| 摘要: | 本研究使用鐵基金屬玻璃Fe-Cr-Mo-C-B-Y-Co七元合金成分，以真空感應高週波爐將之融煉成合金鑄錠，再委由工研院以氣噴法製備成球型粉體。將粉體過篩並進行X光繞射分析、掃描式電子顯微鏡觀察等初步分析後，篩選合乎積層製造規範的粉體進行線型燒結測試與方塊燒結測試，以期設計出最適合粉體進行積層製造的製程參數。
將粉體過篩後，可得最大宗之粉體粒徑落於37~44μm間，從X光繞射分析結果中可以發現63μm以下的粉體皆為非晶質結構，而大於63μm粒徑的粉體則會有Cr23C6結晶相析出，且隨著粉體粒徑之上升， Cr23C6結晶峰之峰值也隨著提高。同時由SEM的觀察結果可以發現所有尺寸之粉體皆為球狀或近似球狀。
以OM觀察線型燒結基板後得到10組不同燒結功率與雷射掃描速率的參數組合，將該10組參數以及額外一組成功燒結麻時效鋼粉體的參數進行雷射重熔方塊測試，由所完成之雷射重熔方塊中可以發現大多數的方塊側面皆出現裂痕和剝落的現象，僅P240-S650(方塊7)、P240-S700 (方塊8)以及麻時效鋼粉體參數P320-S700(M)(方塊11) 所製方塊之外觀並無明顯缺陷。
然而，經由SEM觀察方塊7、8、11參數完成之雷射重熔方塊的內部結構及表面形貌，可以明顯看到方塊8和方塊11參數完成之雷射重熔方塊表面上仍有些許未完全熔融的粉末顆粒，且方塊11參數完成之雷射重熔方塊側面可以明顯地觀察到雷射重熔後粉層間未完全熔融的情形。雖然方塊7參數完成之雷射重熔方塊表面僅有極少粉末殘留側面且沒有明顯雷射重熔後粉層間分隔的情形，但有一裂紋貫穿整個試片表面與側面。方塊8參數完成之雷射重熔方塊表面僅有極少粉末殘留、側面也無明顯的雷射重熔後粉層間分隔情形，其表面與側面也無裂紋貫穿整個試片。同時也發現方塊8參數完成之雷射重熔方塊具有較高之維克式硬度，此說明了在相同材料下，因方塊8參數之雷射重熔後方塊其結構較其他兩者更為緻密，故擁有較高之硬度值，綜合上述結果後可以推論方塊 8參數為本研究中較佳的雷射重熔參數設定，可供未來進行雷射重熔鐵基非晶合金粉體製程條件之參考基準。
關鍵字: 鐵基金屬玻璃、氣噴法、雷射積層製造
;The alloy composition of Fe-Cr-Mo-C-B-Y-Co 7 components Fe-based alloy was selected as the master alloy and prepared by vacuum induction melting. Then the alloy ingots were re-melted and fabricated into spherical alloy powder by inert gas atomization process in the Material and Chemical Laboratories, Industrial Technology Research Institute (ITRI, Hsinchu). After size sieving, XRD analysis, and SEM examination, the atomized powders which can meet the specification of additive manufacturing were collected to do the linear laser melting test and cube selective laser melting (SLM) test. Hopefully, the optimum process parameters of SLM that is suitable for additive manufacturing can be designed.
After size sieving, the particle size of the most amount powder locates around 37~44 μm. According to the XRD results, all the powders which particle size below 63 μm are confirmed to be amorphous. On contrary, the structure of the powders with particle size more than 63 μm was found to contain an amorphous matrix co-existing with a C23C6, crystalline phase. The intensity of the C23C6 peak increases with increasing the powder size. Meanwhile, a spherical or near-spherical appearance can be clearly observed by SEM examination for all powders.
10 sets parameters of laser power and scanning rate were obtained from the results of linear laser melting test by OM observation. Then these 10 sets parameters and an additional parameter (which can successfully apply on produce maraging steel sample) were applied to do the cube SLM test. After SLM, cracks and spalls were found on the side view of most SLM cubes except the cubes made by the parameters of P240-S650 (#7), P240-S700(#8), and the parameter for maraging steel (#11). However, after the SEM examination on the cube samples made by parameters of #7, #8, and #11, respectively, there still can be found several unmelted powder particles on the surface of cube sample which made by the parameters of #8 and #11. In parallel, the laser melted powder layers of the cube sample made by # 11 parameter exhibit an insufficient fusion condition and the separated powder particles still can be seen on the side view of cube sample. Although there are no unmelted powder on the cube surface and no insufficient fusion condition on the side view for the cube sample made by #7 parameter, but there is one crack throughout the whole cube sample. On the other hand, there are only few unmelted powder particles on the sample surface, no clear separation of laser melted powder layers, and no obvious creaking can be found in the cube sample made by #8 parameter. Moreover, the cube sample made by parameter #8 presents higher hardness than the samples made by the parameters of #7 and #11, which means that the cube sample made by #8 parameter possesses higher product density than the other. In summary, #8 parameter seems the optimum process condition in this study and can be applied as the reference for the further laser additive manufacturing the Fe-based amorphous alloy.
Keyword: Fe-based metallic glass, atomization process, additive manufacture |
