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通过扫描电镜(SEM)、差热分析(DSC)、电子探针(EPMA)、波谱分析(WDX)和X射线衍射等方法,研究了2524铝合金铸锭均匀化过程中的组织演变。结果表明:合金铸锭由枝晶和非平衡相组成;300℃以上均匀化时,晶粒内析出大量的弥散相,延长保温时间,弥散相尺寸变大,分布逐渐变均匀;随着均匀化温度升高,非平衡相逐渐溶解、球化,残余相为Al12Cu Mn2,残余相周围存在PFZ,其形成机制为贫溶质机制;不同冷却方式影响合金的最终组织,冷却速度较快时析出相细小弥散,冷却速度较慢时晶界和晶内有粗大S相形成。
The microstructure evolution of 2524 aluminum alloy ingot during homogenization was studied by means of SEM, DSC, EPMA, WDX and XRD. The results show that the alloy ingot is composed of dendrites and non-equilibrium phases. When the temperature is above 300 ℃, a large amount of disperse phase precipitates in the grains and the holding time prolongs. The size of disperse phase becomes larger and the distribution becomes more homogeneous. With the homogenization temperature And the non-equilibrium phase gradually dissolves. The spheroidized and residual phases are Al12Cu Mn2 and the PFZ exists around the residual phase. The mechanism of formation is lean solute mechanism. Different cooling modes affect the final microstructure of the alloy. When the cooling rate is faster, , When the cooling rate is slow, grain boundary and intragranular S phase are formed.