Please use this identifier to cite or link to this item:
標題: 體心立方Mg-Li合金相之形成與該材料Li、Na、K成分控制之研究-以非傳統方式之電解擴散法備製Mg-Li-Al-Zn合金
The Investigation of the Phase Formation of Body Centered Cubic Mg-Li Alloy and the Composition Control of Li, Na, K Element- A Non-Traditional Preparation Process of Mg-Li-Al-Zn Alloy by Electrolytic Diffusing method
作者: 林孟昌
Lin, Meng-Chang
關鍵字: Magnesium-Lithium
AZ91 alloy
Electrolysis Diffusion
Master Alloy
出版社: 材料工程學研究所
摘要: Mg-Li-Al-Zn合金可以於500C的電解液(55wt%的氯化鉀+45 wt%的氯化鋰)中,在大氣環境下利用電解擴散法備製之。電解擴散試驗時,Mg-9Al-1Zn (AZ91) 合金為陰極,石墨為陽極。由實驗結果可以得知,電解電流跟施加的工作電壓呈現線性關係。施加一定電壓後,鋰原子開始在陰極表面上沈積;電解實驗後,利用ICP、XRD、OM、SEM等技術來分析生成的Mg-Li相。影響陰極試片鋰含量的因素中;擴散因素的影響要比沈積速度因素(電解電流)來的大。最後在工作電壓4.2V,電解時間為一個小時的條件下,AZ91的合金板材(1.5mm)會由原來的HCP結構全部轉換成BCC結構,經過分析後其鋰含量為12wt%,鈉跟鉀含量卻分別只有0.007wt%跟0.13wt%,由於受到不同合金元素在鎂中之固溶度不同與β-Mg相生成的影響,陰極試片中鈉及鉀的含量會遠低於鋰含量。另外,利用電解擴散法備製的Mg-12Li-9Al-1Zn母合金,嘗試於大氣環境下熔煉與鑄造成Mg-Li合金,可以在不產生任何燃燒現象的情形下,於大氣環境中在SF6的保護氣氛中進行熔煉。但是,由於熔煉過程中鋰產生蒸氣揮發的情形,造成鑄錠中的鋰含量下降至3.77wt%。厚度為3mm的AZ91合金(HCP結構),透過控制電解電流的方式進行電解擴散後,可以得到厚度為4.6mm Mg-13Li-9Al-1Zn合金板材(BCC結構)。此鎂鋰鋁鋅合金板材可以在常溫下壓延成1.5mm的 薄板,延伸率可達到22%,比AZ91D合金高出七倍以上。
Electrolytic diffusing method was conducted at 500C to prepare Mg-Li-Al-Zn master alloy in air. A mixture of 45 wt% lithium chloride (LiCl) and 55 wt% potassium chloride (KCl) was employed as the electrolyte. Mg- 9wt% Al- 1wt% Zn (AZ91) alloy was used as cathode material while graphite selected as anode. Experimental results showed that the electrolysis current linearly depended on the applied working voltage. Deposition of lithium occurred on the cathode surface. At working voltage of 4.2 V and one hour electrolysis, the hexagonal-closed-pack AZ91D sheet (1.5-mm thickness) was fully converted to body-centered-cubic Mg-Li-Al-Zn alloy. After the electrolysis experiments, Mg- 12wt% Li- 9wt% Al- 1wt% Zn alloy sheet can be obtained. The formation of Mg-Li phase during electrolysis was studied by inductively coupled plasma-atomic emission spectrometer (ICP), X-ray diffraction, and optical microscopy. It is diffusion rather than deposition rate (electrolysis current) that controlled the depth of Mg-Li phase formed in the cathode sample. Solubility of different element and the formation of β-Mg phase was reduced the content of sodium and potassium in Mg-Li-Al-Zn cathode material. It was also explored for the melting and casting of Mg-Li alloy in air, as the Mg-Li-Al-Zn master alloy used as raw material. The Mg-Li-Al-Zn alloy used as master alloys could be melted and casted in air without ignition. However, the content of lithium in the as-cast block was reduced to 3.77 mass %, properly due to evaporation of lithium metal during melting. After electrolysis experiments, the Mg-13Li-9Al-1Zn alloy plate can be obtained, the hexagonal-closed-pack AZ91 plate (3mm in thickness) was fully converted to the mixture of α-Mg and BCC Mg phase (4.6mm in thickness). The Mg-13Li-9Al-1Zn alloy plate (thickness changed to 4.6mm) could be cold rolled into 1.5mm strip, After heat treatment, the Mg-13Li-9Al-1Zn alloy strip exhibits elongation ~ 22%, which is 7 times more than the AZ91D alloy.
Appears in Collections:材料科學與工程學系



Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.