- 學位論文
結晶鋯銅基塊狀金屬玻璃複材雷射非晶化改質之研究
Laser amorphous fabrication of a matrix-crystallized Zr-Cu based bulk metallic glass composite
摘要
本研究針對以緩冷凝固製備且基地結晶(Zr48Cu32Al8Ag8,Ta4)Si0.75 金屬玻璃複材(約1.0mm 厚度)，以Nd:YAG 雷射進行重融非晶化改質，以確認基地結晶的金屬玻璃複材的可再利用。研究範圍共分兩階段工作，第一階段計畫目的為驗證Nd:YAG 雷射是否能達到結晶金屬玻璃複材非晶化的表面改質，第二階段計畫將採用更高的雷射能量，則希望將改質條件由表面延伸至成整塊塊狀金屬玻璃複材(1.0mm 厚度)基地非晶化的改質。經雷射改質後的試片隨後與鑄造結晶試片(MC-BMGC)、鑄造基地非晶試片(IMA-BMGC)進行顯微組織觀察、機械性質 (微小維氏硬度)、熱物性質以及抗腐蝕性 (電化學量測)等比對測試。 實驗結果顯示，MC- BMGC 經過雷射表面非晶化(LSAF-BMGC)或整體非晶化(LWBAF-BMGC)改質處理過後，經改質的區域基地非晶化程度相似於IMA-BMGC 試片，但LSAF-BMGC 及 LWBAF -BMGC 在改質後基材內部的Ta 強化相體積分率有明顯下降的趨勢。而兩者經由DSC 量測的熱物性質GFA 指數 ΔTx 顯示在改質後有小幅度的上升，但γ、 γm 較無太大改變；機械性質發現Ta 強化相的次微米化，並不會影響非晶態硬度值的改變；而電化學測試結果發現經過雷射改質後誘發腐蝕的機率較高，其原因可能與銲點周圍的應力導致優先腐蝕，但由於Ta有重熔且尺寸下降的現象，降低了孔蝕及Ta 邊界腐蝕的腐蝕速度。
關鍵字
none並列摘要
To confirmed that the matrix-crystallized bulk metallic glass composite (MC-BMGC) could be recycled, in this study, a matrix crystallized in-situ (Zr48Cu32Al8Ag8,Ta4)Si0.75 plate (1.0 mm thick) was amorphously fabricated by employing the Nd:YAG laser re-melting technique. This project consists of two stage works. At the first stage, the surface of MC-BMGC was firstly test by using Nd:YAG laser surface re-melting technique. If the surface of the MC-BMGC becomes matrix-amorphous, at the second stage, the whole block of MC-BMGC is amorphous fabricated using a higher energy. The microstructure, hardness, the thermal properties and corrosion resistance of the laser surface amorphous fabricated BMGC (LSAF-BMGC) and laser whole block amorphous fabricated BMGC (LWBAF-BMGC) were investigated and compared to those of the MC-BMGC, initial matrix amorphous BMGC (IMA-BMGC) cast. The test results show that, after LSAF or LWBAF processes, both samples consist of an amorphous matrix in all re-melted area, which are similar to IMA-BMGC, but the volume fractions of the micro-sized reinforced phase, Ta, in LSAF-BMGC and LWBAF-BMGCs are reduced. When compared to those of IMA-BMGC, the GFA indices, ΔTx, of those re-melting BMGCs are improved. For the hardness tests, after laser modified, LSAF-BMGC and LWBAF-BMGC show that no significant effect when compared to those of MC-BMGC and IMA-BMGC. Furthermore, both LSAF-BMGC and LWBAF-BMGCs exhibit the better corrosion resistance which is attributed to the amorphous matrix and the less micro-sized Ta content.