Fabrication, microstructure and compressive behavior of ZC63 Mg-microballoon foam composites
Fabrication, microstructure and compressive behavior of ZC63 Mg-microballoon foam composites
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DOI：
10.1016/j.compscitech.2006.10.023
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发表时间：
2007-07-01
影响因子：
9.1
通讯作者：
Rohatgi, P.
中科院分区：
文献类型：
--
作者：
Daoud, A.;Abou El-Khair, M. T.;Rohatgi, P.
采用熔体搅拌法制备了ZC 63镁合金-粉煤灰微珠泡沫复合材料。研究了熔体温度、搅拌器类型和尺寸、浇注温度和模具类型等工艺参数对飞灰微球在镁合金中分布的影响。复合材料的密度测量表明，粉煤灰微球的加入显着降低了复合材料的密度。随着微球体积分数的增加，复合材料的密度降低。复合材料在铸态条件下表现出较小的枝晶臂间距/细胞尺寸相比，未增强的ZC 63镁合金。复合材料的平均枝晶臂间距/晶胞尺寸约为10 μ m，而未增强的镁合金为100 μ m。复合材料的显微组织表明，微球在镁合金基体中均匀分布，没有飞灰团和残余孔隙。此外，还观察到有一些填充有镁基合金的飞灰微球。SEM观察表明，飞灰微球、共晶相和其他金属间化合物在镁合金胞间偏析。复合材料界面的检查表明，共晶和其他金属间化合物相能够在飞灰微球上不均匀地成核。复合材料的SEM、XRDA和EDXA显示了粉煤灰/基体界面反应产物的明显证据。通过XRDA和EDXA分析，结合成分、结构和热力学分析，确定粉煤灰与ZC 63镁合金之间的主要界面相为MgO。对泡沫复合材料的压缩性能进行了表征。在本工作中生产的泡沫复合材料表现出典型的行为的弹塑性泡沫材料在压缩。它们有一个初始的线性弹性区域，然后是一个相对平坦的应力水平下的长变形区域。与固体ZC 63基体合金或含有25体积%微球的复合材料相比，含有高达20体积%微球的复合材料显着显示出更高的能量吸收。(C)2006爱思唯尔有限公司版权所有。
ZC63 Mg alloy-fly ash microballoon foam composites were fabricated by melt stir technique with the use of fluxes. The influence of various processing parameters such as melt temperature, type and dimensions of the stirrer, pouring temperature and mould type on distribution of the fly ash microballoons in the Mg matrix alloys was presented. Density measurements of the composites revealed that the addition of fly ash microballoons significantly reduced the density of the composites. As the volume fraction of microballoons increased, the density of the composites decreased. Composites in the as-cast condition exhibited smaller dendrite arm spacing/cell size compared to unreinforced ZC63 Mg alloy. The average dendrite arm spacing/cell size of the composites was about 10 Pm compared to 100 mu m of the unreinforced magnesium alloy. The microstructure of the composites demonstrated even distribution of the microballoon in the Mg alloy matrix and there was no sign of fly ash cluster or residual porosity. Also, it was observed that there were some fly ash microballoons filled with Mg matrix alloy. SEM micrographs showed those fly ash microballoons, eutectic phase and other intermetallic compounds segregated at the magnesium cell boundaries. Examination of the composite interface indicated that the eutectic and other intermetallic compounds phases were able to heterogeneously nucleate on the fly ash microballoons. SEM, XRDA and EDXA of the composites showed clear evidence of reaction product at fly ash/matrix interface. On the basis of XRDA and EDXA, composition, structure and thermodynamic analysis, the main interfacial phase between the fly ash and ZC63 Mg alloy was identified as MgO. The compressive properties of the foam composites were characterized. The foam composites produced in the present work demonstrated typical behavior of an elastic-plastic foam material in compression. They had an initial linear elastic region, followed by a long region of deformation at a relatively flat stress level. The composites containing microballoons up to 20 vol% significantly revealed higher energy absorption in comparison to the solid ZC63 matrix alloy or the composite containing 25 vol% microballoons. (C) 2006 Elsevier Ltd. All rights reserved.