Effect of Er,Zr and Heat Treatment on Microstructure and Mechanical Properties of High Zinc Aluminum Alloy
Al-30Zn-3Cu-2.5Si high Zn Al-based alloy was taken as the research object,the effects of Er and Zr on the microstructure and mechanical properties of as-cast and heat-treated alloys were investigated,and the action mechanism was analyzed and discussed.The results show that the grain size of the alloy can be obviously refined by adding 0.10wt％ Er and 0.10wt％ Zr,the average grain size is reduced from 74.28 μm to 60.01 μm,and the grains of a-Al are changed into fine equiaxed grains.The addition of rare earth elements Er and Zr can form fine particles of Al3(Er,Zr)in the alloy and pin dislocations to improve the mechanical properties of the alloy.After adding Er and Zr,the tensile strength of as-cast alloy increases from 323.01 MPa to 358.29 MPa,which increases by 10.93％;the yield strength increases from 309.33 MPa to 315.00 MPa,which increases by 1.83％;the elongation barely changes.The tensile strength and yield strength of the alloy strengthened by solution-aging heat treatment are 449.48 and 408.51 MPa,which are 25.45％and 29.68％higher than those of the as-cast alloy,respectively.The coarse second phase exists at the grain boundary,which results in the poor elongation of the alloy.
high zinc aluminum alloyrare earth elementsheat treatmentmicrostructuremechanical properties
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