Professor Han Weizhong's team from the School of Materials Science at Xi'an Jiaotong University (XJTU) revealed, for the first time, the ultra-high intrinsic fracture toughness of titanium (Ti) by reducing oxygen impurities.

The fracture toughness of low-oxygen Ti compared with that of major metals indicates that Ti is one of the toughest metals.

Ti and its alloys, known for being lightweight, strong, and corrosion-resistant, are widely used in aerospace, marine engineering, and biomedical fields. However, despite decades of alloy design and processing improvements, the fracture toughness of Ti and its alloys has remained below 130 MPa∙m1/2, restricting its broader application.

Professor Han's team discovered that oxygen impurities in Ti are the key factor limiting its fracture toughness. Even trace amounts of oxygen can hinder Ti's deformation ability and restrict plastic deformation at the crack tip.

By reducing the oxygen content in commercially pure Ti from 0.14 percent to 0.02 percent, the research team successfully increased its fracture toughness from 117 MPa∙m1/2 to 255 MPa∙m1/2, surpassing the toughness levels of all previously reported commercially pure Ti and its alloys. Thus, low-oxygen Ti is one of the toughest metals ever recorded.

This research, titled Uncovering the Intrinsic High Fracture Toughness of Titanium via Lowered Oxygen Impurity Content, was published in the Advanced Materials. XJTU doctoral student Zou Xiaowei is the first author, with Professors Han and Ma En as corresponding authors. XJTU is the sole corresponding institution for the study.