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利用维氏硬度检测、疲劳性能测试、视差量热法(DSC)、透射电子显微分析(TEM)等手段,研究了航空用T3态2E12铝合金在150℃下分别暴露10 h,100 h,1000 h组织演变及疲劳寿命变化规律。结果表明:随热暴露时间的增加,合金硬度不断增大,疲劳寿命呈先增后降趋势;T3态及热暴露10 h合金中析出相由GPB区结构组成,热暴露10 h合金中GPB区发生长大,因而具有最长疲劳寿命;热暴露100 h至1000 h后,合金中析出相为S″相及S′相,析出相在晶界处析出,晶界附近形成无沉淀析出带(PFZ);由于S″相及S′相共格性较GPB区低,加之晶界处析出相易形成裂纹源,PFZ与基体协调性差等因素,热暴露100 h和1000 h后,合金疲劳寿命急剧下降。
Vickers hardness test, fatigue test, differential scanning calorimetry (DSC) and transmission electron microscopy (TEM) were used to investigate the effects of exposure on T3 state 2E12 aluminum alloy at 150 ℃ for 10 h, 100 h, Evolution of tissue evolution and fatigue life under 1000 h. The results show that with the increase of heat exposure time, the hardness of the alloy increases and the fatigue life increases first and then decreases. In the T3 state and the 10 h heat exposure, the precipitated phase consists of the GPB structure, and the GPB zone And the maximum fatigue life is appeared. After the thermal exposure for 100 h to 1000 h, the precipitated phase is S “phase and S ’phase in the alloy, and the precipitates are precipitated at the grain boundary and precipitate-free zone is formed near the grain boundary PFZ). Because of the lower lattice constants of S ”phase and S ’phase than the GPB region and the cracked sources formed at the grain boundary, the coordination between PFZ and the matrix is poor, the fatigue life of the alloy after 100 h and 1000 h of heat exposure A sharp decline.