本研究以AZ91合金作為基材，添加微量元素銻 ( Sb ) 和奈米粒徑之碳化矽 ( SiC ) 顆粒。透過攪拌鑄造法製成鎂基複合材料，分別 製成單一添加與混合添加之合金材料，並進行成分分析、顯微結構的觀察、機械性質測試，探討同時添加Sb和SiC顆粒對 AZ91合金之變化以及經熱處理過後機械性質的影響。
研究結果顯示，同時添加Sb及SiC之鎂基複合材料，其相組成為?-Mg、Mg3Sb2、Al8Mn5、Mg17Al12及SiC。從晶粒尺寸可發現同時添加Sb和SiC可造成細晶強化之效果，鎂基複合材料之晶粒尺寸因異質成核從177.8 ??下降至120.5 ??，經固溶及時效熱處理後晶粒尺寸會些微提升至140.8 ??。硬度值相比於AZ91，從原本62.71 HV提升至73.84，經固溶及時效熱處理後提升至84.33 HV。但由於添加SiC陶瓷顆粒會傾向出現在晶界上並有團聚之狀況發生，AZ91複合材料之抗拉強度無法像添加Sb明顯提升，從126.9 MPa上升至147.8 MPa。降伏強度則從39.9 MPa提升至47.9 MPa，延伸率從1.3 %上升至4.4 %。經固溶及時效熱處理後抗拉強度和降伏強度分別為149.2 MPa及60.8 MPa，延伸率為4.5 %。
使用攪拌鑄造無法將SiC顆粒均勻分散，造成有部分團聚的現象。
由於使用重力鑄造，在冷卻過程中會有許多孔洞，對於拉伸試驗有明顯的影響。後續進行固溶及時效熱處理晶粒尺寸雖些微提升，但Mg17Al12連續相重新析出較小並分布於基材中造成散佈強化，材料機械強度皆有所提升。

In this study, AZ91 magnesium-based metal use as the matrix, and antimony (Sb) and silicon carbide (SiC) nanoparticle have been synthesized to prepare magnesium-based composite by stir casting method, then conduct the analysis of composition, microstructure observation and mechanical properties test, in order to explore the influence of adding Sb and SiC simultaneously into AZ91 magnesium-based metal, and the mechanically influence after doing heat treatment.
The results show that the Sb and SiC added magnesium-based metal was consist of ?-Mg, Mg3Sb2, Al8Mn5, Mg17Al12 and SiC, and the grain size showed that the addition of Sb and SiC could cause fine grain strengthening. The grain size of the magnesium-based composite material decreased from 177.8 ?? to 120.5 ??. After doing solid solution and aging heat treatment, the grain size slightly increased to 140.8 ??. To compare with AZ91, the hardness increased from 62.71 HV to 73.71 HV, and reach to 84.33 HV after doing aging heat treatment. Since that ceramic particles tend to agglomerate on the grain boundary, and AZ91 composite material has pores during casting, the tensile strength increase from 127.9 MPa to 130.3 MPa and the yield strength increase from 39.9 MPa to 47.9 MPa. The elongation decreased from 3.9 % to 3.6 %. After doing solid solution and aging heat treatment, the tensile strength and yield strength were 165.2 MPa and 60.8 MPa respectively, and the elongation was 3.7 %.
The SiC particles were not evenly dispersed by stir casting, resulting in partial agglomeration. Due to the gravity casting, there were many holes during the cooling process, which has an obvious effect on the tensile test. Even though the grain size slightly increased after doing solid solution and aging heat treatment, Mg17Al12 continuously becomes smaller and distribute in the base material causing dispersion strengthening that improving the mechanical strength.

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