7B04鋁合金的時效沉淀析出及強化行為Ageing precipitation and strengthening behavior of 7B04 aluminum alloy

利用差示量熱法(DSC)、透射電鏡(TEM)、選區(qū)電子衍射(SAED)、常規(guī)力學性能測試等手段研究了7B04鋁合金時效沉淀析出及強化行為。結果表明：該材料存在顯著的自然時效現象，大量的GPⅠ區(qū)沉淀析出是自然時效強化的主要原因；合金在120 ℃進行人工時效的初期析出大量GP區(qū)，使材料的強度迅速提高，時效8 h后，其橫向極限抗拉強度即可達到570 MPa，時效22 h時可達強度峰值點，此時GP區(qū)(包括GPⅠ和GPⅡ區(qū))和η′相是主要強化相；峰值時效后繼續(xù)延長時效時間，材料的強度無明顯降低，極限抗拉強度保持在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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