Study on quantitative statistical distribution characterization method for niobium-rich phase in GH4169 alloy and its application
A large amount of niobium is added into GH4169 alloy to improve the high temperature strength.Niobium segregation is inevitably generated during the preparation process,leading to the formation of many niobium-rich phases.The morphology,quantity,size and distribution of these niobium-rich phases will have a direct impact on the mechanical properties of the material,so it is necessary to conduct the quantitative original position statistical distribution characterization of niobium-rich phases.In this paper,a quantitative statistical distribution characterization method for the full range of micron niobium-rich phases in GH4169 alloy was established based on scanning electron microscope(SEM)multi-field automatic acqui-sition and energy spectrum efficient analysis technology.By setting the brightness and contrast of scanning electron microscope and optimizing the acquisition time of energy spectrum counting,the good segmenta-tion of niobium-rich particles and matrix images as well as reliable detection of micron-grade niobium-rich phases were achieved.The information of the full range of micron niobium-rich phases in the test area,in-cluding the position,morphology,size and quantity,was obtained.Moreover,the two-dimensional distribu-tion diagrams and size frequency distribution diagrams of the niobium-rich phase were drawn.The proposed method was applied to the quantitative and statistical distribution characterization of niobium-rich phases in different areas of cross sections of GH4169 alloy bars.The evolution law of quantity and size distribution of niobium-rich phases from center to edge of bars was discussed.The quantity of niobium-rich phases showed the trend of less at center and edge but more at r/2(r was the radius)position.The average size of niobi-um-rich phases at center was maximum.The average size was similar at r/2 position and edge,but it de-creased at the center.This study provided reference for the subsequent improvement process to reduce the size of niobium-rich phases.
niobium-rich phasescanning electron microscope(SEM)energy dispersive spectrometry(EDS)quantitative statistical distributionGH4169 alloysizequantity