Effect of long-term natural aging on microstructure and room temperature superplastic behavior of UFG/FG Zn-Al alloys processed by ECAP
Küçük Resim Yok
Tarih
2018
Yazarlar
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Russian Acad Sciences, Inst Metals Superplasticity Problems
Erişim Hakkı
info:eu-repo/semantics/openAccess
Özet
Two potential superplastic compositions of Zn-Al alloy systems, Zn-22Al and Zn-0.3Al alloys, were chosen and processed by equal-channel angular pressing /extrusion (ECAP /E) in order to achieve high strain rate (HSR) superplasticity at room temperature (RT). ECAP-processed samples of both alloys were then subjected to long-term natural aging up to 1100 days to evaluate the effect of long-term natural aging on their microstructures and superplastic behaviors. Before natural aging, the maximum elongations to failure at RT were 400 % for ultrafine-grained (UFG) Zn-22Al at the strain rate of 5 x 10(-2) s(-1) and 1000 % for fine-grained (FG) Zn-0.3Al at the strain rate of 1 x 10(-4) s(-1). Long-term natural aging did not cause a significant change in the elongation of UFG Zn-22Al alloy with 355 % maximum elongation. However, optimum strain rate giving the maximum elongation decreased to 3 x 10(-3) s(-1). On the other hand, Zn-0.3Al alloy lost more than half of its superplastic elongation and showed an elongation to failure of 435 % at the end of the natural aging period of 1100 days. Microstructural analyses show that grain boundary corrosion occurred in dilute Zn-0.3Al alloy during the natural aging process. Corroded grain boundaries resulted in cavity nucleation during the tensile tests and some of these cavities attained large sizes and caused premature failure.
Açıklama
Anahtar Kelimeler
room temperature superplasticity, Zn-Al alloys, natural aging, ultrafine-grained materials, ECAP
Kaynak
Letters On Materials
WoS Q Değeri
N/A
Scopus Q Değeri
Q3
Cilt
8
Sayı
4
