(西北工業(yè)大學 航空學院，西安 710072)
摘 要: 利用數(shù)字圖像相關(guān)法研究了垂直晶界銅雙晶試樣的拉伸變形行為，獲得了拉伸過程中試樣表面的全場變形分布。結(jié)果表明：試樣整體變形呈“雙頸縮”現(xiàn)象，試樣表面的應(yīng)變分布不均勻，晶界附近的應(yīng)變水平低于晶粒內(nèi)部的，試樣總是在軟取向的晶粒內(nèi)首先發(fā)生塑性變形并斷裂。借助掃描電鏡(SEM)原位拉伸實驗觀察到在拉伸過程中滑移帶不能穿過晶界。以上結(jié)果說明，銅雙晶試樣拉伸變形行為與組元晶粒的晶體取向和晶界的屬性有關(guān)，軟取向的晶粒更容易發(fā)生塑性變形，而大角度晶界在拉伸過程中具有強化效應(yīng)，對晶粒的滑移變形有阻礙作用。
關(guān)鍵字: 銅雙晶；晶界；連鑄單晶銅；數(shù)字圖像相關(guān)法；微拉伸
（School of Aeronautics, Northwestern Polytechnical University, Xi’an 710072, China）
Abstract:The tensile deformation behavior of a copper bicrystal with a perpendicular grain boundary was investigated using digital image correlation (DIC) method, and the whole field deformation distribution on the specimen surface during the tensile test was obtained. The results show that the specimen is deformed in the “double necking” shape. The strain distribution on specimen surface is inhomogeneous, and strain level at the grain boundary is lower than that in the interior of grains. The specimens fracture within the grain with soft orientation. The in-situ tension by scanning electron microscopy (SEM) indicates that slip bands cannot pass through the grain boundary. The above results suggest that the tensile deformation behavior of the copper bicrystal is determined by the orientation of each grain and the property of grain boundary. The grain with soft orientation tends to deform plastically and fracture first. Large-angle grain boundary can impede slip bands and hence strengthen the material.
Key words: copper bicrystal; grain boundary; continuous casting single crystal copper; digital image correlation (DIC) method; micro-tensile
