Characterization of nanoscale precipitates in superalloy 718 using high resolution SEM imaging
Characterization of nanoscale precipitates in superalloy 718 using high resolution SEM imaging
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DOI：
10.1016/j.matchar.2018.12.018
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发表时间：
2019-02-01
影响因子：
4.7
通讯作者：
Carter, J.
中科院分区：
文献类型：
--
作者：
Smith, T. M.;Senanayake, N. M.;Carter, J.
目前，由于 718 超级合金中的 γ''、γ' 和 δ 析出物的尺寸、晶体结构、低体积分数和类似的化学成分，获得精确的体积分数和尺寸测量一直具有挑战性。这些测量对于验证沉淀模型是必要的，从而增强选择性激光熔化制造。高温合金 718 兼具优异的机械性能和可加工性，是选择性激光熔化制造的有前途的候选材料。一种新技术将高分辨率畸变校正 SEM 成像与高分辨率 X 射线能量色散光谱相结合，可以准确、独立地测量这三种沉淀物的尺寸、体积分数和数密度。获得选择性激光熔化高温合金 718 的样品，并对高温合金 718 进行常规热处理，在 1010 摄氏度下固溶一小时，气淬，然后进行两步时效（718 摄氏度/11 小时 -> 621 摄氏度/6 小时），以产生具有所有三种沉淀类型的微观结构。使用 X 射线衍射和相提取方法进一步验证了这些结果。
At present, obtaining accurate volume fraction and size measurements of gamma '', gamma', and delta precipitates in Superalloy 718 has been challenging due to their size, crystal structures, low volume fractions, and similar chemistries. These measurements are necessary to validate precipitation models that in turn enhance selective laser melting fabrication. Superalloy 718 is a promising candidate for selective laser melting fabrication due to a combination of excellent mechanical properties and workability. A new technique, combining high resolution distortion corrected SEM imaging and with high resolution x-ray energy dispersive spectroscopy, has been developed to accurately and independently measure the size, volume fraction, and number densities of these three precipitates. A specimen of selective laser melted superalloy 718 was obtained and underwent a conventional heat treatment for superalloy 718 where it was solutionized at 1010 degrees C for one hour, gas quenched and followed by a two-step age (718 degrees C/11 h -> 621 degrees C/6 h) in order to produce a microstructure with all three precipitate types present. These results were further validated using x-ray diffraction and phase extraction methods.