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为了保持低的膨胀系数，低膨胀ＧＨ９０９合金中不含Ｃｒ，导致合金的抗氧化性能较差为了解决这一问题，在ＧＨ９０９合金的基础上调整成分，加入少量Ｃｒ和稀土元素Ｙ与Ｌａ等，并提高Ｃｏ／（Ｃｏ＋Ｎｉ）比例，使合金在膨胀系数基本未变的情况下，抗氧化性能得到较明显的改善用Ｘ射线衍射、金相显微镜、扫描电镜等检查了合金的氧化层，发现ＧＨ９０９合金氧化层很厚，其主要成分为Ｆｅ_３Ｏ_４， Ｆｅ_３Ｏ_２等，氧化层组织较疏松，有内氧化现象加入Ｃｒ和稀土元素的合金氧化层较薄，氧化层主要成分还有Ｃｒ_２Ｏ_３等，氧化层组织致密，未见内氧化。温度愈高，Ｃｒ和稀土的有益效果愈明显，它们有效地抑制了氧的扩散。
In order to maintain a low coefficient of expansion, low expansion GH909 alloy does not contain Cr, resulting in poor oxidation resistance of the alloy In order to solve this problem, GH909 alloy based on the adjustment of composition, adding a small amount of Cr and rare earth elements Y and La, And improve the ratio of Co / (Co + Ni), so that the alloy under the condition of substantially unchanged expansion coefficient, the oxidation resistance was significantly improved by X-ray diffraction, metallographic microscope, scanning electron microscopy examination of the alloy oxide layer found GH909 The alloy oxide layer is very thick, its main components are Fe 3 O 4, Fe 3 O 2 and so on, the oxide layer is loose, the oxidation layer is Cr oxide and rare earth element alloy oxide layer is thinner, the oxide layer is mainly composed of Cr 2 O 3, the oxide layer is dense , No internal oxidation. The higher the temperature, the more beneficial the effect of Cr and rare earth, they effectively inhibit the diffusion of oxygen.