Developing Pure Titanium with 1 GPA Tensile Strength and 24% Elongation by Interstitial Oxygen Doping

Abstract

Interstitial oxygen ([O]), sitting in the octahedral sites, could strengthen titanium (Ti) and its alloys efficiently. However, oxygen tends to segregate along matrix grain boundaries, which could cause severe embrittlement. Herein, we utilized a plenary ball milling process to gradually introduce oxygen into pure Ti, which was found to be capable of doping up to 0.63 wt.% of equivalent interstitial oxygen ([O]eq=[O]+2[N], in wt.%) into the Ti matrix homogeneously. Tensile tests revealed that the fabricated Ti-O materials possessed mechanical properties superior to those of conventional Ti materials alloyed by much more expensive elements such as V, Mo, etc. In addition, the Ti-O with 0.63 wt.% of [O]eq exhibited a high tensile strength of 1018 MPa, which corresponds to a strengthening efficiency as high as 624 MPa per wt.% of [O]eq. Meanwhile, 24.2% of elongation was maintained. A quantitative analysis on strengthening mechanism further confirmed the superior strengthening effect of interstitial oxygen via solid solution strengthening. This study may provide guidance for the development of high-performance yet cost-effective Ti materials.

Keywords: Ti-O material, Interstitial oxygen, Power metallurgy, Tensile property, Solid solution strengthening