Microstructure and Mechanical Properties of Alumina-Dispersed Magnesium Fabricated Using Mechanical Alloying Method
Microstructure and Mechanical Properties of Alumina-Dispersed Magnesium Fabricated Using Mechanical Alloying Method
复制标题
机械合金化法制备氧化铝弥散镁的显微组织和力学性能
DOI：
10.2320/matertrans.48.373
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发表时间：
2007
影响因子：
1.2
通讯作者：
T. Machida
中科院分区：
文献类型：
--
作者：
Shigehiro Kawamori;T. Machida
为了改善镁合金的力学性能，作为粉末冶金技术的应用，对α-Al_2O_3颗粒(PAL_2O_3)的弥散强化进行了试验研究。试验过程包括球磨、压实和热压。采用光学显微镜、扫描电子显微镜、X射线衍射仪和电子探针分析了镁复合材料热压圆盘的显微组织，并对其密度、表面硬度和弯曲变形应力进行了测试。所有的机械合金化(MA)粉末都只由镁和氧化铝组成。虽然MA粉末的粒度有所不同，但其平均值约为80μm，约为原始镁粉的一半。随着加工过程的进行，不仅镁粉变细，PAL_2O_3也变得更加细小，PAL_2O_3几乎均匀地分散在镁粉中。此外，细小的PAL_2O_3颗粒几乎均匀地分散在PAL_2O_3弥散强化的镁片中。在所有的光盘中，除了镁和氧化铝外，还发现了少量的氧化镁(MgO)。然而，仅在22.7%PAL_2O_3/mg光盘中，除了Mg、Al_2O_3和MgO外，还检测到一个属于Al-Mg金属间化合物(Al_(12)Mg_(17))的X射线衍射峰。认为Al-12-Mg-17是由Al_2O_3和Al_2O_3固相反应生成的，它出现在纯镁和Al_2O_3弥散在镁中的交界处。所有PAL_2O_3含量的盘片密度均高于理论密度；最高PAL_2O_3含量为22.7%的盘片密度约为实际铝合金的0.8倍。22.7%PAL_2O_3圆盘的最大硬度值为280HV。这一数值远高于纯镁锭和AZ91D。挠曲弯曲应力随PAL_2O_3含量的增加而降低。其原因被认为是因为圆盘变得更硬和更脆，更容易在圆盘中形成空洞；因此，在试件表面产生的裂纹更容易扩展。
In order to improve the mechanical properties of magnesium, dispersion strengthening with α-alumina particles (pAl 2 O 3 ) is experimentally investigated as an application of powder metallurgy. The trial process consists of milling, compacting and hot-pressing. The microstructure of hot-pressed discs of magnesium composites were investigated using optical microscopy, scanning electron microscopy, x-ray diffraction (XRD) and electron probe micro analysis, and the density, surface hardness, and bending stress for deflection were also examined. All of the mechanically alloyed (MA) prepared powders were composed of only magnesium (Mg) and alumina (Al 2 O 3 ). Although the particle size of the MA powders varied, the mean values were approximately 80 μm and were approximately the half size of the raw Mg powder. Not only Mg powder, but also pAl 2 O 3 became finer with processing, and the pAl 2 O 3 was almost uniformly dispersed in the Mg powder. In addition, the fine pAl 2 O 3 was almost uniformly dispersed within the Mg of the pAl 2 O 3 dispersion strengthened (ODS) magnesium discs. For all discs, a small quantity of magnesium oxide (MgO) was identified along with Mg and Al 2 O 3 . However, in only the 22.7 vol% pAl 2 O 3 /Mg disc, an XRD peak assigned to an Al-Mg intermetallic compound (Al 12 Mg 17 ) was detected, in addition to Mg, Al 2 O 3 and MgO. It is proposed that Al 12 Mg 17 was produced by the solid-state reaction of Mg and Al 2 O 3 , and appeared at the interface between the regions of only Mg and regions where pAl 2 O 3 is dispersed in Mg. The density of the discs was above the theoretical density for all pAl 2 O 3 content; the density for the highest pAl 2 O 3 content of 22.7 vol% was approximately 0.8 times greater than that of practical Al alloys. The 22.7 vol% pAl 2 O 3 disc had a maximum hardness value of 280 HV. This value is much higher than that of both pure Mg ingot and AZ91D. The bending stress for deflection decreased with an increase in the pAl 2 O 3 content. The reason for this is considered to be that the discs become harder and more brittle, and voids are more easily formed in the discs; therefore, cracks that are generated on the specimen surface propagate more easily.