積層製造用高韌性鐵基金屬玻璃合金粉體之開發與製作;Development and fabrication of Fe-based metallic glass powder with high fracture toughness for additive manufacturing

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Title:	積層製造用高韌性鐵基金屬玻璃合金粉體之開發與製作;Development and fabrication of Fe-based metallic glass powder with high fracture toughness for additive manufacturing
Authors:	張喬冠;Chang, Chiao-Kuan
Contributors:	機械工程學系
Keywords:	鐵基;金屬玻璃;氣噴粉;積層製造;破裂韌性;Fe-based;Metallic glasses;Gas atomization;Additive manufacturing;Fracture toughness
Date:	2019-08-21
Issue Date:	2019-09-03 16:40:47 (UTC+8)
Publisher:	國立中央大學
Abstract:	本研究目標是製作出高韌性之鐵基金屬玻璃合金粉體，藉以應用於積層製造上，積層製造目前被認為是最有能力能應用至MIM異型水路製作技術上，而在未來會以此技術並結合鐵基金屬玻璃粉體開發出MIM異型水路模具。以Fe-Cr-Mo-C-B-Co-Y之合金組成作為實驗基礎，此成分具有優異的玻璃形成能力，且高硬度、高強度以及良好的耐腐蝕性質且使用工業級原料其製備成本也相對的低，但是，因其破裂韌性較低，本研究以改善其材料之破裂韌性為研究的首要目標藉以實現商業化的目的。根據金屬玻璃形成能力之三大準則以及微量添加法，挑選出金屬:鋁，藉由添加微量元素，配置出不同系列合金，以改善鐵基金屬之破裂韌性。使用真空傾倒式鑄造製備出4mm之鐵基金屬玻璃之棒材，再快速冷卻時，基地中會析出BCC結構之α-Fe樹枝狀的組織使成為非金質合金內之第二相。研究結果顯示(Fe43Co7Mo14Cr15C10B7.5Al3.5)，由於第二相軟相結構的產生，使得整體的鐵基金屬玻璃之韌性能有所改善。其破裂韌性數值由4.02 ± 0.2 MPa∙√m提升至12.29 ± 0.9 MPa∙√m。測試改質後的鐵基金屬玻璃複材與SS316、SS420、SKDII以及原基材鐵基金屬玻璃磨耗率，根據結果顯示，改質後的鐵基金屬玻璃複材之磨耗率(2.543 x 10-6 mm3/N·m)與原基材(2.064 x 10-6 mm3/N·m)兩者並無太大差異，和SS316 (2.078 x10-6 mm3/N·m)與SS420 (7.4 x 10-6 mm3/N·m)相比明顯低上許多，且和SKDII 之工具鋼相比(1.67 x 10-6 mm3/N·m)，也無太大的差異，顯示其鐵基金屬玻璃優良的耐磨耗性質。將此改質後的鐵基金屬玻璃複材以真空感應高週波融煉並澆鑄成鐵基金屬玻璃合金鑄錠，再以氣噴粉體法(Gas atomization)製備出金屬玻璃粉體，將每一爐次粉體經搖篩機篩分，再以X光繞射確認其各區間粒徑粉體之非晶性與析出相之關係，根據結果顯示，當粒徑在90µm以下，皆只保留非晶特徵峰以及α-Fe組織，隨著粒徑越小其α-Fe的結晶峰強度也隨之降低；而粒徑>90µm除了α-Fe之BCC結構外，還有碳化物的結構，之後運用掃描式電子顯微鏡觀測其粉體外觀，由結果顯示，粉體形貌為球型且截面皆為實心構造，故此粉體適合應用於積層製造上。關鍵字 : 鐵基金屬玻璃、破裂韌性、磨耗測試、氣噴粉體法、積層製造;In order to increase the cooling rate and molding life of the mold for metal injection molding (MIM), the stronger Fe based amorphous alloy powder accompanied with the laser additive manufacturing(LAM) technique were proposed to produce the MIM mold with conformal cooling channels. In this study, a modified Fe-based amorphous alloy composition with better fracture toughness was developed and fabricated into spherical powder via gas-atomization. At first, the alloy composition of Fe41Cr15Mo14C12B9Co7Y2 amorphous alloy with good glass forming ability was selected as the base alloy by adding with 3-7.5 w.t.% Al to improve its fracture toughness. The optimum result occurs at the modified Fe-based amorphous alloy with 3.5 wt.% Al addition (Fe43Co7Mo14Cr15C10B7.5Al3.5). The alloy hardness slightly decreased from 1200 to 925 HV and the fracture toughness was significantly improved from 4.78 ± 0.9 to 12.29 ± 0.9 MPa·m1/2. Moreover, the modified Fe-based amorphous alloy shows the minimum wear rate of 2.543 x 10-6 mm3/N·m among all samples in comparison with the alloy of SS316, SS420, SKDII, and the original Fe-based amorphous alloy. Secondary, the modified Fe-based amorphous alloy was fabricated into spherical alloy powder by gas atomization and characterized its amorphous status by X-ray diffraction (XRD). The XRD results revealed that a broaden peak accompanied the weak crystalline peaks of α-Fe and carbide phases occurred at the alloy powders with particle size under 90 μm, respectively. In parallel, the appearance of all these Fe-based alloy powders present a spherical shape and a solid cross-section. Hence, it is believed that this modified Fe-based amorphous alloy powder is suitable for MIM mold with conformal cooling channels by laser additive manufacturing. Keyword : Fe-based bulk metallic glass, fracture toughness, abrasion test, gas atomization, additive manufacturing
Appears in Collections:	[Graduate Institute of Mechanical Engineering] Electronic Thesis & Dissertation

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