(1. 燕山大學(xué) 機(jī)械與工程學(xué)院，秦皇島 066004；
2. 北京航空材料研究院，北京 100095)
摘 要: 研究室溫大氣環(huán)境下2E12鋁合金微觀組織與疲勞裂紋擴(kuò)展行為之間的關(guān)系，并分別利用光學(xué)顯微鏡、透射電鏡和掃描電鏡對合金的微觀組織及疲勞斷口進(jìn)行分析。結(jié)果表明：合金的疲勞裂紋擴(kuò)展速率與合金中微米級第二相粒子的體積分?jǐn)?shù)成正比，且隨著亞微米級第二相粒子尺寸的增加及晶粒尺寸的減小，合金的疲勞裂紋擴(kuò)展速率明顯降低，尤其是在Pairs區(qū)及以后，其值降低30%；在低速擴(kuò)展區(qū)，合金斷口呈現(xiàn)脆性的準(zhǔn)解理斷裂特征，在中速擴(kuò)展區(qū)，合金出現(xiàn)清晰的疲勞條紋。
關(guān)鍵字: 2E12鋁合金；疲勞裂紋擴(kuò)展；晶粒；微米級第二相；亞微米級第二相
（1. School of Mechanical Engineering, Yanshan University, Qinhuangdao 066004, China;
2. Beijing Institute of Aeronautical Materials, Beijing 100095, China）
Abstract:The interrelationship between microstructure and fatigue crack propagation behaviors of 2E12 aluminum alloys was investigated at room temperature in air. The microstructures and fatigue fracture surfaces of the alloy were examined by optical microscopy, transmission electron microscopy and scanning electron microscopy. The results show that the fatigue crack growth rate is proportional to the volume fraction of micro-sized second-phase particles. And with the increase of submicro-sized second-phase particles size and the decrease of grain size, the fatigue cracks propagate much slowly, reducing by 30% or more at Pairs region. In a low fatigue crack growth rate region, alloy shows quasi-cleavage fracture features. In a middle fatigue crack growth rate region, the fatigue striation features are clear.
Key words: 2E12 aluminum alloy; fatigue crack propagation; grain; micro-sized second-phase particles; submicro-sized second-phase particles
