The grain size effect and behavior of ion irradiation induced cavities in SA-Tyrannohex all fiber SiC composite under high temperature environments

• Main Authors: Hu, Jun-Fu, 胡均輔
• Other Authors: Kai, Ji-Jung
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/08563153696101994043

碩士 === 國立清華大學 === 工程與系統科學系 === 103 === Silicon carbide compoiste is a promising material for first wall and blanket components in fusion reactors due to the great strength and low radioactivity under high temperature environment. Besides, several studies have shown that nanocrystalline materials can enhance the irradiation tolerance by enhancing defects recovery via interfaces and grain boundaries. However, it is not for sure that the realationship of small grian size SiC can suppress the cavities formation or not. Furthermore, the detail of grain size effect on irradiation induced defects should be understood. In this work, SA-Tyrannohex all fiber SiC composite was irradiated by Si2+ single beam ,He+ single beam that the helium accmulation concentration up to 45000appm and Si/He dual beam condition. All of the iradiation condition were conducted at high temperature environment(>1073K).The microstructure evolution of irradiated SiC was examined by transmission electron microscopy. Cavities can be observed in dual beam irradiated SA-Tyrannohex SiC composite specimens and 45000appm He implanted specimens. Comparison to single crystal SiC, CVD polycrystalline SiC and CVI polyctstalline SiC irradiated in the same condition ,SA-Tyrannohex all fiber SiC appears to have excellent radiation tolerance under high temperature condition by suppressing the cavities formation.Besides, grain boundaries seems to hava a capability to enhance the point defects recombination.