升温轧制调控Mg-Sn-Zn-Ca合金第二相及其性能研究

Regulation of Secondary Phases in Mg-Sn-Zn-Ca Alloys Through Incremental Temperature Rolling and Their Performance

摘要:

为了探讨第二相对Mg-Sn-Zn-Ca合金微观结构及力学性能的影响，本研究通过等温轧制与升温轧制2种方式处理了Mg-2Sn-2Zn-1Ca镁合金板材。力学性能测试表明，等温轧制板材中部的屈服强度（161.3 MPa）和延伸率（6.6%）显著低于升温轧制板材（295.6 MPa，20.9%）。微观分析揭示，等温轧制板材呈现粗大晶粒结构，并伴有大量形变孪晶；而升温轧制通过第二相调控将晶粒细化至10.17 μm。在等温轧制过程中，随着第二相（Mg_xZn_y）含量的增加，较大的颗粒尺寸引起了应力集中，进而导致材料的早期失效；而在升温轧制过程中，较高的温度促进了第二相与高密度位错区之间的相互作用，这些区域成为再结晶过程中的优先形核点，从而增强了材料的可塑性。

Abstract:

To investigate the effect of secondary phases on the microstructure and mechanical properties of Mg-Sn-Zn-Ca alloys, this study employed both isothermal and incremental temperature rolling processes on Mg-2Sn-2Zn-1Ca magnesium alloy sheets. Mechanical tests reveal that the yield strength (161.3 MPa) and elongation (6.6%) of the isothermally rolled sheet are significantly lower than those of the incremental-temperature-rolled sheet, which exhibits a yield strength of 295.6 MPa and an elongation of 20.9%. Microstructural analyses indicate that the isothermally rolled sheet exhibits a coarse-grain microstructure with a large number of deformation twins. In contrast, the incremental temperature rolling process effectively decreases the grain size to 10.17 μm through the regulation of secondary phase. During isothermal rolling, an increase in the content of secondary phases (Mg_xZn_y) leads to larger particle sizes, which induces stress concentration, thereby contributing to premature material failure. Conversely, incremental temperature rolling facilitates interactions between secondary phases and high-density dislocation regions, acting as preferential nucleation sites during recrystallization, and thereby enhancing the plasticity of the material.