Cu对高压凝固Mg-9Al-1Zn合金显微组织及力学性能的影响  

Effect of Cu Addition on Microstructure and Mechanical Properties of High Pressure Solidified Mg-9Al-1Zn Alloy

作　　者：徐畅 黄铎 林小娉 郭士琦[2] 何永鹏 XU Chang;HUANG Duo;LIN Xiao-ping;GUO Shi-qi;HE Yong-peng(School of materials science and engineering, Northeastern University, Shenyang 110819, Liaoning, China;School of resources and materials, Northeastern University at Qinhuangdao, Qinhuangdao 066004, Hebei, China;Key Laboratory of Advanced Metal Materials and Forming Technology, Qinhuangdao University, Qinhuangdao 066004, Hebei, China)

机构地区：[1]东北大学材料科学与工程学院,辽宁沈阳110819 [2]东北大学秦皇岛分校资源与材料学院,河北秦皇岛066004 [3]东北大学秦皇岛分校秦皇岛市先进金属材料及成型技术重点实验室,河北秦皇岛066004

出　　处：《铸造》2019年第8期860-866,共7页Foundry

基　　金：国家自然科学基金(51675092;51775099);河北省自然科学基金(E2018501033)

摘　　要：研究了常压及2 GPa级高压作用下,Mg-9Al-1Zn-0.5Cu合金微观组织和力学性能。结果表明:常压下,Mg-9Al-1Zn-0.5Cu合金铸态组织由等轴晶α-Mg、连成网状分布在枝晶间"骨骼状"的β-Mg17Al12共晶相和枝晶间富铝而形成的白色层片状中间相β-Mg17Al12以及极少量的Al6CuMg4相组成,平均晶粒尺寸为192μm。在2 GPa高压凝固后,微观组织由等轴晶α-Mg、呈颗粒状或长岛状断续分布在枝晶间的β-Mg17Al12共晶相以及少量的Al6CuMg4相组成,平均晶粒尺寸仅为23μm,Al在基体中的固溶量高达5.81%;该合金的室温压断最大抗力为475 MPa,断面膨胀率为31%,比常压下的铸造合金分别提高53%和38%。其凝固组织细化、颗粒状或岛状共晶相β-Mg17Al12的弥散强化以及Al在基体中的固溶强化是其强度提升的主要机制,而组织细化和晶间第二相形态的改变是其塑性提升的主要原因。The microstructure and mechanical properties of Mg-9Al-1Zn-0.5Cu alloy solidified under normaland 2GPa high pressures were studied.The results show that the as-cast microstructure of Mg-9Al-1Zn-0.5Cu alloy by metal mold casting consists of equiaxed crystalα-Mg,eutectic phaseβ-Mg17Al12 distributing between dendrites in skeleton shape,white lamellar mesophaseβ-Mg17Al12 formed by rich aluminum between dendrites and a very small amount of Al6CuMg4 phase,with an average grain size of 192μm;the solidificationmicrostructure under 2 GPa high pressure consists of equiaxed crystalα-Mgwith complete regularity,eutectic phaseβ-Mg17Al12 and a small amount of Al6CuMg4 distributing intermittently between dendrites in granular or long island shape,its average grain size is only 23μm,and the solid solubility of Al in the matrix is as high as 5.81%.The maximum fracture resistance and section expansion rate at room temperature are 475 MPa and 31%,which arerespectively 53% and 38%higher than that of the Mg-9Al-1Zn-0.5Cu alloy solidified under normal pressure.Fine solidification microstructure,dispersive strengthening of granular or island eutectic phaseβ-Mg17Al12 and solid solution strengthening of Al in the matrix are the main mechanisms for strength enhancement,while the main reasons for plasticity enhancement are grain refinement and change of second phase morphology.

关 键 词：高压凝固 Mg-9Al-1Zn-1Cu合金 凝固组织 共晶相 

分 类 号：TG146.2[一般工业技术—材料科学与工程]