Structural Stability of the High-Aluminium Zinc Alloys Modified with Ti Addition
The subject of the paper is structural stability of the Zn-26 wt.% Al binary alloys doped with 2.2 wt.% Cu or 1.6 wt.% Ti addition. The structural stability of Zn-Al alloys with increased Al content is connected with stability of solid solution of zinc in aluminium α', which is the main component of these alloys microstructure. Such a solution undergoes phase transformations which are accompanied, among others, by changes in dimensions and strength properties.
The structural stability of the ZnAL26Cu2.2 and ZnAl26Ti1.6 alloys was investigated using XRD examinations during long term natural ageing after casting, as well as during long term natural ageing after super-saturation and quenching. On the basis of the performed examinations it was stated that small Ti addition to the binary ZnAl25 alloy, apart from structure refinement, accelerates decomposition of the primary α' phase giving stable structure in a shorter period of time in comparison with the alloy without Ti addition. Addition of Ti in amount of 1.6 wt.%, totally replacing Cu, allows obtaining stable structure and dimensions and allows avoiding structural instability caused by the metastable e-CuZn4 phase present in the ZnAl26Cu2.2 alloy.
Kubel, E. J. (1987). Expanding Horizonts for ZA Alloys. Metal Progress. 7, 51.
Barnhurst, R. J. (1991). A practical Approach to ZA Alloys. Foundry Trade Journal. 165, 962.
Ayiuk, O., Ghoreshy, M., Sahoo, M. & Smith, R. W. (1998). Solidification and Foundry Studies of Zn-Al Alloys for Use in Cast-to-Shape Applications. Journal of the Institute of Metals, 116, 315.
Ciach, R., Krol, J., & Wegrzyn-Tasior, K. (1969). Studies on Four Phases Transformation in AlZn78 Alloy Containing 1-3 per cent of Copper. Bull. Acad. Pol. Sci. - Ser. Techn. 17 (4), 13.
Wang, H., Luo, M., Chen, Y. & Wu, Y. (1996). The Time-Temperature-Transition (TTT) of ZA27 Alloy. Journal of Materials Science Letters. 15, 1006-1008.
Zhu, Y. H. & Goodwin, F. E. (1993). Influence of Rare Earth Element on Phase Transformation in the Zn-27%Al Based Alloy. Journal of Materials Research. 8, 3043.
Zhu, Y. H., Yan, B. & Villasenor Torres, G. (1994). Phase Transformations of a Zn-Al Based Alloy Containing a Small Amount of Rare Earth Element. Journal of Materials Processing Technology. 47, 73.
Zhu, Y. H. & Murphy, S. (1986). A General Rule of Decomposition Reaction in Supersaturated Zn-Al Based Alloys. Chin. Journal of Materials Science and Technology. 2, 105.
Krajewski, W. (1997). X-ray Investigation of the ZnAl25Ti Alloy Structure Stability. Metallurgy and Foundry Engineering. 23, 77.
Krajewski, W. (1995). The Effect of Ti Addition on Properties of Selected Zn-Al Alloys. Physica Status Solidi (A). 147, 389.
Krajewski, W. (1994). The Effect of Ti Addition on the Kinetics and Enthalpy of the Supersaturated ZnAl Alloy Phase Transformation. Physica Status Solidi (A). 142, 75.
Krajewski, W. (1996). Research of Heterogeneous Nucleation Mechanism in High-Aluminium Zinc Alloys Modified by Ti Addition. Monograph No.52. Krakow: AGH University of Science and Technology. (in Polish).
Krajewski, W. (1996). Phases of Heterogeneous Nucleation in the ZnAl25 Alloy Modified by Zn-Ti and Al-Ti Master Alloys. Zeitschrift für Metallkunde. 87, 645.
Krajewski, W. (1999). Investigation of the High-Aluminium Zinc Alloys Grain Refinement Process due to Ti Addition. Archives of Metallurgy. 44, 51-64.
Krajewski, W. K. & Greer, A. L. (2006). EBSD Study of ZnAl25 Alloy Inoculated with ZnTi4 Master Alloy. Materials Science Forum. 508, 281-286.
Krajewski, W. K. (2005). Structure and Properties of High-Aluminium Zinc Alloys Inoculated with Ti Addition (retrospective coverage). Archives of Foundry. 5 (15), 231-240.
Zak, P. (2010). SEM and XRD Examination of Al-Zn Alloys Inoculated with Various Grain Refiners. Marie Curie Host Fellowship report, University of Cambridge, Department of Materials Science and Metallurgy, Cambridge UK, September (in Polish, unpublished).
Krajewski, W. K. et. al. (2012). Dimensional Stability of the High-aluminium Zinc Alloys Modified with Ti Addition. Ljevarstvo. to be published.