Effect of solution and aging system on microstructure and mechanical properties of 7000 series aluminum alloy produced by powder metallurgy

Abstract

Different solid solution treatments (G1, G2, G3) and aging treatment were performed on the 7000 series aluminum alloy prepared by powder metallurgy (PM). The phase analysis and microstructure observation of the alloy material were carried out using metallographic microscope (MM), x-ray diffraction (XRD) analyzer and scan electron microscope (SEM). Hardness, electrical conductivity and the compressive mechanical properties of the alloy were measured. The results show that the size and quantity of the undissolved phase in the 7000 series aluminum alloy gradually decrease with the increase of the highest temperature of solid solution and the total solid solution time. When the highest temperature of solution rises to 470 °C (G2), the amount of undissolved phase in the alloy decreases slowly; As the solid solution temperature increases, the hardness of the alloy gradually increases under the aging treatment at 121 °C. The alloy under G3 solid solution has the highest hardness after 15 h aging, and the peak value is 227.5HV. With the increase of solution temperature, the electrical conductivity of aluminum alloy decreases gradually after aging. With the increase of solid solution temperature and solid solution time, the compressive strength value of the alloy after the aging increases first and then decreases. The compressive strength of alloy under G2 solid solution process reaches a maximum of 675.15 MPa, and its fracture strain is 7.73%.