4384鋁合金含有近共晶組成的Si含量，而大量在α-Al基地中晶出的硬質相使4384鋁合金有較低的熱膨脹係數、良好的耐磨耗性質及高溫強度，於傳動系統的引擎中被廣泛地使用。但大量的硬質相存在於α-Al基地中也造成材料的延性表現不佳，加工成形性受限。
本研究選取旋鍛棒材作為原始材料並以未經旋鍛之熱擠型棒材做為對比材，接著利用480℃固溶化處理改質，提升4384鋁合金之延性，並以工業界常用之415℃退火處理作為比對的熱處理法。利用OM、SEM、XRD、HRF硬度測試、奈米壓痕測試與拉伸測試來探討旋鍛及固溶化處理對4384鋁合金其微觀組織及拉伸性質之影響。
實驗結果顯示，4384鋁合金中除了有大量的共晶Si，也有δ相與Q相存在於α-Al基地中。共晶Si經旋鍛後被打散而更細密。退火處理使共晶Si邊緣圓鈍化，而固溶化處理除了圓鈍化效應之外還將共晶Si固溶回α-Al基地中使共晶Si尺寸、面積分率與顆粒密度下降。
退火處理及固溶化處理皆能改善延性。退火處理消除加工硬化效應而軟化α-Al基地，而固溶化處理除了消除加工硬化效應之外，過飽和固溶與後續自然時效析出也對α-Al基地之變形阻抗有所貢獻，較能阻止裂紋傳播。以上結果顯示，經旋鍛與固溶化處理之4384鋁合金對於裂紋成長之阻抗較高，故均勻變形量表現最為優異，且根據計算加工硬化率的結果，加工硬化率最高者為經固溶化處理之旋鍛4384鋁合金。選擇均勻變形量與加工硬化率皆有最佳表現的固溶化處理之旋鍛4384鋁合金作為加工成形使用最為合適。

4384 aluminum alloy with near-eutectic Si content is widely used in engine. Many hard phases in α-Al matrix cause low ductility of 4384 aluminum. In this study, rotary swaging and solid solution were chosen to improve formability by improving ductility and work hardening rate. We chose the rotary swaged 4384 aluminum alloy bar to compare with extrusion bar (non-rotary swaged). Solid solution treatment was used to improve formability of these two bars and compare with annealing treatment which was widely used in industry. OM, SEM, XRD, Nano indenter and tensile test were utilized to investigate microstructure and tensile properties.
From the experimental results, there are not only many eutectic Si but also δ phases and Q phases existing in 4384 aluminum alloy. After rotary swaging, eutectic Si was smashed. Annealing treatment made the edge of eutectic Si be rounded. Solid solution treatment made not only eutectic Si be rounded but also reduce the size and area fraction decrease.
Annealing treatment can remove work hardening effect. Expect removing work hardening effect, solid solution treatment makes α-Al matrix supersaturated state and precipitation can inhibit cracks growth.
Results shows that 4384 aluminum alloy during rotary swaging and solid solution treatment has the best uniform elongation and work hardening rate. Rotary swaged 4384 aluminum alloy during solid solution treatment is the most suitable choice for forming.

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