壓鑄鋁合金及球墨鑄鐵（Ductile cast iron）廣泛地應用在各領域，而在管線或引擎等應用場合，磨耗所造成的重量損失導致工件破壞是必須被考慮的。本實驗材料選擇ADC1C組成的壓鑄Al-14Si合金及FCD450肥粒體基球墨鑄鐵（Fe-2.9C-2.5Si）為實驗材料，此兩者均具有第二相顆粒散佈在基地中。本論文針對這兩種具不同第二相顆粒之材料進行顆粒沖蝕磨耗行為研究，並探討摩擦攪拌製程（Friction stir process, FSP）對顆粒沖蝕阻抗的改質效果。
本研究利用摩擦攪拌製程（Friction stir process, FSP）進行表面改質，鋁合金採用具有凸鞘的攪拌工具，鑄鐵則選用無凸鞘的攪拌工具。之後探討材料經過摩擦攪拌後基地相變態的現象，以及軟硬質第二相顆粒的演變。在這樣的基礎上，本研究進一步探討不同材料的不同組織在顆粒沖蝕磨耗行為所扮演的角色，其中沖蝕顆粒均選用SiO2，壓鑄Al-14Si合金固定沖蝕顆粒飛行速率為66 m/s，沖蝕角度為15°及90°；球墨鑄鐵則是16 cm/s的沖蝕顆粒飛行速率，並改變沖蝕角度從20°漸次增加沖蝕角度至90°。
實驗結果發現，鑄態的壓鑄Al-14Si合金除了樹枝狀的α-Al以外，更含有大量第二相，由面積率的的多寡來看，分別為不規則或針狀的共晶矽、長條狀的β-Al3 (Fe, Mn) Si2以及最少量的塊狀初晶矽。當壓鑄Al-14Si合金經過摩擦攪拌後，樹枝狀區間消失，初晶矽呈較小的塊狀，共晶矽及β相亦被細化，縱橫比下降。在顆粒沖蝕磨耗行為方面，壓鑄Al-14Si合金及改質後的材料在高角度的磨耗阻抗均高於在低角度的。顯示了這兩組材料之磨耗行為受延性機制主導，主要為α-Al基地的塑性變形，以及切削的作用。而不論是斜向或正向沖蝕，攪拌後的試片均具有較佳的磨耗阻抗，這可歸納為第二相顆粒的細化、縱橫比下降而減低顆粒脆性破斷的機會，並且第二相顆粒散佈於基地中更能有效地阻止基地塑性變形。
具軟質石墨顆粒的肥粒體基球墨鑄鐵經過攪拌後，由硬度分布及組織差異可發現表層區域發生相變化。最上層為熱機影響區，此區與鄰近的熱影響區基地組織相似，主要以針棒狀的麻田散體相及塊狀或片狀的沃斯田體組成。最大的差異為石墨形貌，前者可見因攪拌時應力作用而變形的石墨，後者則未受力，維持原始的球狀。距表面更遠的熱影響區，則只有部分基地發生相變態，且大致傾向於石墨附近發生。這些區域由透鏡狀的麻田散體及塊狀的沃斯田體組成，其他未變態的區域則維持肥粒體基地。變態的區域中，多出現麻田散體平板且具有高碳麻田散體的特徵。至於沖蝕磨耗行為，從磨耗曲線可以觀察到，肥粒體基試片的低角度磨耗阻抗劣於高角度，這顯示延性的磨耗機制主導了肥粒體基試片的重量損失。但攪拌後試片的磨耗率則顯現了雙峰值的現象，分別在約30°及60°時出現；低角度峰值的出現意味著此時的延性機構較為顯著，基地及石墨的塑性變形為造成重量損失的主因；60°峰值的出現應是脆性的麻田散體相與具較佳延性的殘留沃斯田體相調和之故。此外，在低角度沖蝕時，攪拌試片之磨耗阻抗較肥粒體基試片為佳，在高角度沖蝕時則顯示了相反的結果，主要因素為硬脆的麻田散體相生成導致基地較不易塑性變形，但當在高角度受的衝擊較大時，反而易脆性破斷所致。

The current research aimed to explore the particle erosion of a die cast Al-14Si alloy ADC1C and ferritic ductile cast iron FCD450, and how the particle erosion behavior can be affected by modification of the microstructure via friction stir processing (FSP). In this study, perform FSP on die cast Al alloys by a conventional stirring tool with a pin, but ductile cast iron applied with no-pin tool. After specimens being stirred, evolution of matrix and second phase is investigated. Therefore, we discuss the different microstructure of different materials how to affect the erosion wear behaviors. The results indicate that friction stirring of the Al alloy can annihilate the dendritic structure of primary α-Al, break the eutectic Si and β-Al3(Fe,Mn)Si2 particles lengthwise, cause the eutectic Si particles to become more rounded, and blend the second phase particles rather uniformly in the α-Al matrix. According to the SiO2 particle erosion test, this microstructure modification improves the erosion resistance by not only second phase dispersion but also suppressing the opportunity of brittle cracking of the second phase particles. As for FCD450, the modified surface transformed to a thermal mechanical affected zone and a heat affected zone. The former includes elongated graphite, lenticular martensite and chunck-like or film-like retained austenite. The heat affected zone close to the thermal mechanical affected zone maintains nodular graphite and the similar matrix as the above. However, the farther reveals the hard-eye structure. The results of erosion test on ductile iron indicate that the modified surface reveals better erosion resistance at oblique impact; owing to the hard, brittle martensite and elongated graphite. However surface modification does not improve the erosion resistance at high angle impact. The friction stirred cast iron depicts maximum erosion rate at 30° and 60° impact, where the former is governed by ductile erosion and the latter by the brittle effect.

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