在本研究中，我們以火花電漿燒結(Spark Plasma Sintering)製備添加不同粒徑大小的ZnO (2.4 μm and 160 nm) 和添加不同重量百分比(1 wt% and 5 wt%) 的AZ91鎂合金，並研究其微觀結構及機械性質。微觀結構的觀察指出，添加微米及奈米等級的ZnO顆粒會明顯地降低AZ91鎂基複合材料的晶粒尺寸。在添加5 wt%微米等級的ZnO顆粒後，AZ91鎂合金的平均晶粒尺寸會從46.14 nm降至38.16 nm 。此外，添加5 wt.%奈米等級的ZnO顆粒AZ91鎂合金的平均晶粒尺寸會從46.14 nm 降至 33.61 nm。在火花電漿燒結製程中，AZ91鎂合金的孔隙率為13.66 %， 在添加5wt.% 微米等級的ZnO以及5wt.% 奈米等級的ZnO，孔隙率分別減少至9.42 %和8.72 %。添加微米等級及奈米等級的ZnO顆粒後，AZ91鎂合金的硬度值分別從138 HV提升至151 HV和153 HV。微米及奈米等級的ZnO顆粒添加，可提升AZ91鎂合金的極限抗壓強度(UTS)分別從256 MPa提升至328及351 MPa，破斷應變則由3.6 % 分別提升至3.9 %及4.2 %。因此，本次實驗結果顯示，添加 5 wt.%奈米等級ZnO顆粒的AZ91鎂基複材之機械性質優於添加5 wt.%微米等級ZnO顆粒的複材。

In this work, AZ91 magnesium alloys reinforced in different size (2.4 μm and 160 nm) of ZnO particles with different weight percentage (1 and 5) were fabricated by spark plasma sintering (SPS) and their microstructure and mechanical properties were studied. From the microstructure observation, it was found that adding micro (m-) and nano (n-) ZnO particles into the AZ91 Mg matrix significantly decreased the grain size of the AZ91 Mg composites. After addition of 5 wt% m-ZnO, the average grain size of the AZ91 Mg alloy decreased from 46.14 to 38.16 nm. Furthermore, after the addition of 5 wt% n-ZnO, the average grain size of the AZ91 Mg alloy decreased from 46.14 to 33.61nm. In SPS process, the porosity of AZ91 Mg alloy is 13.66%, after addition of 5 wt% m-ZnO and 5 wt% n-ZnO particles, the porosity of AZ91 Mg alloy is reduced from 13.66% to 9.42% and 8.72% respectively. The presence of micro and nano-ZnO particles was used to enhance the hardness value of AZ91 Mg alloy from 138 HV to 151 HV and 153 HV. The reinforcement of micro and nano-ZnO particles increased the ultimate tensile strength (UTS) of AZ91 Mg from 256 MPa to 328 and 351 MPa, the strain increased from 3.6% to 3.9% and 4.2%. Thus, the results indicate that the addition of 5 wt% n-ZnO in AZ91 Mg alloy has superior mechanical properties compared to that of 5 wt% m-ZnO particles in AZ91 Mg alloy.

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