A series of oxygen-enhanced Zr-Hf-Ti-Nb MPEAs with high strength and outstanding damping capacity are developed through tailoring the BCC structural stability by an elaborate composition regulation. Strengthening mechanism for high strength and damping mechanism related to various Snoek-type relaxations reveals that the existence of multiple separate O-rich clusters is crucial for the improvement of properties.
Abstract
Multi-principal-element alloys (MPEAs) have gained widespread popularity due to the efficient synergetic regulation of mechanical and functional properties in a huge compositional space. Here, novel O-enhanced BCC Zr-Hf-Ti-Nb MPEAs with prominent mechanical and damping properties are developed by the composition formula of (Zr,Hf,Ti)15Nb3. The Zr14TiNb3 and Zr8Hf6TiNb3 alloys possess low BCC-β structural stability. While the Zr8Hf4Ti3Nb3 alloy has a much higher BCC-β stability, as evidenced by the fact that only few α” and ω precipitates appear in 1.8 at% oxygen-added alloy. This alloy exhibits an optimal mechanical property with a higher yield strength (σ
YS = 1000 MPa) and larger ductility (ε = 15.1%), which is ascribed to the formation of O-rich clusters in BCC matrix. Moreover, these oxygen-free and -added alloys exhibit an excellent damping capacity due to their low Young’s modulus (E < 70 GPa), as exemplified with a peak value of (tanδ)max = 0.02 for 1.8 at% oxygen-added alloy. Notably, the damping characteristics are prominent over a wide temperature range (550–800 K), which derives from the occurrence of multiple separated oxygen-rich clusters. The present findings provide an avenue to enhance mechanical and functional performances of high-temperature damping alloys.
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