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利用差示扫描量热法(DSC)研究了2139铝合金在时效过程中的相变行为和析出序列,并测试了合金不同状态下的硬度及电导率,利用透射电镜(TEM)研究了合金的微观组织特征。结果表明:2139合金在时效过程中,随着温度的升高,DSC曲线上出现3个放热峰,其峰值温度分别为171,230和276℃,分别对应着合金中的3个析出过程,即Cu原子的偏聚形成GP,Ω相在{111}A l面上的析出和θ′/θ相在{001}A l的析出过程。合金的时效析出序列为:αsss→GP zone,Mg-Ag cluster→Ω相→θ′相→θ相。在时效初期,由于固溶原子脱溶而降低了晶格畸变程度,从而使得电导率略有降低,而后随着时效温度的升高,析出相的数量和种类也越来越多,电导率逐渐升高;合金的硬度随着时效温度的升高而升高,但当温度达到330℃时,由于析出相发生粗化和长大而导致硬度降低。
The phase transition behavior and precipitation sequence of 2139 aluminum alloy during aging were investigated by differential scanning calorimetry (DSC). The hardness and electrical conductivity of 2139 aluminum alloy were tested under different conditions. The effects of the alloy Microstructure characteristics. The results show that there are three exothermic peaks on the DSC curve of 2139 alloy during aging, with peak temperatures of 171, 230 and 276 ℃, respectively, corresponding to three precipitation processes in the alloy, namely Cu The segregation of atoms forms the GP, the precipitation of the Ω phase on the {111} A l plane and the precipitation of the θ ’/ θ phase at {001} A l. The aging precipitation sequence of the alloy is: αsss → GP zone, Mg-Ag cluster → Ω phase → θ ’phase → θ phase. At the initial stage of aging, the degree of lattice distortion is reduced due to the desolventizing of the solute atoms, resulting in a slight decrease of the conductivity. With the increase of the aging temperature, the number and type of precipitates are also increasing, and the conductivity gradually increases The hardness of the alloy increases with the aging temperature, but when the temperature reaches 330 ℃, the hardness decreases due to the coarsening and growth of the precipitated phase.