|About this Abstract
||2020 TMS Annual Meeting & Exhibition
||High Entropy Alloys VIII
||Atom Probe Tomography Study of a Fe25Ni25Co25Ti15Al10 High-entropy Alloy
||Zhiqiang Fu, Andrew Hoffman, Benjamin MacDonald, Maalavan Arivu, Haiming Wen, Enrique Lavernia
|On-Site Speaker (Planned)
Transmission electron microscopy (TEM) and atom probe tomography (APT) were utilized to investigate the microstructure and phases in a Fe25Ni25Co25Ti15Al10 high-entropy alloy (HEA) prepared by powder metallurgy. The bulk HEA exhibits a microstructure composed of a minor bcc phase (17.7 vol.%), together with a primary fcc phase (82.3 vol.%) containing hierarchical nanoprecipitates. The bcc phase, was a B2-type NiAl phase, containing substantial amounts of Co, Ti and Fe. The fcc phase consisted of a γ Fe-(Co,Ni)-based solid-solution matrix (A1), and coherent primary γ’ (Ni,Co)3-(Ti,Al)-based intermetallic precipitates (L12). A1 structured secondary γ* precipitates were found coherently embedded within the L12-γ’ precipitates. In addition, a complex type of Al-Ti-O oxide as well as a (Ti,Ni)(C,N) was identified via APT. To validate these findings, the CALPHAD method was utilized with ThermoCalc’s newest HEA database to calculate the relative volume fraction and chemistry of possible equilibrium phases given the bulk composition and processing parameters.
||Planned: Supplemental Proceedings volume; Planned: Supplemental Proceedings volume