High Temperature Properties of Equialomic FeAl with Ternary Additions

Abstract

The aluminide intermetallic compounds are considered potential structural materials for aerospace applications. The B2 binary aluminide FeAl has a melting point in excess of 1500 K, is of simple cubic structure, exist over a wide range of composition with solubility for third elements and is potentially self-protecting in extreme environments. The B2 FeAl compound has been alloyed with 1 to 5 at % ternary additions of Si, Ti, Zr, Hf, Cr, Ni, Co, Nb, Ta, Mo, W, and Re. The alloys were prepared by blending a third elemental powder with pre-alloyed binary FeAl powder. Consolidation was by hot extrusion at 1250 K.Annealing studies on the extruded rods showed that the third element addition can be classified into three categories based upon the amount of homogenization and the extent of solid solutioning. Constant strain rate compression tests were performed to determine the flow stress as a function of temperature and composition. The mechanical strength behavior was dependent upon the third element homogenization classification.

Microstructural Changes of Al Hot-Dipped P91 Steel during High-Temperature Oxidation

“…The increment of the surface hardness of the hot-dip aluminized P91 steel improves the wear resistance and thereby the performance of structural components [13]. Figure 7b,c, it is seen that the ~35 μm-thick (α-Al2O3, Fe2O3)-mixed oxide layer either detached or adherent (spots 1-2), ~90 μm-thick AlFe3 layer (spots [3][4][5], and the ~255 μm-thick Fe(Al) coating (spots 6-18; α-Fe layer dissolved with some Al) existed on the substrate (spots [19][20][21][22]. Iron diffused outwardly to form Fe2O3 (Figure 7a), whose amount was smaller than that of α-Al2O3 (spots 1-2 in Figure 7c).…”

“…In Figure 5e, the major alloying element, Cr, diffused up to the surface to dissolve in the α-Al 2 O 3 layer. The second major alloying element, Mo, was denuded at the upper part of the coating owing to its small solubility in AlFe [20]. The third major alloying element, Mn, was present in the whole coating.…”

Concepts derived from phase diagram studies for the strengthening of Fe–Al-based alloys

“…The two ternary compounds, which are in equilibrium with the Fe-Al phases, are either a Laves phase (l, with l 0 denoting the cubic C15 structure and l 1 denoting the hexagonal C14 structure) or the tetragonal ThMn 12 -type phase (Fe,Al) 12 Zr (t 1 ). a single element to Fe-Al-based alloys is known to the present author, though some individual data do exist [50,61].…”

Mechanical properties and oxidation behaviour of two-phase iron aluminium alloys with Zr(Fe,Al)2 Laves phase or Zr(Fe,Al)12 τ1 phase

“…In addition, a beneficial effect on the ductility and fatigue crack growth resistance was found in the same investigation for additions of 0.1 and 0.5at.% Zr, but both properties deteriorated again in an alloy with 1at.% Zr. Intermetallics 13 (2005) The mechanical behaviour of Fe-Al alloys with higher Zr contents (O1at.%) was studied by compression tests on alloys of composition Fe-39Al-5Zr, Fe-40Al-2Zr [27], and Fe-47Al-5Zr [28]. The flow stresses at about 1000 8C were found to be significantly increased compared to binary alloys.…”