挤压温度对Mg-3Zn-2.5Al-2.5Ca合金的微观组织和力学性能的影响  

Influence of Extrusion Temperature on Microstructure and Mechanical Properties of Mg-3Zn-2.5Al-2.5Ca Alloy

作　　者：陈鼎[1] 章凯 董鹏 陈振华[1] 

机构地区：[1]湖南大学材料科学与工程学院,湖南长沙410082

出　　处：《湖南大学学报（自然科学版）》2017年第12期14-19,149,共7页Journal of Hunan University:Natural Sciences

基　　金：美国波音公司合作项目(2015-SDB-127)

摘　　要：采用金相分析、扫描电镜分析、X射线衍射分析和拉伸测试等方法研究了不同挤压温度对Mg-3Zn-2.5Al-2.5Ca(ZAC333)合金的微观组织和力学性能的影响.结果表明,铸态组织的平均晶粒尺寸为185μm;随着挤压温度从623K降低到523K,由于发生了明显的动态再结晶,合金的平均晶粒尺寸从6.32μm减小到3.36μm.ZAC333铸态合金中沿着晶界分布的半连续Al_2Ca和连续Ca_2Mg_6Zn_3第2相在热挤压过程中也发生了明显的破碎而沿着挤压方向分布.与铸态合金的力学性能相比,挤压态ZAC333合金的力学性能有明显的提高.挤压态合金的抗拉和屈服强度分别从176 MPa和284 MPa提高到292 MPa和334 MPa,而延伸率从18%降低到9%.ZAC333合金性能的改善主要归功于热挤压过程中的动态再结晶细晶强化和第2相粒子破碎而产生细化弥散强化的共同作用.The effect of extrusion temperatures on the microstructures and mechanical properties of Mg-3Zn-2.5 A1-2.5Ca （ZAC333） alloy was investigated by metallograph, SEM, XRD and tensile tests. The results show that the average grain size of the as-cast alloy is 185 fire. Due to the dynamic recrystallization, the grain size of as-extruded alloys was reduced from 6.32 ffm to 3.36/~m with the extrusion temperature decreasing from 693 K to 523 K. The second phase of semi-continuous A12 Ca and continuous Ca2 Mg6 Zna was broken,which distributed along the grain boundary in the as-cast ZAC333 alloy. Compared with as- cast alloy, the mechanical properties of as-extruded ZAC333 alloy were improved. The tensile and yield strength of as-extruded alloy increased from 176 to 292 MPa, 264 to 334 MPa, respectively, while elongation decreased from 20% to 9%. The improvement of mechanical properties for ZAC333 alloy can be attributed to the couple effects of refined crystalline strengthening caused by dynamic recrystallization and dispersion strengthening for the refined second phases during hot extrusion.

关 键 词：ZAC333合金 挤压温度 动态再结晶 第二相 力学性能 

分 类 号：TG146.2[一般工业技术—材料科学与工程]