Effect of pre-stretching and aging treatment on microstructure and mechanical properties of extruded Mg-Gd alloy
Effect of different pre-stretching amounts(0%,5%and 10%)and aging treatment on microstructure and mechanical properties of extruded Mg-4Gd alloy was studied by means of optical microscope,scanning electron microscopy and universal tensile testing machine.The results indicate that increasing the pre-stretching amount will increase the number of second phases with irregular polyhedral structures and relatively low Gd content formed during the aging process,and their size will increase with the increase of aging time.When the pre-stretching amount increases from 0%to 5%and 10%,the strength of the alloy continuously increases,but the increment gradually decreases,and the elongation first rapidly decreases and then stabilizes.The combination of pre-stretching treatment and aging treatment can improve the strength of the alloy but reduce the elongation.Among them,the yield strength of the alloy with pre-stretching of 10%under peak aging process is increased to 136.29 MPa,the tensile strength is increased to 241.48 MPa,and the elongation is reduced to 12.49%.Compared with pre-stretching treatment,the value of hardening ability and work hardening index of the alloy after aging treatment decrease.The work hardening rate of alloys is mainly affected by the pre-stretching process,but can be effectively controlled through subsequent aging treatment.
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