铁基电热合金丝显微组织均匀性的对比分析

电热合金的性能与合金成分、显微组织及织构存在密切关系。对两种成分的商用铁基电热合金丝(0Cr25Al5合金和0Cr21Al6Nb合金)样品的显微组织进行评测,重点分析了合金丝中显微组织的均匀性,探讨了合金元素、织构类型及合金丝径向不同位置处晶粒尺寸分布特征的关联关系。结果显示,与0Cr25Al5样品相比,含Nb的0Cr21Al6Nb样品表现出更为均匀的晶粒尺寸分布,且平均晶粒尺寸稍小。不同取向的晶粒在合金丝中的分布存在差异,<110>取向晶粒的平均晶粒尺寸较大,而小尺寸的<110>取向晶粒占比较小。同时,不同成分合金丝径向不同位置处晶粒尺寸分布均匀性存在差异,0Cr21Al6Nb样品晶粒尺寸分布跨度较小,不同位置差异不显著,即晶粒尺寸分布对位置不敏感;0Cr25Al5样品晶粒尺寸分布跨度较大,且合金丝不同位置晶粒尺寸分布不同。综上表明,添加碳化物形成元素能明显降低合金丝中平均晶粒尺寸及促进晶粒尺寸分布均匀性;晶粒取向与晶粒尺寸及其在合金丝中的分布存在一定关联性,可为电热合金丝制备工艺优化、显微组织改善与综合性能提升提供一定参考。

Contrastive analysis of microstructural heterogeneity of Fe-based electrothermal alloy wires

Property of electrothermal alloy is connected to its chemical composition, microstructure and texture. The microstructure of two commercial Fe-based electrothermal alloy wires (0Cr25Al5 alloy and 0Cr21Al6Nb alloy) was investigated, and the microstructural heterogeneity was analyzed with emphasis, then the relationship between chemical composition, texture, radial position of the alloy wire and the grain size distribution was discussed. The results show that comparing with 0Cr25Al5 alloy specimen, the 0Cr21Al6Nb alloy specimen containing Nb shows more homogeneous grain size distribution and lower average grain size. Different oriented grains show different size distribution, and <110> oriented grains have the higher average grain size, but small <110> oriented grains have the lower quantity. Moreover, the grain size distribution shows different dependence on the radial position in these two electrothermal alloy wires. The range of grain size value is lower in 0Cr21Al6Nb alloy specimen, and the grain size distribution is not sensible to the radial position. In comparison, much higher grain size value range is shown in 0Cr25Al5 specimen, and the microstructure varies at different positions. To conclude, it is deduced that the lower average grain size and more uniform microstructure could be achieved by the addition of carbide forming elements, and the relationship between chemical composition, texture, radial position and the grain size distribution of alloy wires could provide reference to the microstructure control and property optimization in electrothermal alloy production.