Microstructural evolution during creep of 9Cr-ODS steels
Microstructural evolution during creep of 9Cr-ODS steels
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DOI：
10.1016/j.fusengdes.2005.09.045
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发表时间：
2006-02
影响因子：
1.7
通讯作者：
H. Sakasegawa;S. Ohtsuka;S. Ukai;H. Tanigawa;M. Fujiwara;H. Ogiwara;A. Kohyama
中科院分区：
文献类型：
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作者：
H. Sakasegawa;S. Ohtsuka;S. Ukai;H. Tanigawa;M. Fujiwara;H. Ogiwara;A. Kohyama
9 Cr-ODS（氧化物弥散强化）钢正被开发用于快中子增殖堆和聚变堆的结构材料。该钢的特征在于细小的Y-Ti-O复合氧化物颗粒弥散分布在基体中。因此，许多研究通过利用透射电子显微镜（TEM）观察关注氧化物颗粒和位错来研究蠕变特性，但是这样的研究仍然不足以阐明蠕变机制。在这项工作中，一个潜在的微观结构特征影响蠕变性能，事先颗粒边界（PPB）的蠕变过程中形成的空腔和对齐沿着挤压方向，进行了研究。场发射枪扫描电子显微镜（FE-SEM）观察蠕变试样表明PPB空腔增强蠕变裂纹扩展。通过固结两种不同粒度的机械合金化（MA）粉末（>90 μ m和<45μm），定量研究了PPB孔洞对蠕变性能的影响。当使用较大的MA粉末时，PPB空腔减少，并且平行于挤出方向的蠕变性能得到改善。可以得出结论，PPB是影响蠕变性能的重要微观结构特征之一，PPB空腔的减少意味着改善。
9Cr-ODS (oxide dispersion strengthened) steels are being developed for structural materials of fast breeder reactors and fusion reactors. The steels can be characterized by small Y–Ti–O complex oxide particles dispersed in the matrix. Thus, many researches have studied creep properties by focusing on oxide particles and dislocations with transmission electron microscopy (TEM) observations, but such studies are still insufficient to clarify the creep mechanism. In this work, a potential microstructural feature affecting creep properties, prior particle boundary (PPB) cavities formed during creep and aligned along the extrusion direction, was studied. Field emission gun-scanning electron microscopy (FE-SEM) observations on the crept specimens indicated PPB cavities enhanced creep crack propagation. The effect of PPB cavities on creep properties were quantitatively studied by consolidating two different sizes mechanical alloying (MA) powders (>90 and <45μm). PPB cavities decreased when using the larger MA powder and creep properties parallel to the extrusion direction were improved. It is concluded that PPB is one of the important microstructural features affecting creep properties, where a reduction in PPB cavities signifies an improvement.