TY - JOUR
T1 - Microstructure and room-temperature fracture toughness of directionally solidified Nb-Si-Ti-Cr-Al-Hf alloy
AU - Su, Linfen
AU - Jia, Lina
AU - Feng, Yubei
AU - Zhang, Huarui
AU - Yuan, Sainan
AU - Zhang, Hu
PY - 2013/1/10
Y1 - 2013/1/10
N2 - The Nb-12Si-22Ti-14Cr-2Al-2Hf alloy (at%) was directionally solidified at 1750°C with withdrawal rates of 0.24mm/min, 1.2mm/min, 6mm/min, 18mm/min, 30mm/min, 50mm/min, 70mm/min and 100mm/min, and subsequent heat treatment was carried out at 1375°C for 10h. The microstructures and room-temperature fracture toughness of the directionally solidified and heat treated samples were investigated. The results showed that instead of the microstructure consisting of NbSS dendrites, NbSS+Nb5Si3 eutectics and Cr2Nb+Ti-rich NbSS eutectics, the microstructure composed of NbSS dendrites, Nb3Si laths and Cr2Nb+Ti-rich NbSS eutectics was observed when the withdrawal rate was higher than 30mm/min. After the heat treatment, the Nb3Si transformed into extremely fine NbSS and Nb5Si3, and the NbSS dendrites changed to be remarkably continuous. The room-temperature fracture toughness could reach a maximum of 15.7MPa ·m1/2 for the alloy withdrawn at 50mm/min plus heat treatment. It is suggested that the microstructure with fine intermetallic phases (Nb5Si3 and Cr2Nb) and continuous NbSS would be of great benefit to the room-temperature fracture toughness.
AB - The Nb-12Si-22Ti-14Cr-2Al-2Hf alloy (at%) was directionally solidified at 1750°C with withdrawal rates of 0.24mm/min, 1.2mm/min, 6mm/min, 18mm/min, 30mm/min, 50mm/min, 70mm/min and 100mm/min, and subsequent heat treatment was carried out at 1375°C for 10h. The microstructures and room-temperature fracture toughness of the directionally solidified and heat treated samples were investigated. The results showed that instead of the microstructure consisting of NbSS dendrites, NbSS+Nb5Si3 eutectics and Cr2Nb+Ti-rich NbSS eutectics, the microstructure composed of NbSS dendrites, Nb3Si laths and Cr2Nb+Ti-rich NbSS eutectics was observed when the withdrawal rate was higher than 30mm/min. After the heat treatment, the Nb3Si transformed into extremely fine NbSS and Nb5Si3, and the NbSS dendrites changed to be remarkably continuous. The room-temperature fracture toughness could reach a maximum of 15.7MPa ·m1/2 for the alloy withdrawn at 50mm/min plus heat treatment. It is suggested that the microstructure with fine intermetallic phases (Nb5Si3 and Cr2Nb) and continuous NbSS would be of great benefit to the room-temperature fracture toughness.
KW - Fracture
KW - Intermetallics
KW - Mechanical characterization
KW - Microanalysis
KW - Phase transformation
UR - https://www.scopus.com/pages/publications/84869092822
U2 - 10.1016/j.msea.2012.10.011
DO - 10.1016/j.msea.2012.10.011
M3 - 文章
AN - SCOPUS:84869092822
SN - 0921-5093
VL - 560
SP - 672
EP - 677
JO - Materials Science and Engineering: A
JF - Materials Science and Engineering: A
ER -