Enhanced atomic diffusion of Fe–Al diffusion couple during spark plasma sintering

doi:10.1016/j.scriptamat.2015.08.012

Scripta Materialia

Volume 110, 1 January 2016, Pages 105-108

https://doi.org/10.1016/j.scriptamat.2015.08.012 Get rights and content

Abstract

The atomic diffusion of a Fe–Al system under spark plasma sintering was investigated at temperatures ranging from 773 to 873 K. A significant increase in the growth rate constant of Al₁₃Fe₄ and Al₅Fe₂ under the pulse current of spark plasma sintering was observed compared with the absence of current. The interdiffusion coefficient under pulse current was about 46 times higher than that without current at 873 K. The activation energy for the interdiffusion was 332 kJ/mol, which is higher than that without current of 155–190 kJ/mol. Although the diffusion kinetics were enhanced, the thermodynamics state is not altered.

Graphical abstract

References (29)

R. Orru et al.
Mater. Sci. Eng., R
(2009)
G. Bernard-Granger et al.
Acta Mater.
(2010)
P. Hendrickx et al.
Scripta Mater.
(2015)
W. Liu et al.
Mater. Sci. Eng., A
(2009)
Z. Zhang et al.
Scripta Mater.
(2014)
S.H. Risbud et al.
Scripta Mater.
(2013)
T.B. Holland et al.
Scripta Mater.
(2013)
N. Chawake et al.
Scripta Mater.
(2014)
J.E. Garay et al.
Acta Mater.
(2003)
J.F. Zhao et al.
Acta Mater.
(2007)

N. Bertolino et al.

Scripta Mater.

(2001)

S. Rudinsky et al.

Scripta Mater.

(2015)

W. Chen et al.

Mater. Sci. Eng., A

(2005)

H. Springer et al.

Acta Mater.

(2011)

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Enhanced atomic diffusion of Fe–Al diffusion couple during spark plasma sintering

Abstract

Graphical abstract

Mater. Sci. Eng., R

Acta Mater.

Scripta Mater.

Mater. Sci. Eng., A

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Scripta Mater.

Scripta Mater.

Scripta Mater.

Acta Mater.

Acta Mater.

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Scripta Mater.

Mater. Sci. Eng., A

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