Effect of different processes on lamellar-free ultrafine grain formation, room temperature superplasticity and fracture mode of Zn-22Al alloy


Demirtas M. , PÜRÇEK G., YANAR H., Zhang Z. J. , Zhang Z. F.

JOURNAL OF ALLOYS AND COMPOUNDS, cilt.663, ss.775-783, 2016 (SCI İndekslerine Giren Dergi) identifier identifier

  • Cilt numarası: 663
  • Basım Tarihi: 2016
  • Doi Numarası: 10.1016/j.jallcom.2015.12.142
  • Dergi Adı: JOURNAL OF ALLOYS AND COMPOUNDS
  • Sayfa Sayıları: ss.775-783

Özet

The Zn-22 wt.% Al was processed using five different selected routes including thermal, thermomechanical and severe plastic deformation (SPD) techniques in order to produce ultrafine grained (UFG) microstructure for achieving room temperature (RT) and high strain rate (HSR) superplasticity, and to compare the same set of the results. After all routes, the microstructural evolutions and RT uniaxial tensile tests at different strain rates ranging from 1 x 10(-3) to 1 x 10(0) s(-1) were investigated. The smallest grain size was achieved to be 300 nm after the thermo-mechanical process including conventional hot and cold rolling steps. However, the lamellar microstructure of the alloy was not completely eliminated during that process. On the other hand, equal-channel angular pressing (ECAP) as one of the SPD techniques decreased the grain size down to 400 nm with a lamellar-free microstructure. The maximum elongation value was achieved to be 330% with the sample tested at 1 x 10(-3) s(-1) after a thermomechanical process including conventional hot and cold rolling, and an aging stage between these rolling steps. It was found that lamellar-free microstructure causes higher superplastic elongation even if it has higher grain size compared to the sample having partially lamellar structure. (C) 2015 Elsevier B.V. All rights reserved.