TY - JOUR

T1 - Influence of Nb on Ti diffusion in γ-TiAl intermetallics studied by mechanical spectroscopy

AU - Ibanez-Perez, J.

AU - No, Maria L.

AU - Oehring, M.

AU - Clemens, Helmut

AU - San Juan, J.M.

N1 - Publisher Copyright: © 2021 The Author(s)

PY - 2021/6/25

Y1 - 2021/6/25

N2 - The development of intermetallic titanium aluminides has been driven by the aeronautic and aerospace industries because of the excellent mechanical properties and low density of γ-TiAl based alloys. Up to now, several generations of γ-TiAl based alloys were developed with increasing complexity of the alloy systems. Nb is one of the most important alloying elements in γ-TiAl alloys and although it is considered as a slow diffuser, its influence has not been fully quantified yet. In this work we demonstrate, through mechanical spectroscopy measurements conducted on several γ-TiAl based alloys with different Nb content, that Nb impedes the diffusion of Ti atoms in the α 2-Ti 3Al phase. Internal friction measurements show a relaxation peak P(α 2), which is associated with short distance diffusion of Ti atoms in the α 2 phase, involving stress-induced rotation of dipoles Al-V Ti-Al, whose activation energy is dependent on the Nb content. The increase of the activation energy is quantified as ΔE a(Ti)= 0.037 eV × at% Nb, being attributed to the next-neighbor interaction of Nb atoms with the local configuration of Ti-V Ti. This mechanism also produces a further broadening of the relaxation peak, which is attributed to the near-next-neighbor interactions for high Nb contents. Finally, an atomic model for the mechanism responsible for this relaxation is proposed allowing to explain the observed experimental behavior.

AB - The development of intermetallic titanium aluminides has been driven by the aeronautic and aerospace industries because of the excellent mechanical properties and low density of γ-TiAl based alloys. Up to now, several generations of γ-TiAl based alloys were developed with increasing complexity of the alloy systems. Nb is one of the most important alloying elements in γ-TiAl alloys and although it is considered as a slow diffuser, its influence has not been fully quantified yet. In this work we demonstrate, through mechanical spectroscopy measurements conducted on several γ-TiAl based alloys with different Nb content, that Nb impedes the diffusion of Ti atoms in the α 2-Ti 3Al phase. Internal friction measurements show a relaxation peak P(α 2), which is associated with short distance diffusion of Ti atoms in the α 2 phase, involving stress-induced rotation of dipoles Al-V Ti-Al, whose activation energy is dependent on the Nb content. The increase of the activation energy is quantified as ΔE a(Ti)= 0.037 eV × at% Nb, being attributed to the next-neighbor interaction of Nb atoms with the local configuration of Ti-V Ti. This mechanism also produces a further broadening of the relaxation peak, which is attributed to the near-next-neighbor interactions for high Nb contents. Finally, an atomic model for the mechanism responsible for this relaxation is proposed allowing to explain the observed experimental behavior.

UR - http://www.scopus.com/inward/record.url?scp=85100615384&partnerID=8YFLogxK

U2 - 10.1016/j.jallcom.2021.158880

DO - 10.1016/j.jallcom.2021.158880

M3 - Article

VL - 867.2021

JO - Journal of alloys and compounds

JF - Journal of alloys and compounds

SN - 0925-8388

IS - June

M1 - 158880

ER -