温度对2519A铝合金高应变速率下动态屈服应力及显微组织的影响  

Effect of Temperature on Dynamic Yield Stress and Microstructure of 2519A Aluminum Alloy at High Strain Rate

作　　者：高志国[1] 张新明[1] 陈明安[1] 赵一生[1,2] 李惠杰[1] 刘波[1] 

机构地区：[1]中南大学,湖南长沙410083 [2]深圳职业技术学院,深圳518055

出　　处：《稀有金属材料与工程》2009年第5期881-886,共6页Rare Metal Materials and Engineering

基　　金：国家重点基础研究发展规划资助项目(2005CB623706)

摘　　要：采用分离式霍布金森(SHPB)压杆装置进行2519A-T87铝合金动态压缩试验,获得温度T为293、423、573、723K,名义应变速率ε为(1250±100)、(2400±100)、(5600±220)、(7050±100)s-1条件下2519A铝合金动态屈服应力σs-T关系曲线,并利用TEM对293和723K2个温度条件下压缩试样中析出相演变进行显微组织观察。分析研究了不同ε条件下T对试样σs和微观组织的影响规律。结果表明:在573K,5610s-1下2519A铝合金经受高应变速率冲击后组织中出现明显的绝热剪切带组织。由于2519A铝合金材料具有动态应变时效特性,导致Portevin-LeChatelier效应产生。当加载T一定时,ε越高,冲击后材料内部位错密度越高,致使σs越高;当加载ε一定时,加载T越高,材料软化效应越明显,σs下降越显著。高ε条件下,材料的显微组织产生显著变化,θ′析出相增厚效应严重,在723K下ε为5380s-1冲击时,θ′析出相部分会转变为长方体状相;当ε达到6950s-1时,θ′析出相完全转变为不共格相。The dynamic compression test of 2519A-T87 aluminum alloy was conducted at the temperature of 293,423, 573 and 723 K at the nominal strain rate of （1250±100）, （2400±100）, （5600±220） and （7050±100） s^-1 by split Hopkinson pressure bar（SHPB）, the curves of dynamic yield stress versus temperature were obtained. The microstructure for precipitate evolution in the compression specimens at the temperature of 293 and 723 K was observed by means of transmission electron microscopy （TEM）. The effects of temperature on dynamic yield stress and the microstructure were analyzed at different ε. An adiabatic shear band in 2519A alloy impacted at 573 K at the strain rate of 5610 s^-1 was observed. Under the condition of constant temperature, Portevin-Le Chatelier effect occurred owing to 2519A characteristic of dynamic strain aging. The higher the strain rate was, the higher the dislocation density in specimens and the dynamic yield stress of 2519A-T87 at the constant temperature were. At the constant ε, the higher the temperature was, the softer the specimen and the lower the dynamic yield stress of 2519A-T87. The thickening effect of θ＇ phase was very explicit with increasing of temperature at a high strain rate. A part of the θ＇ phase in specimens impacted at 723 K at the strain rate of 5380 s^-1 was changed into rectangle phases and all of them were changed into incoherent phase until the strain rate of 6950 s^-1.

关 键 词：2519A铝合金 动态屈服应力 高应变速率 温度 显微组织 

分 类 号：TG115.53[金属学及工艺—物理冶金]