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首页> 外文期刊>Journal of Materials Engineering and Performance >Tensile Properties and Structure of Several Superalloys after Long-Term Exposure to LiF and Yacuum at 1173 K
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Tensile Properties and Structure of Several Superalloys after Long-Term Exposure to LiF and Yacuum at 1173 K

机译：长期暴露于LiF和Yacuum在1173 K下的几种高温合金的拉伸性能和结构

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摘要

The use of the solid-to-liquid phase transformation of LiF to store thermal energy Is under consideration for a space-based solar dynamic system. Although advantageous in terms of its energy density, the melt-Ing point of this salt (1121K) is beyond the commonly accepted upper-use temperature of 1100 K for chromium-bearing superalloys in vacuum. However, one commercially available nickel-base superalloy (Hastelloy B-2) is chromium free; unfortunately, because of its high molybdenum content, this alloy can form phases that cause high-temperature embrittlement. To test the suitability of Hastelloy B-2, It has been exposed to molten LiF, Its vapor and vacuum at 1173 K for 2500, 5000, and 10 h. For control, the chromium-containing cobalt-base Haynes alloy 188 and nickel-base Haynes alloy 230 were also exposed to LiF and vacuum at 1173 K for 5000h. Neither LIF nor vacuum exposures had any significant effect on Hastelloy B-2 in terms of mlcrostroctural surface damage or weight change. Measurement of the post exposure tensile properties of Hastelloy B-2, nevertheless, revealed low tensile ductility at 1050 K. Such embrittlement and low strength at elevated temperatures appear to preclude the use of Hastelloy B-2 as a containment material for LiF. Little evidence of significant attack by LiF was seen in either of the chromium-containing superalloys; however, considerable weight loss and near-surface microstructural damage occurred In both alloys exposed to vacuum. Although measurement of the post exposure room-temperature tensile properties of Haynes alloys 188 and 230 revealed no significant loss of strength or ductility, the severe degree of microstructural damage found in unshielded alloys exposed to vacuum indicates that chromium-bearing superalloys might also be unsuitable for prolonged containment of LiF in space above 1100 K.
机译：对于基于空间的太阳动力系统，正在考虑使用LiF的固液相转变来存储热能。尽管就能量密度而言是有利的，但该盐（1121K）的熔凝点超过了真空中含铬超合金通常可接受的1100 K的最高使用温度。但是，一种市售的镍基高温合金（Hastelloy B-2）不含铬。不幸的是，由于其高的钼含量，这种合金会形成引起高温脆化的相。为了测试Hastelloy B-2的适用性，将其暴露在熔融的LiF中，在1173 K的蒸气和真空下暴露2500、5000和10 h。为了进行控制，还将含铬的钴基海恩斯合金188和镍基海恩斯合金230暴露于LiF中，并在1173 K的真空下放置5000小时。无论是LIF还是真空暴露，对哈氏合金B-2的微结构表面损伤或重量变化均无明显影响。尽管如此，对Hastelloy B-2的暴露后拉伸性能的测量显示在1050 K下拉伸延展性低。这种脆性和在高温下的低强度似乎排除了将Hastelloy B-2用作LiF的密封材料的可能性。在两种含铬的超合金中，几乎没有证据表明LiF会引起严重的腐蚀。但是，两种暴露于真空中的合金都发生了相当大的重量损失和近表面微观结构破坏。尽管测量Haynes合金188和230的暴露后室温拉伸性能没有发现强度或延展性的显着降低，但是在暴露于真空的非屏蔽合金中发现的严重的微观结构破坏程度表明，含铬超合金也可能不适用于1100 K以上空间中LiF的长期密闭

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