Papers by Author: Jun Wang

Abstract: Microstructures and mechanical properties of Mg-10Gd-3Y-2Zn-0.5Zr alloy were investigated. Three kinds of phases including Mg, Mg₃(GdYZn) and Mg₁₂(GdY)Zn were found in the as-cast alloy. Two different patterns of the long-period stacking order (LPSO) phases including lamellar structure and block-like structure were observed in the homogenized alloy and both of them were identified as the phase of Mg₁₂(GdY)Zn. After extrusion with ratio of 10:1 under 420°C, fine dynamic recrystallized grains were obtained and its average size was only about 4μm. The alloy exhibited excellent mechanical properties by hot extrusion and heat treatment. The ultimate tensile strengths of the as-extruded and peak-aged alloys were 415MPa and 480MPa, the tensile yield strength were 335MPa and 410MPa, the elongations were 16% and 13.5%, respectively. The high mechanical properties were mainly attributed to the combined effects of fine grains, LPSO phases and the dispersed precipitates.

Abstract: The effect of different hydrostatic extrusion ratios on the microstructure and mechanical properties of the ZK60 magnesium alloys were investigated. The results showed that, the major deformation mechanism of the alloy is twinning at room temperature, which resulted in that the tensile strengthen and hardness of the extruded alloy improved greatly. With deformation ratio increasing, the ultimate tensile strengthen and hardness are linearly increased, with the functions of Y= 4.2X+358.3 and Y=2.3X +73.69, respectively. And the maximum tensile strength and hardness of the extruded alloy are 383 MPa and 87HB, respectively. But the elongation decreases obviously, the minimum decreasing degree is 50%. With the deformation ratio increasing, the tendency of elongation rate increased as an “M” model.

Abstract: The extruded microstructure and properties of Mg-2.7Nd-1.2Gd-0.4Zn-0.3Zr alloy by squeeze casting were investigated. After aging process (T5), the dislocation density was enhanced and the dislocation interaction was increased; the factors of grain refinement, RE phases redistribution, the increment of dislocations and the interaction between dislocations and precipitate phases were contributed to the strength increase after hot extrusion and aging treatment, the fracture mode of the hot-extruded alloy was the fracture of the secondary phases and the trans-grain fracture.

Abstract: The effect of the combined action of hot work and heat treatment on the microstructure and mechanical properties of a Mg-2Gd-Nd-0.4Zn-0.3Zr (wt. %) (E21) alloy was investigated. Results showed that the solution treatment time of the ingot played a great effect on the mechanical properties of the extruded alloy. With solution treating time of the ingot increasing, the tensile strength of the extruded alloy decreased gradually, but the elongation increased greatly. The best combination of strength and ductility was achieved for the extruded alloy after the ingot solution treated at 520°C for 3 h, extrusion at 400°C and aging at 200°C for 16 h, namely ultimate tensile strength = 331MPa and elongation = 7.1%.