挤压镁合金的研究进展

Research Progress on Extruded Magnesium Alloys

镁合金因其优异的轻质性、较高的比强度和优良的可回收性等优点在汽车工业、3C产品、航天航空等领域有着广阔的应用前景。近年来,虽然挤压镁合金在市场的应用率稳步增长,但挤压镁合金的商业应用率与挤压铝合金的相比仍然有不小的差距,这主要是因为挤压镁合金的可挤压性差、拉伸-压缩屈服不对称、绝对强度低等问题限制了其商业发展。提高镁合金的强度和挤压效率能有效地扩大镁合金的商业化应用范围,而合金成分和热挤压工艺参数是影响挤压合金组织和性能的决定性因素。近年来,研究人员从合金化设计和挤压工艺方面着手,对挤压镁合金的微观组织和力学性能强化进行了深入研究,并取得了重要进展。本文简述了镁合金在挤压过程中出现热裂现象的原因、机理以及影响因素,概述了热挤压过程中合金微观组织的演变规律,总结了动态再结晶的形核机理和织构弱化的机制,讨论了挤压参数(挤压温度、挤压速率、挤压比)对挤压态合金性能的影响规律。从合金成分设计、合金体系方面详细地综述了近年来Mg-Al、Mg-Zn、Mg-Sn、Mg-RE系高强度挤压镁合金的研究进展,并且分析了高强度挤压镁合金的强化机理。根据目前挤压镁合金与挤压铝合金在性能上存在的差距,对挤压镁合金提出了新的合金设计思路和工艺路线,并展望了未来高性能镁挤压合金进一步的研究方向。

Magnesium(Mg)alloys have broad application prospect in the automotive industry,3C products,aerospace and other fields due to their lightweight,high specific strength,fine retrievability and other excellent characteristics.In recent years,although the application rate of extruded Mg alloy in the market has grown steadily,there is still a gap between extruded Mg alloy and extruded Al alloy on industrial application because of limits of commercial development resulting from poor extrudability,tension-compression yield asymmetry,low absolute strength,etc.Increasing the absolute strength and extrusion efficiency of Mg alloy can effectively expand the industrial application of magnesium alloy.The alloy composition and thermal processing parameters are the decisive factors affecting the microstructure and properties of the extruded alloy.In recent years,researchers have deeply studied the microstructure and mechanical properties of extruded Mg alloys from alloying design and hot extrusion process,and made important progress.The causes,mechanism and influencing factors of hot cracking of Mg alloy during extrusion are described in this paper.The evolution of microstructure of alloy during hot extrusion was introduced,and the nucleation mechanisms of dynamic recrystallization and mechanism of texture weakening were summarized.The effects rules of extrusion parameters(extrusion temperature,extrusion rate and extrusion ratio)on the properties of extruded alloys were discussed.The research progress of Mg-Al,Mg-Zn,Mg-Sn and Mg-RE high-strength extruded Mg alloys in recent years was reviewed in detail from the aspects of alloy composition design and alloy system,and the strengthening mechanism of high-strength Mg alloys was analyzed.The new alloy design and process route were proposed for extruded Mg alloy considering the gap between extruded Mg alloy and extruded Al alloy,and prospects regarding the development of Mg extrusion alloys with high performance were discussed.