本研究透過觀察微結構、機械性質與電性，探討通電對純銅雙晶生成與性質影響之機制。本實驗對純銅薄帶施以1.4x104A/cm2及1.7x104A/cm2的電流密度通電1到8小時，量測不同通電條件下微硬度與電阻率變化，並結合微結構的變化分析影響材料性質之機制。光學顯微鏡分析顯示通電會使純銅發生晶粒旋轉與生成新的雙晶；X光繞射分析顯示通電會使材料內部產生應變；電子背向散射繞射分析顯示純銅通電後會使雙晶晶界比例上升，雙晶晶界總長度隨通電時間增加呈現先增後減的趨勢，契合型雙晶晶界比例在通電1小時先增加而後隨通電時間增加呈現先減後增的趨勢，晶粒大小在通以1.4x104A/cm2的電流密度下是先減後增，通以1.7x104A/cm2的電流密度下則是上下震盪，在8小時才有明顯增加；穿透式電子顯微鏡分析顯示在相同通電時間下，靠近雙晶晶界處之差排密度大於遠離雙晶晶界處，且通以1.4x104A/cm2的電流密度大於通以1.7x104A/cm2的電流密度。通電後微硬度值的變化與差排密度及雙晶晶界比例有高度關聯性，電阻率則是與雙晶晶界比例有高度關聯性。

This study investigated the mechanism of the properties and microstructure variation on pure copper after current stressing. The strip specimens were subjected to 1.4x104A/cm2 and 1.7x104A/cm2 direct current stressing for 1-8 hours. The specimens were rapidly quenched with liquid nitrogen after current stressing to freeze the microstructure for investigation. The variation in microhardness, electrical resistivity and microstructure were discussed with different current stressing parameter. OM results showed that grain rotation and new twin generation occurred. XRD results showed that electric current induced lattice strain. EBSD results indicated that twin fraction increased after current stressing. The twin length showed the trend of first increase and then decrease with the increase of current stressing time. The coherent twin fraction increased initially and then showed the trend of first decrease and then increase with the increase of current stressing time. The grain size which subjected to 1.4x104A/cm2 showed the trend of first decrease and then increase with the increase of current stressing time. The grain size which subjected to 1.7x104A/cm2 showed no obvious trend, but there was significant increase after current stressing for 8 hours. TEM observation showed that the dislocation density near the twin boundary was greater than that away from twin boundary and the dislocation density subjected to 1.4x104A/cm2 was larger than that subjected to 1.7x104A/cm2 after current stressing for the same time. The major variation of microhardness was governed by the change of dislocation density and twin fraction. The variation in electrical resistivity was highly related to twin fraction.

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