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研究了哈氏C-2000合金在800℃/100 h空气中等温氧化后合金基体中第二相的沉淀行为。氧化后基体中析出了富Mo相,可确定该富Mo相为具有金刚石结构的Mo3Ni3C型碳化物。富Mo相沿晶界和晶内分别呈现出非连续和连续条状形貌特征。然而,经深腐蚀后,晶内和晶界处形貌均发生了变化,即,沿晶界出现了大量白色絮状物,晶内则出现了具有金刚石结构的腐蚀坑。由于富Ni和富Cr区域具有更负的电极电位,因而使得这些区域在深腐蚀后更易被侵蚀。
The precipitation behavior of the second phase in Hastelloy C-2000 alloy after being isothermally oxidized in air at 800 ℃ for 100 h was studied. The oxide-rich matrix precipitates a Mo-rich phase, which confirms that the Mo-rich phase is a Mo3Ni3C carbide having a diamond structure. The Mo-rich phase presents discontinuous and continuous strip morphology along the grain boundaries and in the grain. However, after deep erosion, the morphologies of both the in-grain and in-grain boundaries changed, that is, a large amount of white flocs appeared along the grain boundaries and diamond-like corrosion pits appeared in the grains. Since Ni-rich and Cr-rich regions have more negative electrode potentials, these regions make them more susceptible to erosion after deep etching.