| The application of magnesium alloys on dustries is creasing in recent years, so it’s urgently need to develop an alternative new heat-resistant wrought magnesium alloy for steel and aluminu m products. This paper is on the basis of Mg-5Sn alloy, using vacuum induction melting method to prepare Mg-5Sn-xZn(x = 0, 1, 2, 3; wt.%) alloys with different Zn content. The microstructure of as-cast, as- homogenized and deformed alloys, including the grain size and the content, size and distribution of second phase, were investigated with X-ray fluorescence spectrometer(XRF), X-ray diffractometer(XRD), optical microscopy(OM), scanning electron microscopy equipped with an INCA Energy 350 energy dispers ive X-ray spectrometer(SEM- EDS) and transmission electron microscopy(TEM); the mechanical properties were measured by tensile tester. To explore the plastic deformation capacity of Mg-Sn-Zn alloy through the analysis of the microstructure and mechanical properties.The microstructure of as-cast and as-homogenized Mg-5Sn-xZn(x=0, 1, 2, 3) alloys were investigated, the alloy were made of α-Mg matrix and Mg2 Sn phase. Zn element addition can refine the dendrite, reduce the secondary dendrite spacing and increase Mg2 Sn phase, but Mg2 Sn coarsed from particulate to intermittent mesh. The solubility of Sn in α-Mg matrix varies of Zn content, high content of Sn in liquid phase can hinder the diffusion of Mg atoms, which hinder the growth of grains. After homogenization treatment, a large number of small Mg2 Sn dissolved in the matrix, but there are still some large Mg2 Sn particle phase presenting o n the grain boundaries.The microstructure and mechanical properties of Mg-5Sn-xZn(x = 0, 1, 2, 3) alloys after hot extruded, hot rolled and cold rolled. Incomplete dynamic recrystallization occurres in as-extruded alloys, recrystallized fraction increases with increasing Zn content, and precipitated phase Mg2 Sn increases. Basal texture in ED-TD plains are weaken and strength and plasticity are increased. As-rolled alloys have undergone full dynamic recrystallization, grains are refined with small difference,(0002) base texture is enhanced with the increase of Zn content and stronger than as-extruded alloys, the strength of alloys increased with Zn content increases firstly, but the strength decreased when the Zn content is added to 3%. The strength of as-annealed alloys after hot-rolled decrease but plasticity increase significantly. Cold rolled alloys also occurres incomplete recrystallization, and Zn-containing alloys own higher strength and ductility after annealed.The microstructure and mechanical properties of Mg-5Sn-xZn(x = 0, 1, 2, 3) sheets after hot-rolled by ordinary way, cross-rolling and cold-rolled. Incomplete dynamic recrystallization occurs in alloys after hot extrusion, recrystallized fraction increases with increasing Zn content, and grains in board, horizontal, vertical plains have gradually become more uniform, moreover, precipitated phase Mg2 Sn increase, basal texture in ED-TD planes are enhanced significantly, the strength and plasticity of 0 °, 45 ° and 90 ° directions are ele vated, the anisotropy of mechanical properties are weakened. After ordinary hot rolling, the alloy is completely dynamic recrystallization, grain becomes uniform and fine, a lot of twins are found in Mg-5Sn-3Zn alloy, the basal texture are enhanced with the Zn content increases, and stronger than as-extruded alloys, the strength and ductility of the alloy increases at the same time. Grains in cross-rolling alloys are more uniform than ordinary hot-rolled alloys, more twins are presented in Zn-containing alloys gradually, the basal texture of Mg-5Sn sheet is enhanced, but Mg- 5Sn-3Zn alloy is weakened and weaker than ordinary hot-rolled alloys, the strength of the alloys increases with the Zn content increased, but plasticity increases firstly, then decreases when Zn content is 3%. Grain size in as-annealed alloy after cold-rolled grows up, and the the trend of mechanical properties is consistent with cross-rolling alloys. |
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