Study on the Stability and Phase Transition of Precipitated Phases Al₆Fe and Al₃Fe in Al-Fe Alloy

Abstract:

Based on the empirical electron theory of solids and molecules theory(EET), the valence electron structures(VESs) of the strengthening phases Al₃Fe and Al₆Fe in Al-Fe alloy are calculated, then the stability of Al₃Fe and Al₆Fe, the precipitated sequence under the non-equilibrium solidification, the phase transition during aging and the effects of alloy elements are discussed. The results show that the values of covalent electron pairs on the strongest bond n₁, the total forming bond ability F, and the number of atom state group σ_N of Al₃Fe and Al₆Fe are bigger than that of Mg₁₇Al12 and Mg₂Si, so the stability of Al₃Fe and Al₆Fe is better. The total forming bond ability of Al₆Fe is far smaller than that of Al₃Fe, so Al₆Fe generates first under the equilibrium solidification. The strongest bond of Al₆Fe is weaker than that of Al₃Fe, so Al₆Fe is easy to be broken up and form the more stable Al₃Fe finally during aging. The addition of alloy elements changes the VES of Al₆Fe and makes its values of F, σ_N and n₁ increased, the stability of Al₆Fe is strengthened too, which delays the Al₆Fe→Al₃Fe transition and improves the transition temperature.

• Periodical: Advanced Materials Research (Volumes 306-307)
• Pages: 438-442
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.306-307.438
• Online since: August 2011
• Authors: Hua Qu, Wei Dong Liu
• Keywords: Al-Fe Alloy, Phase Transition, Precipitated Phase, Stability, Valence Electron Structure

References

[1] D. Q. Tan, W. X. Li, Y. P. Tang: Materials Review Vol. 17 (2003), p.18.

[2] Y. D. Xiao, Y. A. Xie, S. R. Li: Aluminium Fabrication Vol. 17 (1994), p.24.

[3] Z. P. Zhou, J. M. Ma, R. D. Li: China Foundry Machinery and Technology Vol. 6 (2004), p.12.

[4] R. H. Yu: Chinese Science Bulletin (in Chinese), 23 (1978), p.217.

[5] R. L. Zhang: Empirical Electron Theory of Solids and Molecules (in Chinese) (Jilin Science and Technology Publishing House, Changchun 1993).

[6] M. C. Cristina, Garcia Escorial: Mater. Sci. Eng. A Vol. 134 (1991), p.1182.

[7] Z. L. Liu, Z. L. Li, W. D. Liu: Electron Structure and Properties of Interface (in Chinese) (Science Publishing House, Beijing 2002).

[8] W. D. Liu, Z. L. Liu, H. Qu: Acta Metallurgica Sinica Vol. 38 (2002) p.1037.

[9] P. J. Black: Acta Crystallo Graphica Vol. 8 (1955) p.43.