Atomic size effect of alloying elements on the formation, evolution and strengthening of gamma'-Ni3Al precipitates in Ni-based superalloys

2019-06-01
Eriş, Rasim
Akdeniz, Mahmut Vedat
Mehrabov, Amdulla
Show full item record
Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.
236
views
0
downloads
Mechanical properties of Ni-based superalloys strongly depend on phase and site preferences of alloying elements which influence bonding strength within gamma'-Ni3Al precipitates and microstructural characteristics of these unique class of materials. In the current work, therefore, besides disclosure of the phase partitioning behaviours of alloying X elements (i.e. X = Co, Cr, Nb, Ta or Ti) among gamma' and gamma phases, their site occupancy tendencies in gamma' precipitates (determined via first-principles ab initio calculations at 0 K) and effects on the microstructural evolution of Ni80Al15X5 alloy systems (exposed to aging at 800 degrees C for 4, 16, 64 and 256 h, respectively) have been examined. Bonding features of Ni-Al, Ni-X and Al-X atomic pairs within Ni3Al-X intermetallics have been simulated by utilizing charge density difference (CDD) method, which reveals site preferences of alloying X elements as well. Present theoretical and experimental investigations have shown that mechanical strength of Nibased superalloys is predominantly affected by bonding properties within precipitates. As atomic radii of alloying X elements become closer to that of Al atom, energy change parameter, E-Ni -> Al(X) values decrease and more Al sublattice sites are preferentially occupied in gamma' precipitates. Correspondingly, bonding strength of Ni-X atomic pairs along < 110 > directions of Ni3Al-X phases and micro-hardness properties of both as-cast and pre aged Ni80Al15X5 alloy systems enhance in the order of X = Co < Cr < Ti < Nb < Ta additions. Nevertheless, with increasing aging time, mechanical strength of alloys weakens in parallel with increasing size of gamma' precipitates simultaneously evolved from near-spherical to irregular forms.
Nickel alloys, Intermetallics, First principles, Casting methods, Phase transformation, Hardness
https://hdl.handle.net/11511/33117
Test and Measurement Center In advanced Technologies (MERKEZ LABORATUVARI), Article

Suggestions

Magnetic monitoring approach to kinetics of phase transformations in multicomponent alloy systems
Duman, Nagehan; Mekhrabov, O. Mekhrabov; Akdeniz, Mahmut Vedat; Department of Metallurgical and Materials Engineering (2012)
It is of great importance for a materials scientist both from fundamental and applicability aspects to have better understanding of solid-state phase transformations and its kinetics responsible for micro-/nano-structure development in alloys and corresponding physical and mechanical properties. Transformation kinetics can be analyzed by various experimental techniques such as thermal analysis, laborious electron microscopy combined with extensive image analysis or by measuring changes in electrical resisti...
Molecular dynamics study of random and ordered metals and metal alloys
Kart, Hasan Hüseyin; Tomak, Mehmet; Department of Physics (2004)
The solid, liquid, and solidification properties of Pd, Ag pure metals and especially PdxAg1-x alloys are studied by using the molecular dynamics simulation. The effects of temperature and concentration on the physical properties of PdxÞAg1-x are analyzed. Sutton-Chen (SC) and Quantum Sutton-Chen (Q-SC) many-body potentials are used as interatomic interactions which enable one to investigate the thermodynamic, static, and dynamical properties of transition metals. The simulation results such as cohesive ene...
Electronic properties of transition metal oxides
Mete, Ersen; Ellialtıoğlu, Süleyman Şinasi; Department of Physics (2003)
Transition metal oxides constitute a large class of materials with variety of very interesting properties and important technological utility. A subset with perovskite structure has been the subject matter of the current theoretical investigation with an emphasis on their electronic and structural behavior. An analytical and a computational method are used to calculate physical entities like lattice parameters, bulk moduli, band structures, density of electronic states and charge density distributions for v...
Magnetic monitoring approach to nanocrystallization kinetics in Fe-based bulk amorphous alloy
Duman, Nagehan; Akdeniz, Mahmut Vedat; Mehrabov, Amdulla (2013-12-01)
Much of the recent metallic glass research is devoted to controlling the crystallization of amorphous precursors with the purpose of obtaining amorphous matrix nanocrystalline alloys which combine unmatched soft magnetic properties with good mechanical properties. Therefore, it is crucial to have better understanding of crystallization mechanisms and thermal dependence of nanocrystals that are formed by annealing. This study deals with the nanociystallization kinetics of Cu-modified Fe-Co-Ni-B-Si-Nb bulk am...
Atomic ordering characteristics of Ni3Al intermetallics with substitutional ternary additions
Mehrabov, Amdulla; Akdeniz, Mahmut Vedat (1997-03-01)
The effects of substitutional ternary additions of Me = Zn, Ti, Si, Cr, Mn, Mo, W, Nb, Ta, V, Hf, or Zr on the energetical and structural characteristics of atomic short-range ordering (SRO) of Ni-3(Al(1-x)Me(x)) intermetallics with L1(2) type ordered structure have been analysed by combining the statistical theory of ordering with the electronic theory of alloys in pseudopotential approximation. The partial ordering energies and pairwise SRO parameters were calculated by taking into account the influence o...
Citation Formats
R. Eriş, M. V. Akdeniz, and A. Mehrabov, “Atomic size effect of alloying elements on the formation, evolution and strengthening of gamma’-Ni3Al precipitates in Ni-based superalloys,” INTERMETALLICS, pp. 37–47, 2019, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/33117.
METU IIS - Integrated Information Service open@metu.edu.tr