(1. 福州大學(xué) 材料科學(xué)與工程學(xué)院，福州 350002；
2．浙江大學(xué) 材料科學(xué)與工程系， 杭州 310027)
摘 要: 采用透射電鏡動態(tài)拉伸、 原位觀察研究了低層錯能合金H68黃銅斷裂的微觀過程。 結(jié)果發(fā)現(xiàn)： 黃銅薄膜試樣拉伸時， 裂尖首先發(fā)射位錯， 平衡時形成無位錯區(qū)和反塞積位錯群； 裂尖前方較厚區(qū)域可以發(fā)生孿生變形，形成形變孿晶， 微裂紋在孿晶中形核、 擴(kuò)展， 導(dǎo)致裂紋呈Z字形擴(kuò)展； 裂尖無位錯區(qū)也可能形成微孿晶， 微裂紋在微孿晶中形核，使裂紋呈不連續(xù)擴(kuò)展； 微裂紋也可以從主裂紋頂端連續(xù)形核、 擴(kuò)展。
關(guān)鍵字: 斷裂； 無位錯區(qū)； 形變孿晶； 黃銅
fracture of H68 brass
（1. School of Materials Science and Engineering,
Fuzhou University, Fuzhou 350002, China;
2. Department of Materials Science and Engineering,
Zhejian University, Hangzhou 310027, China）
Abstract:The micro process of crack initiation and propagation in H68 brass with low stock fault energy was observed by in situ tensile test in TEM. The results show that many dislocations are emitted from a loaded crack tip and move forward. A dislocation free zone(DFZ) is formed between crack tip and the inversely pile-up dislocations when the dislocation emission and motion reach equilibrium. Mechanical twin forms in the thicker area ahead of crack, and then the micro-crack initiates and propagates in the mechanical twin, which result in a zig-zag crack propagation. The micro-twin forms in the DFZ and the micro-crack initiates in the micro-twin, resulting in the crack propagation discontinuously. Sometimes the micro-crack propagates from a blunted crack tip continuously.
Key words: fracture; dislocation free zone; mechanical twin; brass
