变质处理和时效处理对Al8Si0.4Mg0.4Fe合金组织、力学性能及电导率的影响

Effect of Modification and Aging Treatments on Microstructure, Mechanical Properties and Electrical Conductivity of Al8Si0.4Mg0.4Fe Alloy

摘要:

对自主设计的Al8Si0.4Mg0.4Fe合金进行了Sr变质处理及固溶+时效处理，以调节其组织和性能。结果表明：变质处理后，合金的室温抗拉伸强度变化不大，断裂伸长率略有提高（1.82%至3.34%），电导率由变质处理前的40.1% IACS显著提高到42.0% IACS。将变质处理后的合金在515 ℃固溶处理8 h，然后在180、200、220和240 ℃时效处理6 h。随着时效温度的升高，材料的电导率由41.4% IACS单调增加到45.5% IACS，室温抗拉伸强度先升高后降低。在200 ℃时，合金的电导率与室温抗拉伸强度表现出良好的协调性，电导率为42.5% IACS，室温抗拉伸强度为282.9 MPa。当时效温度继续升高时，合金产生过时效现象。虽然电导率仍在上升，但室温抗拉伸强度急剧下降，在时效温度240 ℃时仅为177.1 MPa。

Abstract:

Self-designed Al8Si0.4Mg0.4Fe aluminium alloy was modified with Sr, followed by solid solution and aging treatments to regulate its microstructure and mechanical/electrical properties. The results show that after the modification treatment, the room-temperature tensile strength of the alloy remains nearly unchanged, the elongation at break slightly increases from 1.82% to 3.34%, and the electrical conductivity significantly increases from 40.1% international annealed copper standard (IACS) to 42.0% IACS. After the modification, the alloy was subjected to solid solution treatment at 515 ℃ for 8 h, followed by aging treatment at 180, 200, 220 and 240 ℃ for 6 h. With increasing aging temperature, the electrical conductivity increases monotonously from 41.4% IACS to 45.5% IACS, while the room-temperature tensile strength initially increases and then decreases. At 200 ℃, the alloy achieves an optimal balance between electrical conductivity and room-temperature tensile strength: the electrical conductivity is 42.5% IACS, and the room-temperature tensile strength is 282.9 MPa. When the aging temperature continues to rise, the alloy undergoes overaging. Although the conductivity continues to increase, the room-temperature tensile strength drops sharply, and it is only 177.1 MPa at 240 ℃.