Mathematical-Thermodynamic Prediction and Kinetics of Eta Phase Formation in Fe–Ni-Based Superalloys

این مقاله توسط مترجمان مهندسی مواد و متالوژی موسسه البرز ویرایش( ویرایش نگارشی و گرامری) شده است. این مقاله در سال 2018 در یکی از مجلات اشپرینگر به چاپ رسیده است.
نویسنده اصلی
معصومه سیف اللهی
نام مجله
Transactions of the Indian Institute of Metals
سال انتشار
2018
دانلود تصویر صفحه اول مقاله
معصومه سیف اللهی
Abstract

Time–temperature–precipitation diagram of eta phase formation was established for an Fe–Ni based superalloy by means of mathematical-thermodynamic analysis, kinetic investigation, and microstructural observation. The eta phase started to precipitate at the expense of the γ′ phase after prolonged aging. On the basis of thermodynamic prediction, the interaction between Gibbs free energy of eta phase formation and activation energy for diffusion of elements, especially titanium, was considered. The tip of TTP diagram was obtained at 817 °C, on the basis of mathematical-thermodynamic prediction, and 825–840 and 840 °C, on the basis of microstructural evolution and kinetic analysis, respectively. Kinetic investigations predicted that the eta transformation started with diffusion of Ti into Ni. This indicated that, with the progress of transformation, as n in Avrami’s equation predicts, other eta formation mechanisms such as γ′ to eta transformation, instant nucleation from the matrix, coincidence of eta lamellas, etc. increased n and activation energy


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