铸造冷却方式对Mg-4.4Zn-0.3Zr-0.4Y挤压态合金组织及性能的影响  

Effect of Cooling Method on Microstructures and Mechanical Properties of Extruded Mg-4.4Zn-0.3Zr-0.4Y Alloy

作　　者：吕滨江[1,2] 彭建[2,3] 禇忠[1] 

机构地区：[1]青岛理工大学,山东青岛266520 [2]重庆大学,重庆400044 [3]机械传动国家重点实验室,重庆400044

出　　处：《稀有金属材料与工程》2017年第1期189-194,共6页Rare Metal Materials and Engineering

基　　金：国家"十二五"科技支撑计划(2011BAE22B03-3);科技部国际合作项目(2011DFA5090)

摘　　要：采用2种不同铸造冷却方式制备成分相同、组织特征不同的Mg-4.4Zn-0.3Zr-0.4Y镁合金,研究不同铸造组织特征对挤压变形态合金组织和力学性能的影响。结果表明:与空冷铸造合金相比,水冷增大了熔体冷却速度,使合金铸态组织得到细化,抑制了W-相(Mg_3Y_2Zn_3相)的形核,并促进了I-相(Mg_3YZn_6相)的生成,获得了更大体积分数的准晶相(I-相)。经过挤压变形后,水冷铸造合金中的再结晶晶粒细小均匀,I-相颗粒经过挤压破碎后弥散分布在基体上,{0002}基面织构得到弱化,而■织构强度增强,从而使Mg-4.4Zn-0.3Zr-0.4Y挤压态合金的强度和塑性都得到了大幅提高。水冷铸造合金经过挤压变形后,屈服强度和抗拉强度分别达到297.0和327.3 MPa,与空冷铸造挤压态合金相比分别提高了46.4和21.4 MPa。水冷铸造挤压态合金的延伸率达到14.8%,与空冷铸造挤压态合金相比增大了4.7%。Mg-4.4Zn-0.3Zr-0.4Y（wt%） alloy ingots were prepared by two casting processes with different cooling methods： air cooling cast（AC cast） and water cooling cast（WC cast）. Then, the two types of Mg-4.4Zn-0.3Zr-0.4Y alloy ingots were extruded under the same condition, and the effect of different cooling methods on microstructure and mechanical properties of the extruded alloy was studied. The results show that the cooling method of melt during cast processing has a great effect on microstructure and mechanical properties of the extruded alloy. Compared with AC cast alloy, the lamellar eutectic structure and dendrite cell size of WC cast alloy are significantly refined,while the formation of W-phase（Mg_3Y_2Zn_3） is suppressed and the volume fraction of I-phase（Mg_3YZn_6） increases in WC cast alloy. After extrusion deformation, the WC cast Mg-4.4Zn-0.3Zr-0.4Y alloy has finer dynamically recrystallized grains, finer and more uniformly fragmented I-phase particles distributed in the matrix and grain boundaries, weakened {0002} basal texture intensity and increased texture intensity compared with those of the extruded AC cast alloy. The yield strength and tensile strength of the extruded WC cast Mg-4.4Zn-0.3Zr-0.4Y alloy reach 297.0 and 327.3 MPa, which are increased by 46.4 and 21.4 MPa, respectively compared with those of the extruded AC cast alloy. The extruded WC cast Mg-4.4Zn-0.3Zr-0.4Y alloy shows an elongation of 14.8%, which is 4.7% improvement compared with that of the extruded AC cast alloy.

关 键 词：冷却方式 镁合金 准晶相 组织结构 力学性能 

分 类 号：TG146.22[一般工业技术—材料科学与工程]