Alloying by addition of oxygen interstitials during additive manufacturing provides new routes to strengthen and toughen metals and alloys. The underlying mechanisms by which such interstitial atoms lead to enhanced properties remain, however, unclear, not least due a lack of quantitative atomic-scale models linking microstructure to properties. Here using quasi-3D imaging based on multi-slice electron ptychography, we reveal the importance of a new type of interstitial-character lattice defect, namely zero-dimensional stacking domains (ZDSDs), present in high density in AM-processed oxygen-modulated pure titanium. These ZDSDs promote slip diversity, and support intense work hardening, enabling a three-fold enhancement in both strength and ductility in Ti-0.45O compared to conventional pure Ti. The work demonstrates the potential for using interstitial solutes to enhance mechanical properties in a range of critical engineering alloys.
@article{arxiv.2510.18233,
title = {Zero-Dimensional Stacking Domains Enable Strong-Ductile Synergy in Additive Manufactured Titanium},
author = {Wenjing Zhang and Jizhe Cui and Xiaoyang Wang and Shubo Zhang and Yan Chong and Andy Godfrey and Nobuhiro Tsuji and Kai Wang and Rong Hu and Jing Xue and Junyu Chen and Gang Fang and Rong Yu and Wei Liu},
journal= {arXiv preprint arXiv:2510.18233},
year = {2025}
}