本研究以A356(Al-Si-Mg)、A206(Al-Cu-Mg)及AC2B(Al-Si-Cu)三種不同元素比例之鋁合金進行金屬模重力鑄造實驗，實驗目的為經由本實驗探索三種不同合金元素比例之鋁合金於鑄造實務上的氧化膜生成、孔洞缺陷程度及熱裂缺陷發生的條件，並透過調整鑄造參數如模具預熱溫度來改善問題。 實驗結果顯示模具預熱溫度的提高及超音波震盪輔助對於孔洞缺陷的產生有高度正相關，尤其是對於A356合金的提升更是明顯，而熱裂缺陷僅發生在A206合金，推測是其高含量的銅元素導致冷卻速度過快及凝固區間太大而產生，超音波震盪後的A356及AC2B其氧化膜形式有很大的不同，前者主要呈現集中在孔洞區域附近，而後者多為平均散佈在表面。 關鍵字:A356、A206、AC2B、重力鑄造、氧化膜、孔洞率、熱裂缺陷 ;This study conducted metal mold gravity casting experiments using three different aluminum alloy compositions: A356 (Al-Si-Mg), A206 (Al-Cu-Mg), and AC2B (Al-Si-Cu). The purpose of the experiment was to explore the formation of oxide films, the degree of porosity defects, and the conditions for hot cracking defects in these three different elemental ratio aluminum alloys during practical casting. Additionally, adjustments to casting parameters, such as mold preheating temperature, were made to address these issues. The experimental results showed a significant positive correlation between the increase in mold preheating temperature and the generation of porosity defects, especially in the case of A356 alloy. Hot cracking defects were observed only in the A206 alloy, possibly due to its high copper content, which led to rapid cooling and a wide solidification range. After ultrasonic vibration assistance, there were significant differences in the oxide film formation between A356 and AC2B alloys. In the former, oxide films were predominantly concentrated near the vicinity of pores, while in the latter, they were more evenly distributed on the surface. Keywords:A356、A206、AC2B、gravity casting、oxidation film、porisity rate、hot cracking defect
