6061-T6鋁合金與C1100銅合金摩擦攪拌異質焊接焊道微結構與鈰鹽化成處理研究

Abstract

本研究使用的材料為6061-T6鋁合金和C1100銅合金異質摩擦攪拌焊接試片，研究分為兩大部分，第一部分主要分析焊接後焊道區的表面與橫截面，透過化學蝕刻顯示焊道橫截面的材料流動，SEM觀察焊道區的微結構，並使用XRD與EBSD進行相鑑定。銅在焊接時被攪拌針攪拌脫落，產生銅顆粒流動到焊道區內部，焊道區橫截面主要分為鋁、銅界面與銅散佈於鋁基地的礦塊區，焊道區表面另有少數鋁在銅側的形貌，為材料垂直流動及鋁透過界面擴散的結果，在上述結構中發現介金屬相Al2Cu、AlCu與Al4Cu9在鋁、銅之間形成，呈典型擴散偶。 第二部分分別使用氯化鈰和硝酸鈰對6061-T6鋁合金與C1100銅合金基材與兩合金耦合試片進行化成，並使用OCP監控化成反應進行。氯化鈰化成在鋁合金上形成高覆蓋率的膜層，在銅合金上因氯離子的錯合形成不連續的膜層，耦合後因伽凡尼效應影響，鋁合金之化成膜覆蓋率降低，銅合金則生成鍵結弱的膜層。硝酸鈰將鋁合金鈍化，幾乎不產生膜層，而在銅合金上因硝酸根還原形成不連續的膜層，耦合後因鋁合金受到鈍化，對兩者產生的伽凡尼效應弱，結果耦合前後兩金屬產生的膜層於形貌上類似。最後透過動電位極化曲線結果指出，僅有氯化鈰在6061鋁合金上形成的膜層有提升抗蝕性的效果，與表面化成膜的覆蓋性有關，本研究所製成之其他膜層因為膜層不連續或附著性差而抗蝕效果不佳。

This study investigates the friction stir welding (FSW) of 6061-T6 aluminum alloy and C1100 copper alloy dissimilar joints. The research is divided into two main parts. The first part focuses on analyzing the surface and cross-section of the stir zone after welding. Chemical etching is used to reveal material flow in the cross-section, and SEM is employed to observe the microstructure of the stir zone. Phase identification is performed using XRD and EBSD. During welding, copper particles are stirred and scratched by the rotating pin, resulting in copper particle flow into the stir zone. The cross-section of the stir zone primarily consists of aluminum-copper interfaces and nugget zone which consists of copper particles dispersed in the aluminum matrix. Additionally, a small amount of aluminum is observed on the copper side of the plan view sample, resulting from vertical material flow and aluminum diffusion through the aluminum-copper interface. Intermetallic phases Al2Cu, AlCu, and Al4Cu9 are found to form between aluminum and copper, indicating typical diffusion couples. The second part involves cerium conversion coating using cerium (III) chloride and cerium (III) nitrate on the 6061-T6 aluminum alloy, C1100 copper alloy substrates, and coupled samples of both alloys. OCP is used to monitor the conversion reactions. Cerium chloride conversion can form a high-coverage film layer on the aluminum alloy and forms a discontinuous layer on the copper alloy due to the complexation of chloride ions, after coupling, the galvanic effect reduces the coverage of the conversion coating layer on the aluminum alloy, and a weakly bonded layer forms on the copper alloy. Cerium nitrate passivates the aluminum alloy, resulting in almost no layer formation, while a discontinuous layer forms on the copper alloy due to nitrate ion reduction, the galvanic effect is weak because the aluminum alloy is passivated, resulting in similar layer morphology on both metals after coupling. Finally, potentiodynamic polarization curves indicate that only the layer formed by cerium chloride on the 6061 aluminum alloy enhances corrosion resistance, which is related to the coverage of the conversion coating layer, other layers produced in this study do not exhibit corrosion resistance due to their discontinuous or poorly adherent nature.