A Review on the Properties of Iron Aluminide Intermetallics

Abstract

Iron aluminides have been among the most studied intermetallics since the 1930s, when their excellent oxidation resistance was first noticed. Their low cost of production, low density, high strength-to-weight ratios, good wear resistance, ease of fabrication and resistance to high temperature oxidation and sulfurization make them very attractive as a substitute for routine stainless steel in industrial applications. Furthermore, iron aluminides allow for the conservation of less accessible and expensive elements such as nickel and molybdenum. These advantages have led to the consideration of many applications, such as brake disks for windmills and trucks, filtration systems in refineries and fossil power plants, transfer rolls for hot-rolled steel strips, and ethylene crackers and air deflectors for burning high-sulfur coal. A wide application for iron aluminides in industry strictly depends on the fundamental understanding of the influence of (i) alloy composition; (ii) microstructure; and (iii) number (type) of defects on the thermo-mechanical properties. Additionally, environmental degradation of the alloys, consisting of hydrogen embrittlement, anodic or cathodic dissolution, localized corrosion and oxidation resistance, in different environments should be well known. Recently, some progress in the development of new micro-and nano-mechanical testing methods in addition to the fabrication techniques of micro-and nano-scaled samples has enabled scientists to resolve more clearly the effects of alloying elements, environmental items and crystal structure on the deformation behavior of alloys. In this paper, we will review the extensive work which has been done during the last decades to address each of the points mentioned above.

Effect of aluminizing and oxidation on the thermal fatigue damage of hot work tool steels for high pressure die casting applications

“…First, the microstructure of the initial intermetallic coating evolved to a complex multilayered intermetallic and oxide, due to the thermally activated diffusion of iron, aluminium and oxygen at high temperature. The new phases identified in this multilayer were in agreement with the Fe-Al equilibrium diagram and the literature [48][49][50][51]. Then, the micro-cracks propagated through the modified intermetallic layer both toward the steel (in depth) and along "zz" axis (on the surface), as observed in the compact oxide scale formed on virgin specimens tested in air.…”

Effect of Nickel and Titanium on Properties of Fe-Al-Si Alloy Prepared by Mechanical Alloying and Spark Plasma Sintering

“…This effect is caused by the formation of protective layer of aluminum oxide, as reported later [2]. In an Fe-Al system, a series of intermetallics have been described, namely Fe 3 Al, FeAl, Fe 2 Al 5 and FeAl 3 (also mentioned as Al 13 Fe 4 ) [2][3][4]. The first two ones, which are in fact ordered solid solutions, have gained technical importance.…”

“…Iron-aluminum alloys have been investigated since 1894, when the positive effect of aluminum addition on the high-temperature oxidation of iron was reported [1]. This effect is caused by the formation of protective layer of aluminum oxide, as reported later [2]. In an Fe-Al system, a series of intermetallics have been described, namely Fe 3 Al, FeAl, Fe 2 Al 5 and FeAl 3 (also mentioned as Al 13 Fe 4 ) [2][3][4].…”

Design, fabrication and characterization of FeAl-based metallic-intermetallic laminate (MIL) composites

“…where is an empirical number sensitive to the material [31], is the Taylor factor which is a constant, is shear modulus, is the solute concentration and is the misfit parameter, which relates to modulus and atomic size difference. The strengthening effect in intermetallics is more complicated as short-range order, vacancies and other factors need to be taken into consideration [23]. The values collected from the pure iron region of the Fe-FeAl MIL composite are slightly higher than the reference pure Fe foils, but the 24 values for the stainless steel layers in the 304SS-FeAl and 430SS-FeAl MIL composites are quite similar to their respective reference foils.…”