基于微束X射线荧光光谱的粉末冶金高温合金成分定量分布分析及应用

粉末冶金高温合金中元素偏析以及粉末原始颗粒边界是影响材料性能的重要因素，由于其颗粒粒径通常为几十微米，宏观的成分分布分析方法无法实现粉末原始颗粒边界处成分分布的精细表征。微束X射线荧光光谱（μ-XRF）是近年来发展起来的无损微区成分分布分析技术，可实现材料较大范围内元素快速、高分辨分布分析，目前在地质、考古、生物等领域有了较多的应用，但在复杂块状金属成分定量分布表征方面还存在一定困难，在粉末冶金工业领域还未见有应用报道。该试验研究了高温合金中各元素的荧光光谱行为，通过类型匹配的高温合金块状标准样品对元素定量模型进行了校正，建立了基于μ-XRF的高温合金成分定量分布分析方法，满足了粉末冶金工业对于较大范围内粉末边界成分分布精细定量表征的需求。该实验以经高纯钴合金化处理的放电等离子体烧结（SPS）粉末高温合金样品为研究对象，对经不同球磨时间混合处理后的粉末烧结样品中的Ni，Co，Cr，Mo，W，Ta，Ti和Al进行了定量统计分布分析，探讨了不同球磨时间对烧结样品成分分布的影响规律；发现样品中存在大量原始颗粒边界，且成分分布较不均匀，颗粒中心处仍然为原始高温合金颗粒成分，经球磨混合加入的纯Co粉颗粒仅存在于高温合金颗粒的外层，导致颗粒边缘Co含量明显高于颗粒中心。当球磨时间较短时，原始颗粒边界处存在很多Co富集区，当球磨时间增加到24 h时，由于在机械混粉过程中超细钴粉与高温合金的合金化，使烧结样品成分分布均匀性有了较大改善，原始颗粒边界处Co的含量显著下降，而其他元素的含量有所增加，说明球磨时间的延长，样品中各元素发生了明显的扩散，这将有助于元素偏析的改善，据此，该粉末冶金高温合金的制备工艺将得以改进。该法亦可应用于其他各种粉末冶金工业产品的成分定量分布表征，可为粉末冶金工艺优化、产品质量的改进提供数据支撑。

Quantitative Distribution Analysis of P/M Super Alloy Composition Based on Micro Beam X-Ray Fluorescence Spectroscopy and Its Application

The segregation of elements and the original particle boundary of powder metallurgy superalloy are the important factors affecting the material properties.Because the particle size is usually tens of microns,the traditional analysis method of composition distribution can not realize the fine characterization of the composition distribution at the original particle boundary of powder metallurgy superalloy.Microbeam X-ray fluorescence spectrometry(μ-XRF)is a non-destructive micro area composition distribution analysis technology developed inrecent years.It can realize the rapid and high-resolution distribution analysis of elements in a wide range of materials.At present,it has been widely used in geology,archaeology,biology and other fields.However,there are still some difficulties in the quantitative distribution and characterization of complex block metal composition,which has not yet been applied in the powder metall urgy industry.In this study,the fluorescence spectrum behavior of each the element in superalloy was studied.The quantitative model of element was corrected by the type matching bulk standard sample of superalloy.The quantitative analysis method of composition distribution of Superalloy based onμ-XRF was established,which met the needs of powder metallurgy industry for fine quantitative characterization of powder boundary composition distribution on a large scale.The SPS powder superalloy samples treated by high purity cobalt alloying were taken as the research object.The quantitative statistical distribution of Ni,Co,Cr,Mo,W,Ta,Ti and Al in the powder sintered samples after different milling time were analyzed.The influence of different milling time on the composition distribution of the sintered samples was discussed.The results show that there are a large number of original particle boundaries,and the composition distribution is not uniform.The pure Co powder particles added by ball milling on ly exist in the outer layer of superalloy particles,resulting in the Co content at the edge of particles is significantly higher than that in the particle center.When the milling time is short,there are many Co enrichment areas at the boundary of the original particles.When the milling time is increased to 24 h ours,due to the alloying of ultra-fine cobalt powder and superalloy in the process of mechanical mixing,the composition distribution uniformity of sintered samples is greatly improved,and the content of Co at the boundary of original particles decreases significantly,while the content of other elements increases.The results show that the diffusion of each element in this sample is obvious,which is helpful to the improvement of element segregation.Therefore,the preparation process of the powder metallurgy superalloy is improved.This method can also be used to characterize the composition distribution of other P/M industrial products and provide data support for the optimization of P/M process and the improvement of product quality.