A5040317871- High Temperature Alloys and Creep
- Advanced Materials Characterization Techniques
- Intermetallics and Advanced Alloy Properties
- High-Temperature Coating Behaviors
- Nuclear Materials and Properties
- Metallurgical Processes and Thermodynamics
- Microstructure and mechanical properties
- Chemical Looping and Thermochemical Processes
- Fatigue and fracture mechanics
- Aluminum Alloy Microstructure Properties
- Metallurgy and Material Forming
- Iron and Steelmaking Processes
- Probabilistic and Robust Engineering Design
- High Entropy Alloys Studies
- Thermochemical Biomass Conversion Processes
- Microstructure and Mechanical Properties of Steels
Friedrich-Alexander-Universität Erlangen-Nürnberg
2016-2023
Materials Science & Engineering
2021
Abstract The creep strength of single-crystalline Co-based superalloys was found to be comparable first-generation Ni-base superalloys. However, considerable shearing the γ ′ precipitates observed in early stages. To determine strengthening contribution Ta-containing ′-Co 3 (Al,W) precipitates, several Co-Al-W-Ta determined as a function volume fraction at 1223 K (950 °C) and stress levels between 25 600 MPa. Employing Lagneborg–Bergman–Reppich (LBR) approach, it is that increases...
The anomalous yielding behavior known from Ni3Al or Ni-base superalloys is explained by the formation of immobile dislocation configurations via cross-slip leading superpartial anti-phase boundary-coupled pairs. A systematic investigation a single-crystalline Co-11Ti-15Cr superalloy transmission electron microscopy revealed absence similar sessile during initial stage. Shearing γ' precipitates superlattice stacking fault dominant deformation mechanism at peak temperature. Furthermore, high...
Compositionally complex polycrystalline γ/γ′ CoNi-base superalloys, such as CoWAlloy2 (Co41-Ni32-Cr12-Al9-W5-Ti0.3-Ta0.2-Si0.4-Hf0.1-C-B-Zr) are interesting candidates for new high-temperature materials. To maximize their strength, the microstructure has to be optimized by adjusting multi-step heat treatments. Various microstructures after different treatments were analyzed scanning and transmission electron microscopy especially in-situ small-angle neutron scattering during treatment...
Tailoring the partitioning behavior of solid solution strengtheners is a crucial design strategy for advanced Ni-based superalloys. The goal this study was to maximize enrichment Mo, Re, Ru and W in γ-matrix phase. To determine composition dependency behavior, set polycrystalline superalloys with varying contents these solution-strengthening elements W-containing single-crystalline alloy series concentrations γ′-forming Ta Ti produced. Assessed properties include phase compositions by...
Abstract The γ′ volume fraction is a key parameter in precipitation-strengthened Co- and Ni-base superalloys mainly determines the alloys’ properties. However, systematic studies with varying fractions are rare influence on thermal expansion has not been studied detail. Therefore, series of six Ta-containing Co-based alloys was designed compositions γ – tie-line, where changes systematically. During solidification, Laves (C14-type) µ (D8 5 -type) phases formed high levels W Ta. Single-phase...
The Ni content is a crucial factor for the development of γ′-strengthened Co-based superalloys and some studies have systematically addressed its influence on various properties in model superalloys. In this paper, we report first time Co/Ni ratio more advanced nine-component superalloy ERBOCo-1: exchanging Co Co/Ni-based while keeping other alloying elements constants has big variety material properties. elemental segregation after casting slightly pronounced alloy with higher Ni-content....
Co-base superalloys are considered as promising high temperature materials besides the well-established Ni-base superalloys. However, Ni appears to be an indispensable alloying element also in To address influence of base elements on deformation behaviour, high-temperature compressive creep experiments were performed a single crystal alloy series that was designed exhibit varying Co/Ni ratio and constant Al, W Cr content. Creep tests at 900 °C 250 MPa resulting microstructures defect...
The defect evolution associated with an anomalous work hardening behavior of a single crystalline quaternary Co-Al-W-Ta superalloy at 950 °C was investigated by transmission electron microscopy. As plastic deformation is initially confined to the γ matrix channels, plateau arises in stress-strain curve after yielding. At about 1% strain, extensive shearing γ′ precipitates under superlattice stacking fault formation occurs leading extreme rates up 12 GPa and total increase stress 200 MPa....
Understanding the influence of γ′ and secondary-phase fractions on mechanical properties superalloys is very important to optimize these high-strength materials. So far, this has not been systematically investigated for novel class Co-based superalloys. In study, a Co–Al–W–Ta model alloy series was designed with compositions γ/γ′ tie-line an increasing volume fraction up 70% after heat treatment at 900 °C, while few alloys are unexpectedly out two-phase region additional secondary phase 15%....
Abstract Numerical methods can accelerate the design of alloys with improved material properties. One approach is coupling multi-criteria optimization CALPHAD-based models alloy While this technique has already yielded promising new Nickel-base superalloys, applicability to CoNi-base not yet been investigated. These show properties for application as wrought high-temperature materials. We designed three which were optimized either high strength or chemical homogeneity. The cast, and...
Abstract The high volume of data resulting from a rapidly increasing number experiments in materials science necessitates an efficient preparing the before any analysis. In addition, due to large datasets some experiments, it is essential reduce sample small representative points. this study, three statistical methods for change-point analysis are tested automated selection creep which provides possibilities speed up preparation their further Moreover, approach aids practitioner produce...