共晶矽形貌對壓鑄鋁合金機械性質的影響

Effect of Morphological Changes of Eutectic Si Particles on the Mechanical Properties of Die Casting Al-Si Alloys

程泓耀(Hung-Yao Cheng) ； 吳英誌(Ying-Zhi Wu) ； 唐乃光(Nai-Guang Tang) ； 林渤詠(Bo-Yong Lin) ； 蔡孟修(Meng-Hsiu Tsai)

《鑄造工程學刊》 48卷1期 (2022/06) Pp. 9-14

摘要

本研究使用Silafont®-36鋁合金為實驗材料，以不改變成份條件下利用熱處理進行機械性質的改善，增加壓鑄鋁合金延展性及硬度，並探討固溶熱處理過程中共晶組織型態轉變對機械性質的影響。將Silafont®-36試片分別以三種不同固溶溫度450℃、500℃、540℃持溫30分鐘，之後進行150℃/2～8小時的時效處理。實驗結果發現固溶溫度在450℃～540℃範圍內，隨著溫度上升共晶矽的面積占比由32.64%降至20.61%；長短軸的比值由1.87降至1.65。顯示540℃固溶處理因較高的熱處理溫度讓多數的共晶矽溶入基底中，導致針狀的共晶矽被打斷而形成球化的形貌，使共晶矽的面積占比也相對的低。由於固溶處理對機械性質的影響不大，故後續將以時效處理進行硬度的驗證。在後續實驗中發現，相同的時效處理時間下，隨著固溶熱處理的溫度增加，維克式硬度也跟著增加。另一方面經由後續的時效處理後，發現共晶矽的長短軸無明顯變化。由此結果得知，共晶矽的長短軸比與固溶溫度有直接關係，與時效處理則較無關聯。

關鍵字

共晶矽 ； 固溶處理 ； 析出強化

並列摘要

In this study, Silafont®-36 was used as the experimental material, and the mechanical properties were improved by heat treatment without changing the composition. Increase the ductility and hardness of die-cast aluminum alloys, and explore the effect of eutectic structure transformation on mechanical properties during solution treatment. The test piece was treated with a solution treatment of 450 ℃, 500 ℃, 540 ℃/30 minutes and an aging treatment of 150 ℃/2～8 hours. The microstructure was observed with an optical microscope, and the solution temperature was found to be in the range of 450 ℃ to 540 ℃ The area ratio of eutectic silicon decreased from 32.64% to 20.61%;The ratio of the long and short axis decreased from 1.87 to 1.65. It shows that the 540 ℃ solution treatment caused most of the eutectic silicon to dissolve into the substrate due to the higher heat treatment temperature, causing the needle-like eutectic silicon to be broken to form a spheroidized appearance, making the area of the eutectic silicon also accounted for Relatively low. Since the solution treatment has little effect on the mechanical properties, the subsequent aging treatment will be used to verify the hardness. In subsequent experiments, it was found that the Vickers hardness increased from 84HV (450℃) to 137HV (540℃) under the same aging parameters but with different solution temperature treatments; the long and short axis of the eutectic silicon increased from 450 ℃ after solution. After aging, it changes to 1.83 at 450 ℃, 1.78 at 500 ℃, and 1.62 at 540 ℃. From the results, it is known that the aging treatment is not closely related to the long and short axis of the crystal grains.

並列關鍵字

Eutectic silicon ； Solution treatment ； Precipitation strengthening

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