| 摘要: | 在塊狀非晶質合金中，添加金屬顆粒均勻的分佈在基地裡扮演障礙物的角色，可以有效地阻止剪切帶的傳播進而阻止材料被破壞，大幅提升非晶質合金的塑性。本研究在鋯-鋁-鈷非晶質合金中添加微米等級的鉭顆粒 (5 ~ 30 µm)金屬顆粒，利用鉭之高熔點與韌性作為散佈強化之金屬顆粒，藉此來增加本合金系統之塑性。
從XRD結果顯示添加0~2.5 vol.%的鉭顆粒之鋯-鋁-鈷塊狀非晶質合金均為非晶態，而添加超過2.5 vol.%則為結晶。隨著鉭添加量上升，結晶溫度(Tx)隨之下降且過冷液相區間(ΔTx)從53減少為43 K，γm從0.684(1 vol.%)微幅下降到0.671(2 vol.%)，顯示鉭的添加使得玻璃形成能力下降。綜合熱分析結果可以得知，隨著鉭顆粒添加量越高，熱穩定性與玻璃形成能力越差。以SEM觀察試片橫截面無法明顯的觀察到鉭顆粒的存在，但在EDS的分析結果中發現與合金成份((Zr54Al17Co29)100-xTax)相符，證實了SEM觀測不到鉭顆粒是由於鉭已經與基材熔融在一起。(Zr54A17Co29)99Ta1在本合金系統中具有最佳機械性質，其硬度為525 ~ 545 Hv之間、真實降伏強度為2400 MPa、破裂強度為2927 MPa。塑性變形量隨著鉭添加量增加從1%到2%而有明顯的遞減的趨勢，由8.48%(1 vol.%)降至0.87%(2 vol.%)，同時，從TEM圖中可以觀察到在鉭含量2 vol.%的成分中具有奈米晶的存在，推測其局部分布影響了棒材之機械強度。另外於Hank’s Balanced Salt Solution中進行腐蝕測試發現(Zr54A17Co29)99Ta1具有優於316SS的抗腐蝕性。
;Based on the concept of dispersion toughening on the Zr-based bulk metallic glass (BMG) by adding Ta particles, a series of ZrAlCo-based bulk metallic glass composites (BMGCs) rods (2 mm in diameter) with 1-2 vol.% Ta particles (size of 5-30µm) have been successfully fabricated by arc-melting and suction casting.
The characterization of amorphous state, thermal properties, microstructure, mechanical properties and anti-corrosion ability were conducted by XRD, DSC, Vicker’s hardness tester, universal test machine, and Potentiostat, respectively.
The XRD results show that all the ZrAlCo alloy rods with 1-2.5 vol.% Ta particles are amorphous state, but the ZrAlCo alloy rods with more than 2.5 vol.% Ta particles are crystallized. According to the DSC results, the BMGC with the higher Ta additions presents lower crystallization temperature (Tx) and supercooled liquid temperature region (ΔTx). In parallel, the ΔTx decreasees from 53K (1 vol. %) to 43 K (2 vol. %). Moreover, the glass forming ability (GFA) decreases with increasing the Ta additions. Therefore, it is difficult to obtain an amorphous matrix when the additions of Ta particle is higher than 2 vol%.
The optima results of mechanical performance of the ZrAlCo BMGC occurs at Zr54A17Co29 with 1 vol.% Ta addition, the yield strength, fracture strength and plastic strain are2400 MPa, 2927 MPa and 8.48 % respectively. Furthermore, the Zr54A17Co29 with 1 vol.% Ta addition shows the best corrosion resistance in Hank’s Balanced Salt Solution. |
