By using high temperature optical microscopy,oxidation behaviors of poly-and single crystalline NbSi_(2) were observed in-situ at 1023 K.The effects of micro-cracks,porosity and grain boundary on the oxidation behavio...By using high temperature optical microscopy,oxidation behaviors of poly-and single crystalline NbSi_(2) were observed in-situ at 1023 K.The effects of micro-cracks,porosity and grain boundary on the oxidation behavior of NbSi_(2) have been studied.The results indicate that new cracks initiate and extend from the pre-existing cracking areas in the arc-melted poly-crystalline specimen,leading to fragmentation after 220 min at 1023 K.However,although pores and grain boundary are the preferential oxidation site,they do not directly lead to fragmentation during oxidation,indicating that the pre-existing cracks in specimen are the key reason to pesting.The oxidation kinetics of the studied NbSi_(2) specimens corresponds well with the in-situ observation.展开更多
基金This work was supported by the National Natural Science Foundation of China(Grant No.50131030).
文摘By using high temperature optical microscopy,oxidation behaviors of poly-and single crystalline NbSi_(2) were observed in-situ at 1023 K.The effects of micro-cracks,porosity and grain boundary on the oxidation behavior of NbSi_(2) have been studied.The results indicate that new cracks initiate and extend from the pre-existing cracking areas in the arc-melted poly-crystalline specimen,leading to fragmentation after 220 min at 1023 K.However,although pores and grain boundary are the preferential oxidation site,they do not directly lead to fragmentation during oxidation,indicating that the pre-existing cracks in specimen are the key reason to pesting.The oxidation kinetics of the studied NbSi_(2) specimens corresponds well with the in-situ observation.
