Dynamic Electropulsing Induced Phase Transformations and Their Effects on Single Point Diamond Turning of AZ91 Alloy

Duo Zhang, S. To, Yaohua Zhu, Hao Wang, Guoyi Tang

.

DOI: 10.4236/jsemat.2012.21003                

Abstract

The effects of dynamic electropulsing on microstructure changes and phase transformations of a rolled Mg-9Al-1Zn alloy were studied by using optical microscopy, X-ray diffraction, back-scattered scanning microscopy and transmission electron microscopy techniques. The decomposition of β phase was accelerated under dynamic electropulsing, compared with the conventional thermal processes. Dynamic electropulsing was less effective in affecting the phase transformations, but more effective in reducing residual stress than the static electropulsing. Dynamic electropulsing improved machinability of single point diamond turning, the mechanism of which is discussed from the point of view of dislocation dynamics.

Keywords

Electropulsing; Phase Transformations; Dislocation; Twins; Magnesium Alloy

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	Y. H. Zhu, “General Rule of Phase Decomposition in Zn-Al Based Alloys II—On Effect of External Stress on Phase Trans-formation,” Materials Transactions, Vol. 45, No. 11, 2004, pp. 3083-3097. doi:10.2320/matertrans.45.3083
[2]	O. A. Troitskii, “Elec-tromechnical Effect in Metals,” Journal of Experimental and Theoretical Physics, Vol. 10, 1969, pp. 18-22.
[3]	H. Conrade and A. F. Sprecher, “Dislocation in Solid,” Elsevier, Amsterdam, 1989, p. 497.
[4]	H. Conrad, J. White, W. D. Cao, X. P. Lu and A. F. Sprecher, “Effect of Electric Current Pulses on Fatigue Characteristics of Polycrystalline Copper,” Materials Science and Engineering: A, Vol.145, No. 1, 1991, pp. 1-12. doi:10.1016/0921-5093(91)90290-4
[5]	D. Yang and H. Conrade, “Exploratory Study into the Effects of an Electric Field and High Current Density Electropulsing on the Plastic Deformation of TiAl,” Intermetallics, Vol. 9, 2001, pp. 943-947.
[6]	J. R. Lloyd, “Electromigration in Integrated Circuit Conductors,” Journal of Physics D: Applied Physics, Vol. 32, No. 17, 1999, pp. R109-R118. doi:10.1088/0022-3727/32/17/201
[7]	S. H. Xiao, J. D. Guo and S. X. Li, “The Effect of Electropulsing on Dislocation Structures in [223] Coplanar Double-Slip-Oriented Fatigued Copper Single Crystals,” Philisophycal Magazine Letters, Vol. 82, No. 11, 2002, pp. 617-622. doi:10.1080/0950083021000030397
[8]	Y. Z. Zhou, W. Zhang, J. D. Guo and G. H. He, “Diffusive Phase Transforma-tion in a Cu-Zn Alloy under Rapid Heating by Electropulsing,” Philosophycal Magazine Letters, Vol. 84, No. 5, 2004, pp. 341-348. doi:10.1081/09500830410001664535
[9]	V. V. Stolyarov, “Deformability and Nanostructuring of TiNi Shape-Memory Alloys during Electroplastic Rolling,” Materials Science and Engineering: A, Vol. 503, No. 1-2, 2009, pp. 18-20. doi:10.1016/j.msea.2008.01.094
[10]	Y. H. Zhu, S. To, W. B. Lee, X. M. Liu, Y. B. Jiang and G. Y. Tang, “Effect of Dynamic Electropulsing on Microstructure and Elongation of a Zn-Al Based Alloy,” Materials Science and Engineering: A, Vol. 501, No. 1-2, 2009, pp. 125-132. doi:10.1016/j.msea.2008.09.080
[11]	Y. B. Jiang, G. Y. Tang, C. H. Shek and Y. H. Zhu, “On the Thermodynamics and Ki-netics of Electropulsing Induced Dissolution of ?-Mg17Al12 Phase in an Aged Mg- 9Al-1Zn Alloy,” Acta Materialia, Vol. 57, No. 16, 2009, pp. 4797-4808.
[12]	D. Zhang, S. To, Y. H. Zhu, H. Wang and G. Y. Tang, “Static Electropulsing Induced Microstructural Changes and Their Effect on the Ultra-Precision Machining of Cold-Rolled AZ91 Alloy,” Metallurgical and Materials Transactions A, 2011, in press.