本研究以AZ91合金作為基材，添加微量石墨片和奈米碳管以及石墨烯。透過攪拌鑄造法製成鎂基複合材料，分別製成合金材料，並進行成分分析、顯微結構的觀察、機械性質測試、熱傳導係數分析，探討分別添加石墨片和奈米碳管以及石墨烯對 AZ91合金之相變化以及機械性質、熱傳導係數的影響。
研究結果顯示，分別添加石墨片和奈米碳管以及石墨烯之鎂基複合材料，其相組成為?-Mg、Al8Mn5、Mg17Al12，並無新相出現。從晶粒尺寸可發現分別添加石墨片和奈米碳管以及石墨烯可造成細晶強化之效果，從添加量0.2 wt.%添加至0.6 wt.%，AZ91原材之151 ??下降至石墨烯98 ??。硬度值相比於AZ91，從原本72 HV提升至84 HV，以及石墨烯之抗拉強度明顯提升，從AZ91之123.5 MPa上升至178.1 MPa。降伏強度則從AZ91之76.9 MPa提升至134.4 MPa，延伸率從AZ91之4.7 %上升至7.4 %。
熱傳導係數由AZ91原本的46.50 W/m．k上升至50.37W/m．k，並無大幅提升，原因為攪拌鑄造無法將強化相均勻分散，造成部分團聚的現象以及孔洞的出現，這對於強度以及晶粒尺寸，皆有明顯的影響。

In this study, AZ91 alloy was used as the base material, and trace amounts of graphite flakes and nanocarbon tubes as well as graphene were added. The magnesium-based composites were produced by stir casting method, and the alloys were separately produced. Composition analysis, microstructure observation, mechanical property test, and thermal conductivity analysis were carried out to investigate the effects of the addition of graphite flakes, nanocarbon tubes, and graphene on the changes in AZ91 alloy as well as on the mechanical properties and thermal conductivity.
The results show that the phase composition of the magnesium-based composites with the addition of graphite flakes, nanocarbon tubes, and graphene is ?-Mg, Al8Mn5, and Mg17Al12, and no new phases appear. From the grain size, it can be found that the addition of graphite flakes and nanocarbon tubes as well as graphene can cause the effect of fine-crystalline enhancement, respectively, but with the increase in the amount of addition the grain size increases, and the best fine-crystalline enhancement in the grain size of the magnesium-based composites is the graphene from 98 ?? to 128 ??. The hardness value increased from 72 HV to 84 HV compared to AZ91, and the tensile strength of graphene increased significantly from 152.2 MPa to 178.1 MPa, the yield strength increased from 125.8 MPa to 134.4 MPa, and elongation increased from 7.0 % to 7.4 %.
The thermal conductivity increased from 46.50 W/m.k of AZ91 to 50.37 W/m.k, which is not a significant increase. The reason is that the stir casting cannot disperse the reinforced phase uniformly, resulting in the phenomenon of partial agglomeration and the appearance of holes, which has a significant effect on the strength and grain size.

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