No abstract

No abstract

No abstract

Oxygen solute strengthening is an effective strategy to harden alloys, yet, it often deteriorates the ductility. Ordered oxygen complexes (OOCs), a state between random interstitials and oxides, can simultaneously enhance strength and ductility in high-entropy alloys. However, whether this particular strengthening mechanism holds in other alloys and how these OOCs are tailored remain unclear. Herein, we demonstrate that OOCs can be obtained in bcc (body-centered-cubic) Ti-Zr-Nb medium-entropy alloys via adjusting the content of Nb and oxygen. Decreasing the phase stability enhances the degree of (Ti, Zr)-rich chemical short-range orderings, and then favors formation of OOCs after doping oxygen. Moreover, the number density of OOCs increases with oxygen contents in a given alloy, but adding excessive oxygen (>3.0 at.%) causes grain boundary segregation. Consequently, the tensile yield strength is enhanced by ~75% and ductility is substantially improved by ~164% with addition of 3.0 at.% O in the Ti-30Zr-14Nb MEA.

With the rapid development of world's technological level and the urgent demand of national economic construction for high-performance alloy materials, traditional single-component alloys gradually fail to satisfy the increasing service requirements. Owing to their unique physical, chemical, and mechanical properties, high-entropy alloys are expected to play an important role in major engineering fields such as national defense, aviation, aerospace, marine, nuclear energy, medical care, and new energy, greatly expanding the design range of metal material compositions. In this paper, based on the specific demands of advanced high-entropy alloy materials in various fields, the characteristics and connotations of high-entropy alloy materials are summarized, and the overall situation and prospects of high-entropy alloy material development are analyzed, as well as the current status of high-entropy alloy development in China and abroad. On this basis, the gaps and deficiencies in the field of high-entropy alloys in China are pointed out. First, some basic raw materials of the high-entropy alloys still rely on imports, which severely threatens the security of the industrial