Elimination of oxygen sensitivity in α-titanium by substitutional alloying with Al

Yan Chong; Ruopeng Zhang; Mohammad S Hooshmand; Shiteng Zhao; Daryl C Chrzan; Mark Asta; J W Morris Jr; Andrew M Minor

doi:10.1038/s41467-021-26374-w

Elimination of oxygen sensitivity in α-titanium by substitutional alloying with Al

Nat Commun. 2021 Oct 25;12(1):6158. doi: 10.1038/s41467-021-26374-w.

Authors

Yan Chong^#^{1

2}, Ruopeng Zhang^#^{1

2}, Mohammad S Hooshmand¹, Shiteng Zhao^{1

2

3}, Daryl C Chrzan^{1

4}, Mark Asta^{1

4}, J W Morris Jr¹, Andrew M Minor^{5

6

7}

Affiliations

¹ Department of Materials Science and Engineering, University of California, Berkeley, CA, USA.
² National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
³ School of Materials Science and Engineering, Beihang University, Beijing, 100191, China.
⁴ Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
⁵ Department of Materials Science and Engineering, University of California, Berkeley, CA, USA. aminor@berkeley.edu.
⁶ National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, USA. aminor@berkeley.edu.
⁷ Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA. aminor@berkeley.edu.

^# Contributed equally.

Abstract

Individually, increasing the concentration of either oxygen or aluminum has a deleterious effect on the ductility of titanium alloys. For example, extremely small amounts of interstitial oxygen can severely deteriorate the tensile ductility of titanium, particularly at cryogenic temperatures. Likewise, substitutional aluminum will decrease the ductility of titanium at low-oxygen concentrations. Here, we demonstrate that, counter-intuitively, significant additions of both Al and O substantially improves both strength and ductility, with a 6-fold increase in ductility for a Ti-6Al-0.3 O alloy as compared to a Ti-0.3 O alloy. The Al and O solutes act together to increase and sustain a high strain-hardening rate by modifying the planar slip that predominates into a delocalized, three-dimensional dislocation pattern. The mechanism can be attributed to decreasing stacking fault energy by Al, modification of the "shuffle" mechanism of oxygen-dislocation interaction by the repulsive Al-O interaction in Ti, and micro-segregation of Al and O by the same cause.

Grants and funding

N00014-19-1-2376/United States Department of Defense | United States Navy | ONR | Office of Naval Research Global (ONR Global)