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用TGA、OM、SEM和HREM等方法研究了Cu含量不同的几种AgCu合金在750℃及850℃的内氧化行为。发现氧化12h后,Ag-0.8at％Cu合金中的Cu已完全以CuO颗粒析出;含有3.3和6.3at％Cu的合金还没有完全被内氧化;这三种样品表面析出较均匀的CuO颗粒,而Cu含量过高(≥9.5at％)时的合金表面形成含有大量CuO颗粒簇的隆起物。从内氧化层的截面形貌看,750℃下的Ag-0.8at％Cu、Ag-3.3at％Cu,850℃下Ag-0.8at％Cu合金内氧化时单位体积内析出的CuO颗粒密度随内氧化深度增加而降低,而其它试验条件下没有类似变化。通过对内氧化AgCu合金的原子结构进行观察,发现其中存在一定密度的空位型堆垛层错四面体(SFT),认为这些SFT是氧化过程中由“Kirkendall”空位聚集形成的空位型层错。它在内氧化前沿产生,促进了Cu的扩散以及CuO的形核。提出了导致内氧化物在合金内氧化层均匀析出的途径。
The internal oxidation behavior of several AgCu alloys with different Cu contents at 750 ℃ and 850 ℃ was studied by means of TGA, OM, SEM and HREM. It was found that after oxidation for 12h, the Cu in Ag-0.8at% Cu alloy precipitated completely as CuO particles; the alloy containing 3.3 and 6.3at% Cu was not fully oxidized; CuO particles were precipitated on the surface of these three samples, On the other hand, when the content of Cu is excessively high (≥9.5 at%), bumps with a large amount of CuO particle clusters are formed on the surface of the alloy. From the cross-sectional morphology of the inner oxide layer, the density of CuO particles precipitated per unit volume at 750 ° C under Ag-0.8at% Cu, Ag-3.3at% Cu, and within Ag-0.8at% Cu alloy at 850 ° C The depth of internal oxidation increased and decreased, while no similar changes were observed under other experimental conditions. By observing the atomic structure of the AgCu alloy, we found that there is a certain density of vacancies in the stacking fault tetrahedra (SFT). These SFTs are considered as vacancy faults formed by the “Kirkendall” vacancy aggregation in the oxidation process. It is generated in the internal oxidation front, promoting the proliferation of Cu and CuO nucleation. The approach leading to the uniform precipitation of the inner oxide within the oxide layer of the alloy was proposed.