High-throughput And Statistical Method Of Cross-scale Gamma Prime Precipitates In Polycrystalline Superalloy And Its Characteristical Application

γ’ precipitates in superalloys is one of the key factors to excellent mechanical properties at high temperature,its size,quantity,area distribution,morphology,size distribution will affect the properties of the alloy,so it is necessary to carry out quantitative statistics of γ’ precipitates.γ’ precipitates in superalloys has a wide size distribution range(from a few nanometers to more than ten microns),a large number of different,resulting in a difficult characterization.At present,the simultaneous characterization of primary,secondary and tertiary γ’ precipitates and corresponding representative quantitative statistical data cannot be achieved by two or more analytical methods.For that reasons,it is meaningful and necessary to establish a new quantitative statistical characterization method of γ’ precipitates.In this paper,based on the idea of high-throughput characterization of Material Genome Engineering,a high-throughput field emission scanning electron microscope method for quantitative statistical characterization of cross-scale γ’ precipitates was established for the quantitative characterization of cross-scale γ’ precipitates.The problem of images obtaining,features identifying and recognition of primary,secondary and tertiary γ’ phases in polycrystalline superalloys has been solved.By establishing the minimum statistical field of view,the multi-parameter cross-scale quantitative characterization was realized.For the first time,the quantitative and statistical information of primary,secondary and tertiary γ’ precipitates in superalloy components was obtained by a single experiment using the high-throughput scanning electron microscope.Through the ratio of primary γ’ precipitates area fraction,the ratio of secondary and tertiary γ’ precipitates number,and the area fraction of secondary and tertiary γ’precipitates with the number of images,the minimum field of view for obtaining quantitative statistical data of γ’ precipitates was obtained: 13 × 13 representation regions of 57000 times images with 2048 × 2048 pixel size.The results of minimal region characterization were consistent with the results of primary γ’ precipitates distribution by traditional optical microscope method,electrolysis extraction and small angle X-ray scattering method.The γ’ precipitates of GH4096 under different simulated cooling processes was characterized by a high throughput scanning electron microscope method for quantitative statistical characterization of γ’ precipitates at different scales.The size distribution and quantitative change of γ’ precipitates in the solution state and the aging state of samples with different cooling rates are discussed and compared.The trend of the change of γ’ precipitates with the cooling rate and the quantitative change of γ’precipitates in the solution state and the aging state are found.When the solution cooling rate is between 70 ℃/min and 100℃/min,the high temperature tensile strength and plastic properties of the sample are the best.The GH4096 baffles under three different processes of air cooling,air cooling and salt bath cooling were studied by using the cross-scale high throughput scanning electron microscope method established in this paper.The quantity and size of γ’precipitates at each position of the baffles were quantitatively characterized.The results show that the size range of γ’ precipitates in GH4096 superalloy is 50-90 nm and 10-15 nm,respectively,and the size range of γ’ precipitates in actual sample is 20-25 nm due to the comprehensive influence of size effect and process process.In addition,γ’precipitates is very sensitive to small changes in the cooling rate of solution.Under the same technological conditions,the cooling rate of subsolid solution treatment has a great influence on the amount,average diameter and area fraction of γ’ precipitates produced in this process,and this influence still exists in the formation and growth ofγ’ precipitates during the subsequent aging treatment.In this paper,a high-throughput field emission scanning electron microscope method for quantitative statistical characterization of cross-scale γ’ precipitates was established and applied to γ’ precipitates characterization in large size samples.Representative quantitative statistical results of primary,secondary and tertiary γ’precipitates of polycrystalline superalloys can be obtained through a single highthroughput scanning electron microscope experiment and post analysis.The method has been applied to the basic research of superalloy under different technological conditions,and the results of γ’ precipitates characterization is fast and accurate.The established high-throughput scanning electron microscope method of cross-scale γ’precipitates characterizing can play a theoretical guiding role in the parameter selection and optimization of the practical process,and has practical significance.