(1. 西北工業(yè)大學 航空學院，西安 710072；
2. 西北工業(yè)大學 凝固技術(shù)國家重點實驗室，西安 710072)
摘 要: 利用INSTRON準靜態(tài)試驗機和分離式Hopkinson壓桿系統(tǒng)對鑄造鎂合金AZ91在不同應變率下進行壓縮試驗，研究AZ91鎂合金在高應變率范圍內(nèi)(應變率6×102~1×104 s−1)的動態(tài)力學行為，并利用掃描電鏡觀察試樣在不同應變率下破壞斷口微觀形貌的變化，探索應變率對破壞機理的影響。結(jié)果表明：室溫下鑄造鎂合金AZ91具有明顯的應變硬化性質(zhì)；在準靜態(tài)壓縮過程中材料對應變率負敏感，當應變率達到7×103 s−1時，AZ91鎂合金表現(xiàn)出明顯的應變率敏感性；在準靜態(tài)破壞和動態(tài)破壞下，材料斷口的微觀形貌具有很大不同。
關(guān)鍵字: AZ91鎂合金；應變硬化；動態(tài)壓縮；斷口分析
cast magnesium alloy AZ91
（1. School of Aeronautics, Northwestern Polytechnical University, Xi’an 710072, China;
2. State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China）
Abstract:The mechanical behavior of cast AZ91 under a wide range of strain rates (10−3−104 s−1) was described by using INSTRON testing system and Split Hopkinson Pressure Bar. The dynamic behavior (strain rate 6×102−1×104 s−1) of AZ91 was studied. The fracture surface of samples at different strain rates was examined by scanning electron microscope (SEM). The results show that the cast AZ91 has obvious strain hardening character at room temperature. The mechanical behavior of cast AZ91 declines as the strain rate increases under a low strain rate range (10−3−10−1 s−1). When the strain rate exceeds 7×103 s−1, the cast AZ91 shows strong strain rate sensitivity. And the microstructure of the sample’s fracture surface exits great difference under different strain rates.
Key words: magnesium alloy AZ91; strain hardening; dynamic compression; fracture analysis
