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本文指出,适量的La能显著提高Ni-20Cr-20Co-18W高温合金1000℃、4kg/mm~2的持久性能和蠕变激活能。La在该合金中的最佳含量为0.01～0.04wt.％。用离子探针、俄歇谱仪、扫描电镜、透射电镜等仪器研究发现,La主要富集在晶界上,有些La形成了氧化物和氧硫化物,一些La的氧化物可成为M_6C碳化物的核心,当La含量超过0.04wt.％后,还出现Ni_xLa等金属间化合物。用热蚀刻方法测量了合金的晶界能。用测量电阻率随温度变化的方法测得了合金的空位形成能。从理论上阐述了La降低晶界能和提高空位形成能的作用是改善合金持久性能的主要原因。
This paper points out that the proper amount of La can significantly improve the persistence and creep activation energy of Ni-20Cr-20Co-18W superalloy at 1000 ℃ and 4kg / mm ~ 2. The optimum content of La in the alloy is 0.01 to 0.04 wt.%. With ion probe, Auger spectroscopy, scanning electron microscopy, transmission electron microscopy and other instruments found that La mainly enriched in the grain boundary, and some La oxide and oxysulfide oxide, some La oxide can be M_6C carbide When La content exceeds 0.04 wt.%, Ni_xLa and other intermetallic compounds also appear. The grain boundary energy of the alloy was measured by thermal etching. The vacancy formation energy of the alloy was measured by measuring the change of resistivity with temperature. It is theoretically explained that the effect of La on reducing the grain boundary energy and increasing the vacancy formation energy is the main reason for improving the long-term durability of the alloy.