Synergetic Enhancement of Hardness and Toughness in New Superconductors Ti 2 Co and Ti 4 Co 2 O

作者：Lifen Shi, KeYuan Ma, Jingyu Hou, Ying Pan, Ningning Wang, Xiaojun Xiang, Pengtao Yang, Xiaohui Yu, Huiyang Gou, Sun Jianping, Y. Uwatoko, Fabian O. von Rohr, Xiang‐Feng Zhou, Bosen Wang, Jinguang Cheng · 发表于：Chinese Physics Letters · 年份：2025 · DOI：10.1088/0256-307x/42/6/067302 · 被引用次数：2 · 研究领域：Intermetallics and Advanced Alloy Properties、MXene and MAX Phase Materials、Advanced materials and composites

Abstract Compared to traditional superhard materials with high electron density and short, strong covalent bonds, alloy materials mainly composed of metallic bonding structures typically have great toughness and lower hardness. Breaking through the limits of alloy materials is a preface and long-term topic, which is of great significance and value for improving the comprehensive mechanical properties of alloy materials. Here, we report on the discovery of a cubic alloy semiconducting material Ti 2 Co with a large Vickers of hardness H v exp ∼ 6.7 GPa and low fracture toughness of K IC exp ∼ 1.51 MPa⋅m 1/2 . Unexpectedly, the H v exp ∼ 6.7 GPa is nearly triple of the H v cal ∼ 2.66 GPa predicted by density functional theory (DFT) calculations and the K IC exp ∼ 1.51 MPa⋅m 1/2 is about one or two orders of magnitude smaller than that of ordinary titanium alloy materials ( K IC exp ∼ 30 –120 MPa⋅m 1/2 ). These specifications place Ti 2 Co far from the phase space of the known alloy materials. Upon incorporation of oxygen into structural void positions, both values were simultaneously improved for Ti 4 Co 2 O to ∼9.7 GPa and ∼2.19 MPa⋅m 1/2 , respectively. Further DFT calculations on the electron localization function of Ti 4 Co 2 X (X = B, C, N, O) vs. the interstitial elements indicate that these simultaneous imp...