【摘要】 在扫描电镜上利用ＨＸ－ＴＳ２型拉伸台，对ＬＣ４高强铝合金常规热处理状态Ｔ６（时效至峰值强度）及退火状态拉伸时微裂纹的萌生及连接进行了原位动态观察。结果表明：在Ｔ６状态下，局部应力集中和应变引起的分散相（Ｐ）与基体（Ｍ）界面的分离及其本身开裂是微裂纹萌生的主要机制。退火样品除Ｐ／Ｍ界面分离和大块脆性相解理外还出现大量弯曲和扭折的滑移带。两种样品微裂纹的连接方式也不尽相同更多还原

【Abstract】 Using the HX TS2 tensile stage mounted on a SEM electron microscope,an in situ observation of microcrack nucleation,propagation and coalescence in tensile state for LC4 high strength aluminium alloy treated to both T6 and annealing conditions has been investigated in this paper.It is shown that for T6 temper sample the main mechanisms of nucleation of tensile microcracks are the decoherence between inclusive particles and matrix and the cracking of the particles due to local stress and strain concentration,while for the annealed sample,besides the mechanisms mentioned above the nucleation of microcracks also relates to many twisted slip bands.The modes of microcrack coalescence are different because of different strength and plasticity of matrix for the two samples.更多还原