Effect of pressures on macro-/microstructures and mechanical properties of A380 aluminum alloy
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摘要: 對A380鋁合金進行了擠壓鑄造成型和傳統重力鑄造成型,并制得試樣.采用偏光顯微鏡、掃描電鏡、定量金相分析、拉伸性能測試等手段,研究在不同壓力下擠壓鑄造A380鋁合金的鑄造組織和力學性能.結果表明:當壓力在0~75 MPa范圍內時,隨著壓力的增加,一次枝晶臂尺寸和氣孔率得到大幅下降,共晶組織體積分數增加;二次枝晶臂間距減小;針狀富鐵β-Al5 FeSi相尺寸大幅度減小,同時有部分漢字狀α-Al8(Fe,Mn)3Si2相生成.當壓力在75~100 MPa范圍內時,壓力繼續增加對合金組織細化、第二相形貌改善和力學性能提高的作用不明顯.擠壓鑄造試件與重力鑄造試件相比,氣孔率減小,顯微組織細化,力學性能顯著提高.當壓力為75 MPa時,擠壓鑄造A380鋁合金的鑄態抗拉強度和伸長率分別比重力鑄造提高19%和65%.Abstract: This study investigated the microstructures and the mechanical properties of the A380 alloy solidified at different squeeze pressures by polarizing microscopy, scanning electron microscopy, image analysis, and tensile test. The obtained results show that the microstructures of the squeeze casting specimens are much finer than those of gravity casting specimens. Moreover, the porosity and the mechanical properties of the squeeze casting specimens are remarkably improved compared with those of the gravity casting specimens. The size of the dendrite arm and the porosity decrease when the squeeze pressure is increased from 0 MPa to 75 MPa in the squeeze casting process. The eutectic volume fraction of the specimen increases, while the secondary dendrite spacing decreases. The size of the needle-like β-Al5 FeSi phase significantly decreases. In addition, a few α-Al8 (Fe,Mn)3Si2 phases with Chinese characters are observed in the grain boundary. The influence of the pressure on the microstructures, second-phase morphology, and mechanical properties of the squeeze casting specimens does not significantly improve with the increasing squeeze pressure when the squeeze pressure is larger than 75 MPa. The tensile strength and the elongation of the A380 alloy when the squeeze pressure is 75 MPa increase by 19% and 65%, respectively, compared with those of the gravity casting specimens.
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Key words:
- A380 aluminum alloy /
- squeeze casting /
- microstructures /
- mechanical property
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參考文獻
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