中國(guó)有色金屬學(xué)報(bào)(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 23 No. 10 October 2013 |
（1. School of Materials Science and Engineering, Beihang University, Beijing 100191, China;
2. Department of Military Logistics, Military Transportation University, Tianjin 300161, China）
Abstract:Nb-16Si-24Ti-10Cr-2Al-2Hf alloy was directionally solidified with withdrawal rates of 1.2, 6, 18, 36 and 50 mm/min and then heat treated at 1400, 1450 and 1500 °C with withdrawal rate of 50 mm/min for 10 h. The effects of withdrawal rate and heat treatment temperature on the microstructure were studied. The microstructure of directionally solidified alloy was composed of the primary Nb5Si3, Nbss/Nb5Si3 eutectic cells and Cr2Nb, which distribute paralleled to the growth direction. The microstructure becomes more refined with the increasing withdrawal rate, accompany with the evolution of eutectic cells morphology. After heat treatment, Nbss phase connects and forms a continuous matrix, and the Cr2Nb phase becomes smaller and distributes more dispersedly. After heat treatment at 1450 °C for 10 h, the alloy achieves balance between the optimization of microstructure and alleviation of solute segregation.
Key words: Nb-Si alloy; directional solidification; eutectic; withdrawal rate; microstructure; heat treatment
