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耿振博,李双明,钟宏,胡锐,刘毅,罗锡明.单晶铱纳米压痕下位错形核与形变研究[J].稀有金属材料与工程(英文),2018,47(1):255~260.[Geng Zhen bo,Li Shuang ming,Zhong Hong,Hu Rui,Liu Yi,Luo Xi ming.Dislocation nucleation and room temperature deformation of single crystal Iridium[J].Rare Metal Materials and Engineering,2018,47(1):255~260.]
Dislocation nucleation and room temperature deformation of single crystal Iridium
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Received:November 26, 2015  Revised:January 14, 2016
Key words: Ir  single crystal, nano  indentation, heterogeneous  nucleation, dislocation  density
Foundation item:国家自然科学基金资助(项目号:U1202273和51501075)
Author NameAffiliationE-mail
Geng Zhen bo 西北工业大学凝固技术国家重点实验室 gengzb90@163.com 
Li Shuang ming 西北工业大学凝固技术国家重点实验室 lsm@nwpu.edu.cn 
Zhong Hong 西北工业大学凝固技术国家重点实验室  
Hu Rui 西北工业大学凝固技术国家重点实验室  
Liu Yi 昆明贵金属研究所  
Luo Xi ming 昆明贵金属研究所  
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      The brittle of Ir single crystal in nature has attracted more attention due to the fact that Ir is a FCC metal. In this paper, nanoindentation experiments were performed on the (100) and (110) planes of Ir single crystal. The results show that the dislocation activation volumes of Ir single crystal were calculated to be 1.09 ?3、1.23 ?3 for the (100) and (110) planes based on the first pop-in data from load-displacement curves. These results clearly demonstrate that the formation of dislocation is probably nucleated heterogeneously from point-like defects, while for the homogeneous nucleation, the activation energy should reach 60.57eV, and the activation radius reaches 1.971nm. In the plastic deformation of Ir single crystal, the deformation dislocation density was found to be the order of 1014m-2, which agrees with the previously reported data, implying that the anomalously high dislocation density does not exist in this nanoindentation experiment. The brittle fracture of Ir in nature may be attributed to the extremely small dislocation activation volume, leading to a large number of dislocation sources, and eventually caused by severely dislocation interaction.