Effect of heat treatment time on mechanical properties and microstructure of Al-4.8Cu-1.8Zn-1Ti-0.6Mg alloy
Firstly,the new Al-4.8Cu-1.8Zn-1Ti-0.6Mg alloy was subjected to solution treatment at 530℃ for different time and artificial aging at 165℃ for different time,followed by natural aging treatment for different time.The mechanical properties and microstructure of the alloy treated with different processes were studied using an electronic universal testing machine and scanning electron microscopy.The results show that the tensile strength,yield strength and elongation of the new Al-4.8Cu-1.8Zn-1Ti-0.6Mg alloy after solution treatment at 530℃ for 8 h and artificial aging at 165℃ for 3 h are 387.72 MPa,245.54 MPa and 9.8%,respectively.After natural aging for 15,75 and 135 days,the tensile strength of the alloy is 422.97,390.09 and 387.72 MPa,respectively,and the elongation is 5.03%,8.4%and 9.8%,respectively.It can be seen that as the natural aging time increases,the tensile strength of the alloy decreases,and the elongation increases,ultimately tending to stabilize.After heat treatment,there are three types of second phase in the alloy,among which the coarse precipitation of bright silver θ(Al2Cu)phase at grain boundaries leads to a decrease in the tensile strength of the alloy,while the dark gray Al3 Ti phase is prone to aggregation,and the aggregated coarse Al3 Ti phase leads to the decrease in the deformation ability of the alloy.
Al-4.8Cu-1.8Zn-1Ti-0.6Mg new alloyheat treatment timemechanical propertymicrostructurefracture surface morphology