摘要
用电磁冷坩埚定向凝固制备了Nb-24Ti-12Si-4Cr-4Al-2Hf(at%)合金。X射线衍射分析(XRD)表明初始生长区和稳态生长区内的物相均为Nbss,β-Nb5Si3和γ-Nb5Si3。通过透射电镜明场像(BFI)和选区电子衍射斑点分析(SADP)确定呈六边形小平面相的硅化物是γ-Nb5Si3,条状或片状形态的硅化物是β-Nb5Si3。扫描电子显微镜照片(BEI)表明:初始生长区和稳态生长区内的组织均由初生的Nbss和Nbss/Nb5Si3共晶组成,其中共晶分为Nbss/β-Nb5Si3和Nbss/γ-Nb5Si3;初始生长区的横截面组织存在2种形态的胞状共晶;稳态生长区的横截面组织存在3种形态的胞状共晶;与初始生长区内的组织相比,稳态生长区内的组织较为细小且分布均匀;γ-Nb5Si3的生长在稳态生长区内受到抑制。
The Nb-24Ti-12Si-4Cr-4Al-2Hf（at%） alloy was prepared by electromagnetic cold crucible directional solidifcation.The XRD analysis shows that the initial growth zone（IGZ） and the steady-state growth region（SSGR） are composed of priamry Nbss,β-Nb5Si3 and γ-Nb5Si3.The BFI and SADP indicate that the hexagonal faceted silicide is γ-Nb5Si3 and the rod-like or sheet silicide is β-Nb5Si3.The BEI illustrates that both IGZ and SSGR consist of primary Nbss and Nbss＋Nb5Si3 eutectic,including Nbss＋β-Nb5Si3 and Nbss＋γ-Nb5Si3 eutectic.In terms of morphology,two types of cellular eutectic coexist in the transverse microstructure of IGZ,but three types of cellular eutectic are present in the transverse microstructure of SSGR.The microstructure in SSGR is finer and distributed more evenly compared with that in IGZ.The growth of γ-Nb5Si3 in SSGR is inhibited.
出处
《稀有金属材料与工程》
SCIE
EI
CAS
CSCD
北大核心
2014年第10期2419-2424,共6页
Rare Metal Materials and Engineering
