The effect of continuous cooling process on aging microstructure and properties was investigated by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), electrical resistivity, hardness test and Monte Carlo simulation. The result show that the cooling precipitations areθ,θ′ andθ″ phases. The hardness and electrical resistivity are not monotone decrease with the extending of cooling ending time, since the different microstructures induced by different cooling processes.θ″ phase precipitated in cooling processes is acted as precursor ofθ′ phase, as a result, an earlier peak hardness value is observed. However, extremely slow cooling processes will lead to the significant consumption of alloy atoms, in which the driving force for aging precipitation decreases. The results of Monte Carlo simulation reveal that the decrease of residual solid solution will delay the formation of Cu rich clusters in the early stage of aging. If the residual solid solution is less than 2%, few clusters are observed after simulating aging for 1800s and which decreases the efficiency of aging hardening.%采用扫描电镜、透射电镜观察、选区电子衍射、电阻率测试、硬度测试和Monte Carlo模拟等方法,研究连续冷却对Al-4%Cu合金(质量分数)时效组织和性能的影响.结果表明,实验合金的连续冷却脱溶产物主要包括θ相、θ′相和θ″相,不同冷却条件形成的析出相组态会导致合金的硬度曲线、电阻率曲线不随冷却速率的降低而单调降低.冷却析出的θ″相作为时效强化相的前驱体能够加速时效强化相析出,导致合金的时效硬化曲线峰值时间提前,但是极慢的冷却条件消耗了大量的溶质原子,导致时效驱动力下降.Monte Carlo模拟表明,连续冷却脱溶导致的残余溶质质量分数降低会减慢Cu原子团簇的形成速率,当残余溶质质量分数低于2%时,模拟时效1800s合金中仍然不会出现明显的团簇,降低了时效强化效率.
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