In this work, six refractory nickel and cobalt-based cast alloys, rich in chromium and designed to be strengthened by tantalum carbides, were cast in controlled atmosphere. Samples were especially prepared to investigate their surface behavior in synthetic air at 1250 °C for three days. Their oxidized states were first characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) on surface, prior to following metallography processing. Second, oxides and subsurfaces were examined by SEM and energy dispersion spectrometry (EDS) on cross sections. Results show that the surface and subsurface deterioration by oxidation clearly depend on the relative quantities in Ni and Co in the chemical composition of the alloys. All alloys well-resisted oxidation due to their chromium contents, but beginnings of catastrophic oxidation were noticed for the alloys containing much more cobalt than nickel. Tantalum, present with particularly high contents, played an important role in the oxidation phenomena and for the microstructure stability at elevated temperature. It notably influenced the adherence of the external scale and led to highly stable heat-resistant TaC carbides, the fraction of which is governed by the base element.

在这项工作中，在受控的气氛中铸造了六种难熔的镍和钴基铸造合金，这些合金富含铬，并设计为由碳化钽增强。特别准备了样品，以研究其在1250°C的合成空气中三天的表面行为。在随后的金相处理之前，首先通过表面的X射线衍射（XRD）和扫描电子显微镜（SEM）表征其氧化态。其次，通过SEM和能量色散光谱法（EDS）在横截面上检查氧化物和地下。结果表明，氧化引起的表面和表面下的变质明显取决于合金化学成分中镍和钴的相对含量。所有合金的铬含量都能很好地抵抗氧化，但是，发现钴的含量远高于镍的合金开始出现灾难性的氧化。含量特别高的钽在氧化现象和高温下的微观结构稳定性方面起着重要作用。它显着影响了外部氧化皮的附着力，并导致了高度稳定的耐热TaC碳化物，其中一部分由基础元素控制。