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在用铬投影的二级复型电镜照片上。常常会出现许多细小的黑点。有人称之为“麻点”。其图象特征是:黑点的边缘无亮影,它们非常象由样品上被粘附下来的污物或浸蚀产物,但是,即使再对原始样品进行许多次清洗(例如用AC纸揭膜清洗),仍然不能使麻点减少或消失。因此,又说明它们并非是污物。此类现象最典型的例子就是马氏体的自回火组织。“麻点”往往成为低碳马氏体发生自回火的代名词,麻点是微蚀坑?还是析出物?以前就有不同的说法,其确切答案一直不能用常规的复型法解决。如今,我们采用了钨投影法,针对25钢的马氏体进行电镜观察和摄照,解决了“麻点”之谜。原来,它们都是厚度在150A左右,直径在500至1000A的薄片。在原始金相样品上呈凸起。三维形态清晰可辨(见图2,3)。
On the second-level compound electron micrograph with chrome projection. There are often many small black spots. Some call it “pitting.” The features of the image are that the edges of the black spots are free of bright shadows which are very much like the dirt or etch products adhered to the sample but even if the original sample is cleaned a number of times Cleaning), still can not reduce or disappear the pock. So again, they are not dirties. The most typical example of such phenomena is the martensite self-tempering organization. “Pitting” often become synonymous with low-carbon martensite self-tempering, pitting is micro-etching pit? Or precipitation? Before there is a different argument, the exact answer has not been able to use conventional complex method to solve. Nowadays, we adopt the tungsten projection method to observe and photograph the martensite of 25 steel by TEM and solve the mystery of “pitting”. Originally, they are all about the thickness of 150A, the diameter of 500 to 1000A sheet. Protruding on the original metallographic sample. Three-dimensional shape clear and legible (see Figure 2,3).