Influence of Cooling Rate and Copper Content on the Microstructure of Zn–27%Al Alloy under End-chill Casting

Document Type : Original Articles

Authors

• Rahim Arabi Jeshvaghani
• Hamid Pirnajmoddin
• Hassan Ghahvechian
• Hamid Reza Shahverdi

Tarbiat Modares University

10.22067/ma.v28i2.35765

Abstract

In this research, the effect of cooling rate and copper content on the microstructure of Zn–27%Al alloy was investigated using chilled casting in a sand mould. Microstructural examination showed that with decreasing cooling rate, dendrite arm spacing and the percentage of interdendritic phases increased. Moreover, addition of copper up to 1 wt. % did not lead to significant change in microstructure, while addition of 2, and 4 wt% copper led to the formation of -CuZn4 phase in the interdendritic regions. In addition, with decreasing cooling rate, the morphology of - precipitates varied from semi-plate-like to spherical.

Keywords

• End-Chill Casting
• ZA27 Alloy
• Microstructure
• Cooling rate

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References

1. Rosale H.J.D., Hirata V.M.L., Velazquez J.L.M., Munoz M.L.S., "Microstructure characterization of phase transformations in a Zn-22 wt% Al-2 wt% Cu alloy by XRD, SEM, TEM and FIM", Journal of Alloys and Compounds, Vol. 313, pp. 154-160, (2000).

2. Savaskan T., Aydiner A., "Effects of silicon content on the mechanical and tribological properties of monotectoid-based zinc–aluminium–silicon alloys", Wear, Vol. 257, pp. 377-388, (2004).

3. Savaskan T., Alemdag Y., "Effect of nickel additions on the mechanical and sliding wear properties of Al-40Zn-3Cu alloy", Wear, Vol. 268, pp. 565-570, (2010).

4. Savaskan T., Aydıner A., "Effects of silicon content on the mechanical and tribological properties of monotectoid-based zinc-aluminium-silicon alloys", Wear, Vol. 257, pp. 377-388, (2004).

5. Savaskan T., Turhal M.S., "Relationships between cooling rate, copper content and mechanical properties of monotectoid based Zn-Al-Cu alloys", Materials Characterization, Vol. 51, pp. 259-270, (2003).

6. Zhu Y.H., Lee W.B., "Tensile deformation and phase transformation of furnace-cooled Zn–Al based alloy", Materials Science and Engineering A, Vol. 293, pp. 95-101, (2000).

7. Mojaver R., Shahverdi H.R., "The relationship between the wear behavior and microstructure features in end-chill cast Zn-27%Al alloy", Wear, Vol. 268, pp. 605-611, (2010).

8. Turhal M.S., Savaskan T., "Relationships between secondary dendrite arm spacing and mechanical properties of Zn-40Al-Cu alloys", Journal of Materials Science and Engineering A, Vol. 38, pp. 2639-2646, (2003).

9. Givanildo A., Santos A., Garcia A., "Design of mechanical properties of a Zn27Al alloy based on microstructure dendritic array spacing", Materials and Design, Vol. 28, pp. 2425-2430, (2007).

10. Osorio W.R., Garcia A., "Modeling dendritic structure and mechanical properties of Zn-Al alloys as a function of solidification conditions", Materials Science and Engineering A, Vol. 325, pp. 103-111, (2002).

11. Osorio W.R., Garcia A., "Effect of dendritic arm spacing on mechanical properties and corrosion resistance of Al 9 Wt Pct Si and Zn 27 Wt Pct Al alloys", Metallurgical and Materials Transaction A, Vol. 37, pp. 2525-2538, (2006).

12. Gündüz M., Cadirli E., "Directional solidification of aluminum-copper alloys", Materials Science and Engineering A, Vol. 327, pp. 167-185, (2002).

13. Ares A.E., Schvezov C.E., "Influence of solidification thermal parameters on the columnar-to-equiaxed transition of Al-Zn and Zn-Al alloys", Metallurgical and Materials Transactions A, Vol. 38, pp. 1485-1499, (2007).

14. Jiefang W., Shuqing Y., Jingpei X., Zhongxia L., Jiwen L., Wenyan W., "Effect of cooling rate on the microstructure of ZA48 alloy", Journal of Wuhan University of Technology-Mater. Sci. Ed., Vol. 25, pp. 811-813, (2010).

15. Caceres C.H., Davidson C.J., Griffiths J.R., Newton C.L., "Effects of solidification rate and ageing on the microstructure and mechanical properties of AZ91 alloy", Materials Science and Engineering A, Vol. 325, pp. 344-355, (2002).

16. Flemings M.C., "Solidification processing", McGraw-Hill, USA, (1974).

17. ASM Handbook, "Alloy Phase Diagrams", Vol. 3, ASM International, USA, (1992).

18. Chen H., Xin X., Dong D.Y., Ren Y.P., Hao S.M., "Study on the stability of T' phase in the Al-Zn-Cu ternary system", Acta Metallurgica Sinica, Vol. 17, pp. 269-273, (2004).

19. Savaskan T., Hekimoglu A.P., Purcek G., "Effect of copper content on the mechanical and sliding wear properties of monotectoid-based zinc-aluminium-copper alloys", Tribology International, Vol. 37, pp. 45-50, (2004).