Factors influencing superplasticity in the Ti-6Al-4V alloy processed by high-pressure torsion

Authors: Shahmir, H., Naghdi, F., Pereira, P.H.R., Huang, Y. and Langdon, T.G.

Journal: Materials Science and Engineering: A

Volume: 718

Pages: 198-206

ISSN: 0921-5093

DOI: 10.1016/j.msea.2018.01.091

Abstract:

Two different initial microstructures, martensitic and lamellar, were developed in a Ti-6Al-4V alloy to examine their effect on the high temperature mechanical properties and superplasticity after high-pressure torsion (HPT). Significant grain refinement was achieved in both conditions with grain sizes after HPT processing of ~30 and ~40 nm, respectively. The nanocrystalline alloy in both conditions was subjected to mechanical testing at 923–1073 K using strain rates in the range from 10−3 to 10−1 s−1. The martensitic and lamellar alloys exhibited excellent ductility at these high temperatures including superplastic elongations at 973 K with maximum elongations of 815% and 690%, respectively. The fcc phase was stable at elevated temperatures in the martensitic alloy and the results suggests the fcc phase may contribute to the superior superplastic properties of the martensitic alloy.

Source: Scopus