Microstructural Evolution and Mechanical Behaviors of an Nb-16Si-22Ti-2Al-2Hf Alloy with 2 and 17 at. pct Cr Additions at Room and/or High Temperatures
Microstructural Evolution and Mechanical Behaviors of an Nb-16Si-22Ti-2Al-2Hf Alloy with 2 and 17 at. pct Cr Additions at Room and/or High Temperatures
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DOI：
10.1007/s11661-014-2423-x
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发表时间：
2014-07
期刊：
影响因子：
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通讯作者：
C. Yang;L. Jia;Chungen Zhou;Hu Zhang;J. Sha
中科院分区：
文献类型：
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作者：
C. Yang;L. Jia;Chungen Zhou;Hu Zhang;J. Sha
用X射线衍射仪、扫描电子显微镜和透射电子显微镜研究了Nb-16Si-22Ti-2Al-2Hf-(2，17)Cr合金(以下简称2Cr合金和17Cr合金)的显微组织和取向关系。比较了两种合金在室温和高温下的力学性能。2Cr合金由NbSS和(α+β)-Nb5Si3相组成，17Cr合金由具有C15结构的NbSS、(α+β)-Nb5Si3和Laves Cr2Nb相组成。β-Nb5Si3和Laves Cr2Nb相相对于NbSS相表现出不同的OR。发现Laves Cr2Nb相对室温断裂韧性和1523~1623℃(1250~1350℃)的抗压强度有负作用。当名义铬含量从2%增加到17%时，1623℃(1350℃)下的断裂韧性和压缩屈服强度分别从14.4降至10.3 Mpa/1/2和从300降至85 Mpa。最后，研究和讨论了这些典型的NbSS/Nb5Si3和NbSS/Nb5Si3/Cr2Nb显微组织在室温和高温下的弯曲和压缩条件下的断裂模式。
X-ray diffraction analysis, scanning electron microscopy, and transmission electron microscopy were used to investigate the microstructures and orientation relationships (ORs) of Nb-16Si-22Ti-2Al-2Hf-(2,17)Cr alloys (hereafter referred to as 2Cr and 17Cr alloys, respectively). The mechanical properties of the two alloys at room and/or high temperatures were compared. The 2Cr alloy comprised NbSSand (α + β)-Nb5Si3phases, while the 17Cr alloy consisted of NbSS, (α + β)-Nb5Si3and Laves Cr2Nb phases with a C15 structure. The β-Nb5Si3and Laves Cr2Nb phases exhibited variable ORs with respect to the NbSSphase. The Laves Cr2Nb phase was found to play a negative role on the fracture toughness at room temperature and on the compressive strength at temperatures from 1523 K to 1623 K (1250 °C to 1350 °C). The fracture toughness and the compressive yield strength at 1623 K (1350 °C) both decreased from 14.4 to 10.3 MPa m1/2and from 300 to 85 MPa, respectively, when the nominal Cr content increased from 2 to 17 at. pct. Finally, the fracture modes of these typical NbSS/Nb5Si3and NbSS/Nb5Si3/Cr2Nb microstructures under bending and compression conditions at room and high temperatures were investigated and discussed.