Defect structures in FeAl B2 alloys

A Study of Point Defects in the B2-Phase Region of the Fe-Al System by Mössbauer Spectroscopy

“…According to this model, the spectrum contains four components describing different local In Table II, we present the evolution of the values of the isomer shift (IS) and quadrupole splitting (QS) of the spectra components depending on the aluminum concentration. Similar values of the IS and QS for the components describing the ordered B2 structure and the point defect were observed in theoretical calculations [20] and experimental research [7,9,13,14]. The values of vacancy and anti-site atoms concentrations found using the described model are shown in Table III.…”

“…That suggests a decrease in energy of vacancies formation in Al-rich alloys. However, the determined concentration of point defects in the samples III-V is even higher than those described in literature [3,[7][8][9]11]. This very high concentration of vacancies in the metallic powders can be related to their preparation by self-decomposition method and milling process.…”

“…The development of new, more ductile FeAl alloys depends on a thorough understanding of their properties, implicating a better comprehension of the properties and behavior of defect in these materials. Experimental as well as theoretical studies [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] suggest that point defects in iron aluminides present complex, especially triple defect structure. It is well known that upon rapid quenching from elevated temperatures, iron aluminides retain a high concentration of thermal vacancies, which frozen, increase their yield strength and hardness at room temperature [1][2][3].…”

Vacancy Formation in Fe-Al of B2 and DO3Alloys

“…It is well known that upon rapid quenching from elevated temperatures, iron aluminides retain a high concentration of thermal vacancies, which frozen, increase their yield strength and hardness at room temperature [2]. However, the technical application of these alloys is restricted presently by poor ductility at low temperatures and low fracture toughness [3][4][5][6][7][8]. Properties like creep, sintering, oxidation, and diffusion are influenced or even determined by thermal defects like vacancies.…”

“…For this reason, an exact systematic analysis of the defect formation and their characterization are decisively important for understanding of these systems. It is expected that the concentration of vacancies can be strongly changed in the aluminides with the variation of heat and mechanical treatment, together with the composition modification of the aluminides by transition metal ternary additives [5][6][7][8][9][10][11][12][13][14]. Because of its extreme sensitivity, the positron annihilation technique represents an excellent method for the study of atomic defects.…”