本文用倒极图法研究了含0.5％Y和0.15％(La+Ce)稀土对Fe-Cr-Al合金在1200℃氧化时氧化层择尤取向的影响。 稀土元素对氧化层择尤取向类型的影响较小,三种合金的主要择尤取向都是(01(?)8),次要择尤取向有所区别:含稀土的合金是(11(?)9)、(10(?)10),不含稀土的合金是(0001)、(10(?)10)。稀土元素对增强和保持氧化层择尤取向的能力作用较大,其中Y比(La+Ce)的作用更为明显。 本文应用短路扩散位错通道的模型描述合金的氧化过程,使得氧化层的P_(10(?)1)系数曲线的变化和氧化动力学曲线的变化得到较好的吻合,这说明稀土元素的作用是通过改变氧化层的择尤取向来影响合金的抗氧化性能的。
The effects of RE additions, 0.5% Y or 0.15% (La+Ce), on the prefe ed orientation of oxide scale formed at 1200℃ in a Fe-Cr-Al alloy have been studied by inverse-pole-figure method. It was found that the addition of RE element affects the types of preferred orientation to a limited extent.The main preferred orientation in the oxide scale on three tested alloys are identical as (0118);whereas some differences are shown among their minor ones with (1129)and (10110) for alloys containing Y or La+Ce, and (0001) and (10110) for an alloy without RE. RE can play an important part in conserving and enhancing the preferred orientations in the scale, among which Y has a more remarkable effect than La+Ce.The oxidation process of the alloys was discribed by the shortcircuit dislocation path model. This model makes the variation curve of P_1011 parameter of the oxide scale in good agreement with the variation curves of oxidation dynamics. This accounts for the fact that RE elements improve the oxidation resistance of the alloy through their effect on modifying the preferred orientation of the oxide scale.
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