THE ROLE OF SULFUR IN THE AIR EMBRITTLEMENT OF NICKEL AND ITS ALLOYS
THE ROLE OF SULFUR IN THE AIR EMBRITTLEMENT OF NICKEL AND ITS ALLOYS
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DOI：
10.1007/bf02645505
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发表时间：
1982-01-01
期刊：
影响因子：
--
通讯作者：
WOODFORD, DA
中科院分区：
文献类型：
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作者：
BRICKNELL, RH;MULFORD, RA;WOODFORD, DA
本文提出了镍及其合金在高温空气中脆化的机理。这种机制涉及硫化物的内部氧化为氧化物，伴随着脆化硫释放到晶界上。该机制显示在含MnS沉淀物的镍模型系统中起作用，其中在1000 °C的空气暴露200小时期间形成深度为250 µm的内氧化环。俄歇分析显示，在该区域内，晶界上的硫含量非常高，但在该区域之外，也显示出相当高的硫浓度。游离硫的大量释放导致合金在整个研究温度范围内（25至1000 °C）变脆。研究了这种机制对已知的纯镍（Ni 270）和镍基高温合金（IN 738）的空气脆化的贡献。虽然增强的O/Ni峰高比在两种材料的空气暴露的样品中观察到的，只有显着的硫浓度上观察到的表面上的晶界形成的空腔在Ni 270。然而，在这两种情况下，起始硫水平都极低，并且该机制可能导致其他系统中的高温空气脆化。
A mechanism leading to the embrittlement of nickel and its alloys following high temperature air exposure is proposed. This mechanism involves the internal oxidation of sulfides to oxides, accompanied by a release of embrittling sulfur onto the grain boundaries. The mechanism is shown to work in a model system of nickel containing MnS precipitates, in which a ring of internal oxidation 250 µm in depth forms during 200 hours air exposure at 1000 °C. Auger analysis shows very high sulfur levels on grain boundaries within this region, but also reveals considerable sulfur concentrations beyond it. This massive release of free sulfur had the effect of rendering the alloy brittle over the entire temperature range investigated (25 to 1000 °C). The contribution of this mechanism to the known air embrittlement of pure nickel (Ni270) and a nickel base superalloy (IN738) is investigated. Although enhanced O/Ni peak height ratios were observed in the air exposed samples of both materials, the only significant sulfur concentrations were observed on the surfaces of grain boundary cavities formed in Ni270. However, the starting sulfur levels were extremely low in both cases, and the mechanism may contribute to high temperature air embrittlement in other systems.