Papers by Author: Jing Huai Zhang

Abstract: The microstructure and tensile properties of the as-cast and as-extruded Mg-12Li-1Zn-xSn (x=1, 3, 5, 8, wt.%) alloys were investigated. The alloys are mainly composed of β-Li phase, Mg₂Sn phase. With the increase of Sn content, the microstructure of as-cast alloys is refined. After extrusion processing, grain size is obviously refined, and the Mg2Sn phase is broken into tiny particles. The elevated-temperature tensile behavior of the alloy was investigated at 373~523k under the strain rate of 1×10^-2~1.7×10^-4s^-1. The results indicate addition of Sn can improve the strength and plasticity, when the content of Sn is 5.0 wt.%, the as-extruded alloy possesses good superplasticity, which obtains the maximum elongation of 134.4% under a low strain rate of 1.0×10^-3s^-1 at 523K.

Abstract: Mg-4Al-6RE-0.3Mn (RE=La, Ce, Pr, Nd, wt.%) magnesium alloys were prepared successfully by the high-pressure die-casting technique. The microstructures and tensile properties in the temperature range from room temperature to 200 °C were investigated. It was confirmed that the Mg-Al-RE-based alloys exhibited an outstanding die-cast character. The cross-section of test bar could be divided into the fine skin region and the relatively coarse interior region by a narrow band with fine structure. Two binary Al-RE (RE=La, Ce, Pr, Nd) phases with the former being the dominant one, Al₁₁RE₃ and Al₂RE, occupied large grain boundary area. All the four alloys exhibited excellent tensile properties until 200 °C, which were mainly attributed to the fine grain size and the strengthening phase Al₁₁RE₃ with high volume fraction, fine acicular/lamellar morphology, "orderly stack” distribution and good thermal stability. The results of this work provided a basis for further investigation of the new heat-resistant high-pressure die-cast magnesium alloys designed to serve at temperature up to 200 °C.

Abstract: Several Mg-4Al-4La/Ce alloys were developed and their microstructure and mechanical properties were evaluated. The phase compositions of Mg-4Al-4La alloy consist of α-Mg and Al11La3 phases. While two binary Al-RE phases, Al11RE3 and Al2RE (RE=Ce/La), are formed in Mg-4Al-4Ce/La alloy, and Al11Ce3 and Al2Ce are formed in Mg-4Al-4Ce alloy. The optimal tensile properties are obtained in Mg-4Al-4Ce/La alloy, in which the UTS, YS and δ are 250, 149.2 MPa and 12.24% at room temperature, and 157.8, 116 MPa and 27% at 150oC, and 99.1, 118.2 MPa and 23.2% at 250oC, respectively. The mechanics properties of Mg-4Al-4Ce/La alloy are nearly same with commercial AE44. The compression creep is lower than that AJ62 alloy.