本研究透過觀察微結構及機電性質，探討通電對6061鋁合金性質變化的影響與機制。本實驗所使用的6061鋁合金是經過過時效處理之試片，以電流密度6400 A/cm2對其通電3-60分鐘，量測不同通電時間對材料微結構、維氏硬度及電阻率的變化，並結合微結構的變化和機、電性質，分析影響材料性質的機制。X光繞射分析顯示電流使材料內部產生應變，但並沒有發生相轉換。掃描式電子顯微鏡分析顯示通電前後析出物數量及尺寸的變化；穿透式電子顯微鏡觀察材料結晶面發現鋁基地相(111)面及(200)面差排密度隨通電時間不同有所增減。藉由電子背向散射繞射分析顯示材料在通電後，(101)為擇優取向；晶界取向差角的分析顯示，高低角度晶界比例變化不明顯，顯示再結晶及凝核等現象不明顯；晶粒尺寸亦無明顯變化。通電後微硬度變化受到差排密度變化影響，差排密度的變化推測是析出物造成的結果，電阻率也同樣與差排密度變化關聯性較大。

This study investigated the variation of mechanical and electrical properties and microstructure of 6061 aluminum alloy after current stressing. The over-aged specimens were subjected to direct current stressing at 6400 A/cm2 for 3-60 minutes. After current stressing, the specimen was quenched with liquid nitrogen immediately to eliminate the residual joule heat on microstructure. The variation in microstructure, Vickers hardness and electrical resistivity were investigated with respect to current stressing time. The results of XRD investigation showed that strain was generated but no obvious phase transformation occurred. SEM images indicated that precipitates were found in the matrix. The results of TEM investigation showed that the lattice orientation and the dislocation densities in the matrix changed. EBSD results indicated that the preferred orientation was (101). The misorientation angle did not change a lot, grain size of matrix also changed little, indicating no obvious grain growth and recrystallization. The variation of microhardness and electrical resistivity was greatly related to the variation of dislocation density of (111).

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