Effect of Si content on mechanical properties of Nb-Si based alloys with NbSS/ Nb5Si3 structure
(1.School of Materials Science and Engineering, Beijing University of Aeronautics and Astronautics,Beijing 100083, China
2.北京市北京航空航天大学材料科学与工程学院)
2.北京市北京航空航天大学材料科学与工程学院)
Abstract: In Nb-Si based alloys with a two-phase NbSS/ intermetallic Nb5Si3 structure, the Nb5Si3 provides high-temperature strength, while the Nb solid-solution phase, NbSS, contributes to room-temperature ductility and toughness. The results show that in Nb-15W-10Hf-xSi alloys (x = 0.5, 5 and 18, mole fraction, %), the volume fraction of the Nb5Si3 is 0 for the 0.5% Si sample, 15% for the 5% Si sample and the 50% for 18% Si sample. With increasing Si content, i.e., the Nb5Si3 fraction, the high-temperature strength is improved considerably, but room-temperature ductility and toughness are degraded. For the sample Nb-15W-10Hf-18Si with 50% Nb5Si3, the compressive strength at 1 500 ℃ and the room-temperature fracture toughness are 500 MPa and 6.8 MPa？m1/2, respectively, those for the Nb5Si3 free sample, Nb-15W-10Hf-0.5Si, are 190 MPa and 13.6 MPa？m1/2.
Key words: Nb-Si based alloys; Nb-15W-10Hf-0.5Si alloy; Nb-15W-10Hf-18Si; Nb5Si3; mechanical properties