鎂基複合材料 (Magnesium metal matrix composites, Mg MMCs) 具有比鎂合金相對優異的力學性能，經由在基材中加入如微型顆粒、短纖維和連續纖維等強化相，使基材和強化相在擁有良好的結合性的情況下，以提升機械性質。本研究探討添加不同強化相粒徑 (1 μm、10 μm、50 nm) 與重量百分含量 (0.5、1、2 wt.%) 之SiCp碳化矽顆粒所製備的AZ61/SiCp鎂合金複材擠製平板，針對碳化矽顆粒在機械性質所造成的影響，以及平板在擠製後的後續退火處理所造成的微觀結構演變，材料強度、延展性及成形性等機械性質的改變進行深入探討。最後，再以「田口方法」結合「模糊邏輯理論」方法，在顧及各項材料性質的多重品質特性指標 (Multiple performance characteristics index, MPCI) 條件下，提出最適化製程參數組合，並以實驗來驗證其結果，設計出具備各項重要指標性能的材料。

本研究結果顯示，隨著強化相顆粒的添加，擠板在各項機械性質皆能有效的提升，且強化相粒徑尺寸越小，對晶粒的細化效果越明顯，各項機械性質提升幅度也愈大。其中以1 wt.% SiCp/50 nm的組合具有相對優異的機械性質，其極限強度331 MPa、降伏強度136.4 MPa、伸長率43.1%、硬度62 HV、晶粒尺寸3.3 μm、I.E.值1.69 mm，相較於未添加SiCp的鎂基複材擠製板材分別提升 (細化) 了6.4%、3.4%、83.4%、2%及13.2%，但成形性則下降了9.1%。

在施以250℃/ 1 hr的退火處理後，添加1 μm與50 nm的組合在硬度及強度部分皆有所提升，而延展性則因析出的β相導致小幅下降; 添加10 μm強化相的擠板雖然在0.5 wt.%時各項性質皆有所提升，但隨著添加量的上升會使析出物產生過多，進而導致強度、延展性與成形性急遽的下降; 無添加強化相的AZ61擠板在經過退火處理後，各項性質的提升幅度皆勝過有添加強化相的組合，但添加1 μm與50 nm強化相的組合在強度上仍舊勝過無添加強化相的AZ61擠板，且同時保有相近的延展性與成形性，故添加強化相的組合在此製程上依舊有其優勢存在。

Magnesium metal matrix composites (Mg MMCs) possess relatively better mechanical properties than magnesium alloy, by adding reinforcements such as small particles, short fiber or continous fiber into the matrix. This study investigated the influence by addition of different size and proportion of SiCp for manufacturing AZ61/SiCp magnesium alloy composites extrusion plate, against the mechanical properties of silicon carbide particles caused by the impact, and carried depth discussion evolution of microstructure, changes of material strength, ductility, formability and other mechanical properties caused by subsequent annealing treatment after extrusion of plate. Fuzzy theory and Taguchi method were combined to analyzed the hot extrusion process and subsequent annealing of the magnesium alloy composite sheets. Under the condition of the MPCI, the optimal combination of process parameters was decided, the results were verified by experiments.

The results showed that the mechanical properties of plates can be improved with the addtion of reinforcement particles, and the more obvious effects of grain refinement due to the smaller reinforcement particles size, the enhancing rate of mechanical properties were greater. Among them, the combination of 1 wt.% SiCp/50 nm having a relatively excellent mechanical properties. The ultimate tensile strength, yielding strength, ductility, hardness and grain size of AZ61/1 wt.% SiCp/50 nm plate are 331 MPa, 136.4 MPa, 43.1%, 62 HV and 3.3 μm, respectively. Compared with the SiCp free Mg MMCs plate were enhance(or refinement) 6.4%, 3.4%, 83.4%, 2% and 13.2%, but formability decreased by 9.1%.

After subjected to annealing treatment at 250℃/ 1 hr, AZ61/SiCp/1 μm and AZ61/SiCp/50 nm MMCs plate exhibited improvement on hardness and strength in every particle percentage. However, due to the over amount of β precipitation, there was a slightly decline on ductility. Although AZ61/0.5 wt.% SiCp/10 μm MMCs annealed plate have improved various properties, but the amount of precipitate increased with the percentage of SiCp, which leads to drastic decrease of strength, ductility and formability. The mechanical properties of SiCp free AZ61 annealed MMCs plate are bigger that those of unannealed MMCs plate. But AZ61/SiCp/1 μm and AZ61/SiCp/50 nm MMCs having a higher strength compared to SiCp free AZ61 MMCs plate while maintaining ductility and formability similarly. Therefore, addtion of SiCp into AZ61 in the processing still possesses its advantages.

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