高能球磨对Mg-Zn-Zr合金微观组织与力学性能的影响

在氩气条件下以400r/min高能球磨镁合金粉末,并将球磨后的粉末经过冷压—热压烧结—热挤压成型。研究了不同球磨时间的粉末以及挤压态样品的微观组织和力学性能。结果表明:随着球磨时间的延长,粉末颗粒尺寸可以细化到8μm,晶粒尺寸有效细化到34nm,在整个球磨过程中粉末有一定程度的氧化,并伴随有MgO纳米颗粒产生。粉末经过热压烧结—热挤压成型后,材料内部有MgZn2相颗粒析出,且均匀分布于Mg基体中。随着粉末颗粒的细化,材料性能得到改善,当球磨至10h时,粉末挤压态样品的极限拉伸强度为365 MPa,压缩屈服强度高达325 MPa,极限压缩强度保持在466 MPa。球磨至25h,颗粒平均尺寸细化至8μm左右,使得颗粒表面能大幅度增大,颗粒表面的氧化膜增厚,在热压烧结过程中阻碍了颗粒之间的结合,进而使得材料的力学性能恶化。

Effect of High Energy Milling on the Microstructure and Mechanical Properties of Mg-Zn-Zr Alloy

High-energy milling of Mg alloy powder was conducted in argon atmosphere,and then the cold-pressing,hotpressing sintering and hot extrusion of the milled powder was performed.The microstructure and mechanical properties of the as-extruded samples at different ball milling conditions was studied.The results indicated that with the increasing milling time,the particle size was refined to 8 μm,and grain size was about 34 nm,oxidation of the powders still occurred during the process,nano-MgO particles were also produced.Precipitated phase (MgZn2) existed in the extruded alloys,and uniformly distributed in the Mg matrix.With refined particles,the material performance was significantly improved,when the milling time was up to 10 h,the ultimate tensile strength and compress yield strength of the as-extruded samples were 365 MPa and 325 MPa,respectively,the ultimate compression strength kept in 466 MPa.When the milling time was 25 h,the average particle size of the powders was about 8 μm,accompanied with increased surface energy and thickened oxide film of the particles,which resulted in the bad combination between particles and opposite effect on the mechanical properties of the material.