牛焱
,
吴维
中国腐蚀与防护学报
研究了含Ｎｂ１５和３０ｗｔ％的Ｃｏ－Ｎｂ二元合金在ｌａｔｉｎ纯氧中６００～８００℃的氧化特性。它们的氧化动力学近似地遵循抛物线规律，而其瞬时氧化速率常数随时间而减低、且以６００℃氧化者尤甚。两合金的氧化速率均高于纯Ｃｏ，但其速率增量颇低。在所有的实验条件下，两合金都发生了外氧化与内氧化，外氧化膜的外侧为连续的纯氧化钴带，其下为两个二元Ｃｏ－Ｎｂ氧化物（ＣＯＮｂ２Ｏ６和ＣＯ４Ｎｂ２Ｏ９）与基金属氧化物的混合。内氧化带为氧化钴、氧化铌（Ｎｂ２Ｏ５或／和ＮｂＯ２）的混合，而在该带的最外侧还有源于富Ｎｂ合金相的二元氧化物。在合金－氧化膜界面处都没有观察到贫铌带。从合金的和所生成氧化膜的显微组织特征，尤其是从铌在钴中溶解度低的角度，对合金的氧化行为进行了讨论。
关键词:
Ｃｏ－Ｎｂ合金
,
High temperature
,
Oxidation
Dawu Xiao Yinglei Li Shisheng Hu Lingcang Cai
材料科学技术（英）
High temperature mechanical behaviors of zirconium at high strain rate of 103 s-1 were studied by split Hopkinson pressure bar (SHPB). The influences of strain rate and temperature on the micro-structural evolution, as well as the occurrence of shear localization and subsequent fracture, were also investigated. It's found that the compressive stress-strain response depends sensitively on the applied strain rate and test temperature. Micro-structural observations revealed that the density of the twinning grains reduced as the temperature increased, and increased in response to increasing strain rate. Optical observation of the fracture surfaces showed evidence of adiabatic shear localization along the fracture planes prior to crack formation. Finally, a special form of the Zerilli-Armstrong model was used to describe the mechanical response of zirconium.
关键词:
Zirconium
,
高温
,
应变率
,
绝热剪切带
