Influence of rhenium and ruthenium on the local mechanical properties of the γ and γ′ phases in nickel-base superalloys

Abstract

The effect of rhenium and ruthenium on the hardness of the γ' precipitates and the γ matrix in nickel-base superalloys was investigated using a nanoindenting atomic force microscope. The partitioning behaviour of the alloying elements and the lattice misfit between the γ and γ' phase were determined in fully homogenised samples to explain the alloying effects. Rhenium strongly strengthens γ as it predominantly partitions to γ and has a strong solid solution hardening effect. Ruthenium strengthens both γ and γ' due to a more homogeneous partitioning behaviour. Ruthenium was found to cause less partitioning of Rhenium to γ. This results in a stronger increase of the γ' hardness. The change of the nanoindentationderived hardness of both phases could be mainly attributed to the solid solution strengthening of Re and Ru.

Elasticity mapping of precipitates in nickel-base superalloys using atomic force acoustic microscopy

“…As the exact size and shape of the tip are not known, the measurement on a reference minimizes the error involved in calculating the indentation modulus on the unknown sample. The hardness of the silicon tip with (100) orientation is reported to be in the range of 5-10 GPa [46,50] which is similar to the hardness values reported for the matrix (*6 GPa) and c 0 precipitate (9 GPa) in nickel-base superalloys [48]. These hardness values are of the same order or slightly less than the maximum pressure expected below the tip.…”

Anomalous aging behavior of a Ni–Mo–Cr–Re alloy

“…Re was added to Ni-Co-W-Cr-Al-Ta alloys for improvement of the high temperature properties before. Research has been undertaken to understand the beneficial effects of Re [35][36][37][38][39][40] in such alloys. Earlier work indicated that Re formed clusters or segregated at the interfaces between the precipitates and the matrix.…”

Phase composition of Ni-Al-Co-Me-based superalloy modified by deformation

“…In the alloy, it is (Ni, Co) 3 (Al, Cr, Ti, Mo, Nb) [8] composition close to the stoichiometric [8]. Also, some excess (~0.5 %) of Co atoms is observed in the alloy that results in the formation of Со 3 Al phase having the DO 24 superstructure [4], which is suggested to be called as -phase.…”

“…The structural investigations of the original state of the alloy (after the directional crystallization) show that the multicomponent intermetallic -phase is the alloy base having L1 2 superstructure [1,4]. Its volume fraction is 0.78.…”

“…In real nickel-based superalloys with the multicomponent composition, atoms of such elements as Со, Ti, Cr, Mo, Nb are present along with Ni and Al atoms [2]. Alloying with the refractory elements considerably increases the operational temperature and creepresistance of superalloys [1][2][3][4]. This paper mainly focuses on the investigation of the phase and structural conditions of Ni-Al-Со-Me-based superalloy, the volume fractions and morphology of its phases in the original state.…”