本研究以Fe-Cr-Mo-C-B-Y-Co七元合金成分作為基礎，透過真空感應高週波熔煉並澆鑄成鐵基金屬玻璃合金鑄錠，再以氣噴粉體法(Gas atomization)製備出鐵基金屬玻璃球型粉體，每一爐次粉體均經搖篩機篩分後，再以X光繞射分析確認粉體非晶性。研究結果顯示粉體粒徑53μm以下皆為非晶態，粉體粒徑>53 μm則有微量碳化鉻(Cr23C6)結晶相產生；同時，隨著粉體粒徑上升，碳化鉻結晶峰之峰值強度也隨之提高；粉體外觀呈現球形且其截面為實心構造，適合積層製造使用。積層製造為目前被認為最有能力實行異型水路製作的技術，未來會將鐵基金屬玻璃粉體應用於積層製造MIM異型水路模具。然而，鐵基金屬玻璃雖擁有高強度、高硬度及優異的耐腐蝕性，但由於其韌性仍嫌不足，必須加以提升，方可應用在MIM異型水路模具上。所以本研究同時致力於鐵基金屬玻璃韌性提升之研究，藉由微量添加不同比例之銅元素進行改質，藉以提升此基材之破裂韌性。以真空傾倒式鑄造製備出4 mm之鐵基金屬玻璃棒材時，由於內添加之銅元素於鐵基合金中的鐵元素在高溫熔融狀態下不互溶，於急速冷卻下會被析出至鐵基合金的基地組織中，同時於基地組織中也可觀察到另一析出相，碳化釔(Y2C)析出相。研究結果顯示，添加銅元素之鐵基金屬玻璃之破裂韌性比其基材有顯著之提升，其破裂韌性數值由4.78 ± 0.9 MPa∙√m提升至8.18± 1 MPa∙√m。;In this study, the composition of Fe-Cr-Mo-C-B-Y-Co 7 components was selected as the base alloy to prepare the alloy ingot by vacuum induction melting. Then, the alloy ingots were re-melted and fabricated into metallic glass powder by inert gas atomization in Industrial Technology Research Institute (ITRI, Hsinchu). The atomized powders were sieved by a sieve shaker to classify the powder size and obtain the size distribution of powder. Different sizes’ powders were characterized by X-ray diffraction to identify its amorphous state, respectively. Meanwhile, the surface morphology and cross-sectional image of atomized powders were examined by scanning electron microscope. As a result, the atomized powders with particle size less than 53μm exhibit a fully amorphous state. On the contrary, the powder with particle size above 53μm was found to contain a little chromium carbide (Cr23C6) phase co-existing with the amorphous matrix. The intensity of Cr23C6 crystalline peak increases with increasing the powder size. In addition, the appearance and cross-sectional image of the atomized powders were revealed to have a spherical shape and solid structure, respectively by the observation of scanning electron microscope. These atomized Fe-based MG powders are recognized suitable for additive manufacturing application on metal injection mold (MIM). However, though the Fe-based metallic glass alloy has excellent glass forming ability, high strength, high hardness, and superior corrosion resistance, its fracture toughness may still not strong enough to meet the requirement of MIM mold and need to be further improved. Therefore, the Fe-based metallic glass alloy was modified by adding small amount of Cu to enhance its fracture toughness. The Fe-based bulk metallic glass (BMG) rods with 4 mm in diameter were successfully fabricated by vacuum tilt casting. During rapid cooling, Cu acts as a heterogeneous nucleation site to induce -phase iron precipitation 1n the Fe-based amorphous matrix. The results show that Fe-based BMG added with 3 at% Cu presents higher fracture toughness value (8.18± 1 MPa∙√m) than the based one (4.78 ± 0.9 MPa∙√m ).
