7B04铝合金的时效沉淀析出及强化行为Ageing precipitation and strengthening behavior of 7B04 aluminum alloy

利用差示量热法(DSC)、透射电镜(TEM)、选区电子衍射(SAED)、常规力学性能测试等手段研究了7B04铝合金时效沉淀析出及强化行为。结果表明：该材料存在显著的自然时效现象，大量的GPⅠ区沉淀析出是自然时效强化的主要原因；合金在120 ℃进行人工时效的初期析出大量GP区，使材料的强度迅速提高，时效8 h后，其横向极限抗拉强度即可达到570 MPa，时效22 h时可达强度峰值点，此时GP区(包括GPⅠ和GPⅡ区)和η′相是主要强化相；峰值时效后继续延长时效时间，材料的强度无明显降低，极限抗拉强度保持在590 MPa左右。

The ageing precipitation and strengthening behavior of 7B04 aluminum alloy were investigated by DSC, TEM, HREM, SAED and tensile testing techniques. The results show that increment of strength during natural ageing at room temperature is related to the dominant formation of GPI zones. During the early stage of artificial ageing at 120 ℃, the strong age-strengthening response is due to the precipitation of GP (both GPI and GPII) zones. The peak UTS value is achieved as 570 MPa after ageing at 120 ℃ for 22 h, both GP (GPⅠ and GPⅡ) zones and η′ phase are major precipitates at this stage. After 22 h, the tensile strength changes little (approximate by at 590 MPa) for a relative long time.

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