Potentiodynamic study of the influence of gamma prime and eta phases on pitting corrosion of A286 superalloy

Effect of Carbon and Titanium Variations in Fe‐Based Heat‐Resistant Superalloy A286 on TiC and η Phase Formation

“…Gamma prime phases are also supposed to form in this alloy after aging, but their size is very small and unable to be seen by optical micrographs or by SEM. [6][7][8]14] Nodular TiC (fcc) and platelet η (hcp-Ni 3 Ti) phases can be seen with an optical microscope. [1,18] Titanium in the 0.00C-2.38Ti wt% alloy is found to compound with Al after aging treatment, which shows the same results as in the samples after solid solution treatment.…”

“…Typical areas of applications include aircraft engines, turbine wheels and blades, fasteners and springs, etc. [ 2–6 ] In this alloy, eta ( η ) Ni 3 Ti hcp phase is a stable phase which is formed from the dissolution of γ′ phase [ 7–9 ] at aging temperatures in the range of 600 850 °C. [ 10–13 ] Some researchers stated that during prolonged hot‐working above 720 °C, η phase can easily precipitate at grain boundaries from the fcc austenitic matrix, [ 14 ] which can have a direct influence on the creep behavior of the alloys.…”

“…As a heat-resistant superalloy, it has been designed for applications requiring sufficiently high creep fracture strength and excellent fatigue resistance at temperatures as high as 700 C. Typical areas of applications include aircraft engines, turbine wheels and blades, fasteners and springs, etc. [2][3][4][5][6] In this alloy, eta (η) Ni 3 Ti hcp phase is a stable phase which is formed from the dissolution of γ 0 phase [7][8][9] at aging temperatures in the range of 600 850 C. [10][11][12][13] Some researchers stated that during prolonged hotworking above 720 C, η phase can easily precipitate at grain boundaries from the fcc austenitic matrix, [14] which can have a direct influence on the creep behavior of the alloys. [15,16] Depending on the chemical composition and heat treatment conditions, η and carbide phases precipitate simultaneously or sequentially in this alloy system.Many efforts have been made by researchers to find a suitable composition which can enhance the strengthening mechanism by proper control of eta (η) phases up to some extent at high temperature by the addition of alloying elements.…”

Effect of Widmanstätten η phase on tensile shear strength of resistance spot welding joints of A286 superalloy

“…A286 superalloy is strengthened by the precipitation of the ordered fcc g' phase (Ni 3 (Al,Ti)), coherent with the austenite matrix [2][3][4]. The g' phase is unstable and, after a sufficiently long aging treatment at sufficiently high temperature, dissolves to form the stable hcp h phase (Ni 3 Ti) [4][5][6][7]. The h phase may precipitate at grain boundary by cellular reaction at lower aging temperatures, or into the grain with Widmanstätten morphology at higher aging temperatures [7][8][9].…”

Effect of metallurgical evolution during post-weld aging treatment on localised corrosion of resistance spot welding joints of A286 superalloy

“…The influence of precipitation hardening on the corrosion behaviour of A286 superalloy has been studied in previous works [30,31] where it was concluded that γ ′ and η precipitates may cause the passive layer that forms on them to become more unstable. On the other hand, as indicated by Martín et al [19], in the weld nugget of the RSW joint, which is formed from the solidification of the molten metal [32,33], the interdendritic region is enriched in Ni and Ti.…”