Visualization of crack-grain boundary interaction in transparent crystals

1997 Fiscal Year Final Research Report Summary

• Project/Area Number: 08650770
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Physical properties of metals
• Research Institution: KYUSHU UNIVERSITY
• Principal Investigator: HIGASHIDA Kenji Kyushu University., Faculty of Engineering, Associate Professor, 工学部, 助教授 (70156561)
• Co-Investigator(Kenkyū-buntansha): MORIKAWA Tatsuya Kyushu University., Faculty of Engineering, Research Associate, 工学部, 助手 (00274506) ; ARAMAKI Masatoshi Kyushu University., Faculty of Engineering, Research Associate, 工学部, 助手 (50175973) ; ONODERA Ryuta Kyushu University., Faculty of Engineering, Professor, 工学部, 教授 (40038021)
• Project Period (FY): 1996 – 1997
• Keywords: Fracture / Crack / Grain boundary / Ionic crystal / Dislocation / Shielding

Research Abstract

Crack propagation behavior and its related phenomena in NaCl transparent bicrystals have been investigated by using photoelastic method and etch-pit technique. Crack extension took place on the {001} cleavage plane, and matny slip bands were formed along the {011} slip plane before and during the crack extension. When the crack tip came closer to the grain boundary, crack extension became slower and the threshold stress intensity factor for crack extension KIC^<**> increased. Etch pits observation indicated that the dislocation density around the crack tip became higher near the boundary. The effect of grain boundary on such behavior of crack extension is discussed from the viewpoint of crack tip shielding due to dislocations.