were modified by the heavy deformations involved with milling. Starting from the specimens milled for the longest time, considered in this study, isothermal annealing experiments were carried out to monitor the reverse transformations. The annealing temperatures were selected on the basis of differential scanning calorimetric and thermogravimetric magnetic measurements, which revealed that several transformations occur when treating the deformed powders. Recovery and reordering take place at temperatures ranging from 100 up to 250°C. A complete reordering is possible only at higher temperatures, i.e. 700°C, when recrystallisation is fully accomplished.