Theoretical study of structural and thermal
properties of Fe
2(Zr, Nb) Laves alloys
L.Rabahi1, A. Kellou2, D. Bradai1
1 Faculté de physique, Laboratoire physique des matériaux, Université des sciences et de la technologie Houari Boumediene USTHB B.P.32, El Alia, 16111, Bab Ezzouar, Alger, ALGERIA
rabahil@yahoo.fr
2 Faculté de physique, Laboratoire physique théorique, Université des sciences et de la technologie Houari Boumediene USTHB B.P.32, El Alia, 16111, Bab Ezzouar, Alger, ALGERIA
Introduction:
Alloys based on the Fe-Al phases matrix represent a promising class of intermetallics with great potential for substituting stainless steels for applications at elevated temperatures. This is due to their high strength, excellent resistance against corrosion, low cost of the constituents and a lower density compared to that of many other iron-based materials. The principal shortcoming is their pronounced brittleness at ambient temperature which has been tried to be overcome by micro and macro alloying. Among the elemental addition are Zr and Nb that form intermetallics compounds named Laves phases.
The aim of this is to use ab initio calculations (with the (PP) Pseudopotential method) to give new insights on structural and thermal properties of binary and ternary C15-Laves Fe2(Zr,Nb) alloys. The temperature effects have been obtained using the quasi-harmonic Debye model exploiting the total energy calculations of the PP method.
0 200 400 600 800 1000
10,3 10,4 10,5 10,6 10,7 10,8
Cell Parameter (Bohr)
T em pera ture (K) Fe2Zr
Fe2N b Fe16 N b2 Zr6 Fe4ZrN b
The main results show that:
1) The structural properties obey to the Vegard’s law, meaning that Fe2(Zr, Nb) are quite ordered alloys independent of the Zr/Nb ratio.
2) The use of the quasi-harmonic Debye model was successfully applied to determine the thermal properties of the Fe2(Zr, Nb) alloys in the 0-1000 K temperature range. The effect of temperature on bulk modulii and volume expansions is important in Fe2Nb while lesser in Fe2Zr.
References:
A. Kellou, T. Grosdidier, C. Coddet, H. Aourag, (2005). acta materialia, Volume 53, Issue 5
F. Moret, R. Baccino, P. Martel, L. Guetaz, (1996), Journal de physique IV, Vol6,.
J. Adamiec, M. Kalka, (2006), Journal of Achievements in Materials and Manufacturing Engineering, Volume 18, Issue1-2.
L.Rabahi, Mémoire de Magister, (2010), USTHB Alger, M.A.Blanco et al(2004), Computer Physics
Communications I58.
M. Martinez Celis, Thèse de Doctorat, (2007), Institut National Polytechnique de Toulouse,
. Compund
Cell parameter a0 (Bohr)
Bulk Modulus B (GPa)
Fe2Zr 13.347 139.5
Fe2(Zr0.75Nb0.25) 13.252 143.2
Fe2(Zr0.5Nb0.5) 13.152 152.3
Fe2(Zr0.25Nb0.75) 13.046 160.2
Fe2Nb 12.940 166.1
