Abstract：7075 aluminum alloy bar was prepared by powder hot extrusion method. The microstructures of the alloy bar were examined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). In addition, the tensile properties of the samples were also tested. The influences of the extrusion ratio on the microstructure and mechanical properties of the bar were investigated, and the strengthening mechanism was calculated in theory. The results show that a large number of second phase MgZn2 precipitates are desolventized and precipitated during hot extrusion at 500 ℃ with extrusion ratios of 9, 16, 25, and 36. With increasing extrusion ratio, the metallurgical bonding between the powder particles becames more sufficient, and the tensile strength and elongation of the alloy increase continuously. A high tensile strength of 492 MPa with an elongation of 27.6% is obtained at an extrusion ratio of 36. The fracture mode is a ductile-brittle-bonding fracture. The strengthening mechanism is the combined action of fine-grain strengthening, dislocation strengthening, second phase strengthening and solution strengthening.
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2022, Vol. 27 
