论文部分内容阅读
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.
The results show that in Nb (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 volume fraction of the Nb5Si3 is 0 for the 0.5% Si sample, 15% for the 5% Si sample and the 50% for (x = 0.5, 5 and 18, mole fraction, 18% Si sample. With increasing Si content, ie, 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 ° C and the room-temperature fracture toughness are 500 MPa and 6.8 MPa · m 1/2, respectively, those for the Nb 5 Si 3 free sample, Nb-15W-10Hf-0.5Si, are 190 MPa and 13.6 MPa · m1 / 2.