Materials for High Temperature Applications: Next Generation Superalloys and Beyond: Superalloys: Beyond Nickel-based Superalloys
Sponsored by: TMS Structural Materials Division, TMS: Refractory Metals Committee
Program Organizers: Govindarajan Muralidharan, Oak Ridge National Laboratory; Martin Heilmaier, KIT Karlsruhe; Benjamin Adam, Oregon State University; Mario Bochiechio, Pratt & Whitney; Katerina Christofidou, University of Sheffield; Eric Lass, University of Tennessee-Knoxville; Jeremy Rame, Naarea; Sallot Pierre, Safran; Akane Suzuki, GE Aerospace Research; Michael Titus, Purdue University
Tuesday 8:30 AM
March 16, 2021
Room: RM 8
Location: TMS2021 Virtual
Session Chair: Jeremy Rame, Naarea; Sallot Pierre, Safran
8:30 AM Invited
Accelerated Design of γ′-strengthened Co-base Superalloys with Improved Comprehensive Performances: Qiang Feng1; Longfei Li1; Wendao Li1; Min Zou1; Xiaoli Zhuang1; Ji-Cheng Zhao2; 1University of Science & Technology Beijing (USTB); 2University of Maryland
Novel γ′-strengthened Co-base alloys can provide unique solutions to the limitations of Ni-base superalloys, however, only a few of γ′-strengthened Co-base superalloys with good comprehensive performances have been reported due to the limited knowledge of alloying element effects. In our recent work, the multicomponent diffusion multiple method was used to investigate the individual and interactive effects of different alloying elements, e.g. Ni, Cr, Al, W, Ti, Ta, Mo, Nb, on the long-term microstructural stability of γ′-strengthened Co-base superalloys at the target service temperatures of single-crystal or wrought superalloy, with the help of the machine learning method which can establish the relationships between compositional variations and microstructural stabilities based on the data set of diffusion multiples. In combination with our experimental investigations, multicomponent γ′-strengthened Co-base superalloys with well balance of long-term microstructural stability, strength and oxidation resistance could be developed for different service purposes, such as turbine blades and disks.
9:00 AM
Effects of Key Elements Ni, Cr and W on High-temperature Microstructural Stability of Multicomponent Co-base Superalloys: Longfei Li1; Wendao Li1; Min Zou1; Qiang Feng1; Ji-Cheng Zhao2; 1University of Science & Technology Beijing (USTB); 2University of Maryland
Novel γ′-strengthened Co-base superalloys opens a pathway to new generation high-temperature material. The knowledge of alloying effects on the high-temperature microstructural stability is crucial for the design of multicomponent Co-base superalloys, which is still limited nowadays as the transitional method is indeed inefficient and costly. In this work, an efficient approach combining CALPHAD and diffusion-multiple was used to study the individual and interactive effects of Ni, Cr and W on the long-term microstructural stability of Co-Ni-Al-W-Ta-Ti alloy system at 1000 °C. The relationships between the compositions, microstructural characteristics and elemental partitioning coefficients were established over a large compositional range by SEM, EMPA and thermodynamic analyses, and the individual and interactive effects of Ni, Cr and W on the long-term microstructure stability of multicomponent Co-base alloys were discussed. This study will be helpful for accelerating the development of multicomponent Co-base superalloys, as well as populating the thermodynamic database.
9:20 AM Invited
Experimentally Determined Creep Properties of Various Alloys and Conclusions for Beyond Nickel-based Superalloys: Uwe Glatzel1; 1University Bayreuth
Internal stress contributions in single and multi-phase alloys will be briefly discussed. The knowledge of Ni-base superalloys of several decades show that different stress contributions (solid solution, dislocation back stress, misfit, Orowan and γ' cutting) are well understood and established. With the exception of solid solution strengthening, these effects can be estimated by theory and/or determined experimentally quite reliable. This will be exemplified by creep observations of different alloys, mainly at 980°C, but also up to 1450°C in correlations with microstructures. Conclusions of stress discussions and creep observations will be drawn for future materials beyond Ni-based superalloys. Further considerations like oxidation resistance (e.g. creep testing in air) and room temperature ductility are additionally of importance and taken into account.
9:50 AM Keynote
Metallic Materials Beyond Nickel-base Superalloys: The Challenges and Potential: Tresa Pollock1; 1University of California, Santa Barbara
Superalloys have long been desirable for critical aerospace applications, due to their balanced suite of properties. As operating temperatures have continued to rise, coatings for superalloys have played and increasingly important role. Emerging metallic systems showing promise beyond superalloys include cobalt-base alloys, refractory-based materials, multi-principal element alloys, intermetallics and combinations of these classes of materials. Advances in each class are limited by the large potential design space and the complexity of the processing paths. Design tools and approaches that address these challenges are emerging and will be discussed along with future needs in these areas. Current property challenges for each class of material will be highlighted. Finally, the benefits of additive manufacturing as an enabling path for new, higher temperature materials will be addressed.
10:30 AM
Modeling Planar Fault Energies in Ordered D022 Structures: K V Vamsi1; Tresa Pollock1; 1University of California Santa Barbara
High temperature structural materials such as superalloys are strengthened by coherent intermetallic precipitates, including γ' (L12 structure, cubic) and γ'' (D022 structure, tetragonal) embedded in a fcc matrix. These precipitates are ordered and a variety of deformation mechanisms involving creation of planar faults are reported in the precipitate shearing mechanical deformation regimes. However, due to the complex crystal structure of the γ'' and its low symmetry, the deformation mechanisms are complex in D022 containing alloys and the knowledge on planar fault energies is very limited. With growing literature in the high entropy compositions strengthened by γ'', there is a need for better understanding of the mechanisms and the underlying planar fault energies in γ''. A high-throughput diffuse multi-layer fault model is employed to investigate the proximate structures to estimate planar fault energies in D022. The new methodology and effect of alloying on fault energies in Ni3Nb will be discussed.
10:50 AM
Inverse Design of Chemistry of High Temperature Ni-base Superalloys Using CALPHAD and Machine Learning: Rajesh Jha; George Dulikravich1; 1Florida International University
Using 120 experimentally verified Nickel base superalloys we performed calculations to estimate the critical phases responsible for high temperature applications (FCC_A1 (γ) and FCC_L12 (γ’)) and one detrimental TCP phase that needs to be avoided (µ-phase). Phase stability calculations were performed at desired temperature of application to determine critical phases, followed by a set of machine learning algorithms on the data obtained from CALPHAD approach. The purpose was to find the composition range so that alloys manufactured through a similar thermal treatment protocol will have maximized critical phases responsible for high temperature properties, while minimizing the detrimental phases. We determined correlations between alloying elements and critical phases; critical phases and properties of interest, and strengthening (γ’) phase and detrimental (µ) phase. Machine learning was used to inversely determine the amount of critical phases and chemistry/composition that would yield this amount of critical phases for given stress-to-rupture and time-to-rupture values.
11:10 AM
Direct Production of Complex Metallic Alloys: Jawad Haidar1; 1Kinaltek Pty Ltd.
Results are presented for direct production of complex metallic systems based on Fe, Cr, Co, Ni, Cu, Zn, V, Nb, Mo, Sn, Sb, Ta, W, Ag and Al. The synthesis method provides for a mixture of precursor metal chlorides to be reacted exothermically with Al under conditions of controlled reaction rates and exothermic heat generation, and leading to synthesis of alloy powders in one step. Alloying additives such as C, B, Si and Ti can be included. The approach is suitable for synthesis of a large number of alloys and can be a versatile mean for developing new alloy compositions. Results are presented for synthesis of INCONEL and MONEL alloys.