Effect of 0.3wt％Si addition on the microstructure and mechanical properties of Al-1.5Cu-0.7Mg alloy was studied by means of mechanical test,resistivity test at 20 ℃ and microstructure observation.The results show that with the 0.3wt％Si addition,the as-aged strength of the tested alloy is obviously increased.After peak aging at 473-493 K,its 20 ℃ resistivity is 3.638-3.667 μΩ·cm,and its tensile strength is 370-380 MPa,and then the relationship between the 20 ℃ resistivity and the relative volume fraction of the second phase precipitated during aging is established according to Matthiessen rule.The second phase precipitation activation energies in aging of the Al-1.5Cu-0.7Mg and Al-1.5Cu-0.7Mg-0.3Si alloys obtained by using JMA(Johnson-Mehl-Avrami)equation are 135 kJ/mol and 204 kJ/mol respectively,according to which to know that the S"phase is dominant in the Al-1.5Cu-0.7Mg alloy and the S phase is dominant in the Al-1.5Cu-0.7Mg-0.3Si alloy.The resistivity under other aging parameters is also predicted by JMA equation,and the accuracy of the prediction model is all over 99％.
Al-1.5Cu-0.7Mg alloySiresistivitytensile strengthsecond phaseprecipitation activation energy
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