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.
Highlights
Transition metal (TM)—aluminide intermetallics including TiAl, NiAl, FeAl and Fe3 Al have unique properties, e.g., high melting points, enhanced oxidation resistance, relatively low density, and can be used as soft magnetic materials [1,2,3,4,5,6,7]
Six-jump model lets diffusion occursites. Exclusively by both high migration enthalpy and low formation energy of vacancies dictate the existence of large nearest neighbor vacancy jumps, though diffusion occurs mostly via nearest neighbor jumps into concentrations of thermal vacancies at high temperatures and theformation quenchingenergy of these vacancies vacant sites
In Fe3 Al with D03 structure, a super lattice dislocation with a burgers vector of x111y is known to be dissociated into four super-partial dislocations with b “ a{4 x111y, bound by two types of anti-phase boundaries (APBs): the nearest-neighbor anti-phase boundary (APB) (NNAPB) and the next-nearest neighbor APB (NNNAPB) [68]
Summary
Transition metal (TM)—aluminide intermetallics including TiAl, NiAl, FeAl and Fe3 Al have unique properties, e.g., high melting points, enhanced oxidation resistance, relatively low density, and can be used as soft magnetic materials [1,2,3,4,5,6,7]. The reasons for the increased ductility after Cr addition strength, and/or the effectcross-slipping, of Cr on the surface properties through theancontribution of cleavage chromium facilitating the(ii) dislocation solid solution softening and increment in are thought to be caused by: (i) the influence of Cr on the bulk properties of binary alloys, such oxide into the passive layers and theon decrement the kinetics of water reduction reactions, which strength, and/or (ii) the effect of Cr the surfaceofproperties through the contribution of chromium as facilitating dislocation cross-slipping, solidof solution softening and anreactions, increment in cleavage oxide the passive layers andformation/adsorption the decrement the kinetics ofHowever, water reduction which leads to the ainto reduction of hydrogen [26,27,28]. We hope that each section contains enough information for the average reader to understand what has been achieved in that field, as well as satisfactory references to provide further reading if necessary
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