Insight into point defects and impurities in titanium from first principles

Sanjeev K. Nayak, Cain J. Hung, Vinit Sharma, S. Pamir Alpay, Avinash M. Dongare, William J. Brindley, Rainer J. Hebert

Index: 10.1038/s41524-018-0068-9

Full Text: HTML

Abstract

Titanium alloys find extensive use in the aerospace and biomedical industries due to a unique combination of strength, density, and corrosion resistance. Decades of mostly experimental research has led to a large body of knowledge of the processing-microstructure-properties linkages. But much of the existing understanding of point defects that play a significant role in the mechanical properties of titanium is based on semi-empirical rules. In this work, we present the results of a detailed self-consistent first-principles study that was developed to determine formation energies of intrinsic point defects including vacancies, self-interstitials, and extrinsic point defects, such as, interstitial and substitutional impurities/dopants. We find that most elements, regardless of size, prefer substitutional positions, but highly electronegative elements, such as C, N, O, F, S, and Cl, some of which are common impurities in Ti, occupy interstitial positions.