Materials for High Temperature Applications: Next Generation Superalloys and Beyond: Refractory Alloys: Processing and Properties of Novel Materials
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
Wednesday 2:00 PM
March 17, 2021
Room: RM 8
Location: TMS2021 Virtual
Session Chair: Eric Lass, University of Tennessee-Knoxville; Jeremy Rame, Naarea
2:00 PM Invited
High-temperature, Thermally-cyclable, Reaction-formed, Co-continuous Refractory Metal/Ceramic Composites for Extreme Environments: Kenneth Sandhage1; Yujie Wang1; Priyatham Tumurugoti1; Camilla McCormack1; Alex Strayer1; Adam Caldwell1; Gregory Scofield1; Zhenhui Chen1; Raheleh Rahimi1; Thuan Nguyen1; Saeed Bagherzadeh1; Kevin Trumble1; Michael Sangid1; Grigorios Itskos1; Mario Caccia1; 1Purdue University
Ultra-high-melting, co-continuous, refractory metal/ceramic composites can provide unique and attractive properties for use in extreme environments. In this talk, the processing, microstructure, and properties of reaction-formed ZrC/W (Tsolidus = 2800oC) and related refractory-metal-bearing composites will be discussed. An interconnected W phase in ZrC/W composites provides enhanced thermal conductivity and toughness at high temperatures (relative to monolithic ZrC), whereas interconnected ZrC enhances the stiffness and resistance to erosion and creep (relative to monolithic W). The similar thermal expansion of both phases also provides excellent resistance to thermal shock/cycling. ZrC/W composites have been produced in complex, near-net shapes via reactive melt infiltration of readily-formed porous WC bodies. Exposure of such shaped porous bodies to a Zr-bearing liquid results in pressureless melt infiltration and reactive conversion into fully-dense ZrC/W bodies with <1% changes in external dimensions. The application of ZrC/W and other refractory-metal-bearing composites for aerospace and renewable energy production will be discussed.
2:30 PM
ICME-guided Design of Novel Metal Matrix Composites for Extreme Environments: David Linder1; Martin Walbruehl1; Qiaofu Zhang2; 1QuesTek Europe AB; 2QuesTek Innovations
Materials modelling plays an increasingly important role in accelerating the development of novel metal matrix composites for various applications in extreme environments. Predicting the influence of processing parameters and material chemistry on the composite properties using ICME (Integrated Computational Materials Engineering) tools allows for composite design that achieve better trade-off between conflicting properties while reducing the need for costly and time-consuming experimental studies. Improvement of composite properties by substituting conventional matrix materials by high entropy alloys has recently been demonstrated with cemented carbides for friction stir welding, highlighting the potential of utilizing novel alloying concepts for MMC design. Here we present the current status of a hollistic ICME framework combining thermodynamic, kinetic and physics-based material models, which not only allows for further improvement of existing materials for well-established applications but also enables rapid exploration and design of other types of MMCs for a wider range of applications than presently used.
2:50 PM Invited
Advanced Refractory Alloys for Use at Temperatures above 1273K: Oleg Senkov1; Satish Rao1; Todd Butler1; Tinuade Daboiku1; Eric Payton1; 1Air Force Research Laboratory
New Nb-Mo-Zr based refractory alloys will be reported. These alloys have been developed to replace heavy, expensive and difficult to process commercial Nb alloys, such as C-3009, for use at temperatures up to 1873K. The density of the alloys is in the range from 7.6 to 8.6 g/cc. The alloys have a BCC matrix phase, and they also contain small amounts of secondary phases, which are rich in Zr and have BCC, FCC, hexagonal or monoclinic crystal structures depending on the concentration of other alloying elements, including oxygen and nitrogen. In the temperature range from 298K to 1873K, the alloys are ductile and have higher specific strength than C-3009. The strengthening mechanisms responsible for the observed temperature dependence of the yield stress of the alloys will be discussed.
3:20 PM
Oxidation-resistant, Thermally-cyclable, Robust Oxide/Metal Composite Materials for Concentrated Solar Power: Camilla McCormack1; Mario Caccia1; Thuan Dinh Nguyen1; Gregory Scofield1; Grigorios Itskos1; Michael Sangid; Kenneth Sandhage1; 1Purdue University
The production of electricity in a concentrated solar power (CSP) plant involves the use of heat, generated from concentrated sunlight, to expand a high-pressure working fluid so as to drive a turbine. A key step for a reduction in the cost of CSP-derived electricity would be to increase the temperature of the working fluid entering into the turbine to >750oC. Unfortunately, compact heat exchangers (HEXs) used to efficiently transfer heat to the high-pressure working fluid have been limited to temperatures <550oC, owing to a dramatic reduction in the mechanical behavior of conventional metal alloys (such as stainless steels) at significantly higher temperatures at high pressures. Ceramic/metal composites (cermets) can provide a highly-attractive combination of high-temperature properties for such compact heat exchangers. In this talk, the use of Al2O3/Cr cermets as alternative HEX materials will be discussed. Al2O3/Cr cermets are stiff, possess relatively high failure strengths, and are thermally cyclable (owing to similar thermal expansions of Al2O3 and Cr). The high-temperature oxidation resistance of Al2O3/Cr cermets will also be demonstrated in flowing CO2(g) and in synthetic air.
3:40 PM
Hot Isostatic Pressing of Niobium-based Refractory Alloy Powders: Calvin Mikler1; Brian Welk1; Benjamin Georgin1; Todd Butler2; Noah Philips3; Hamish Fraser1; 1The Ohio State University; 2Air Force Research Laboratory; 3ATI Specialty Alloys and Components
Niobium-based WC-3009 (Nb-30Hf-9W wt%) is a single-phase bcc refractory alloy designed as a candidate replacement for the still commonly utilized C-103 (Nb-10Hf-1Ti wt%) alloy. While WC-3009 exhibits superior high-temperature mechanical properties compared with C-103, fabrication is economically prohibitive, and the alloy has not been employed in any capacity. In this study, pre-alloyed HDH WC-3009 and PREP C-103 powders were canned and subsequently consolidated via hot isostatic pressing (HIP). This effort was performed to identify key alloy attributes that drive processability through HIP such that higher strength Nb-based refractory alloys can be utilized. Backscattered electron (BSE) imaging and electron backscattered diffraction (EBSD) analysis revealed the degree of recrystallization and recovery substructure formation. Transmission electron microscopy (TEM) coupled with x-ray energy dispersive spectroscopy (XEDS) were employed to analyze second phase precipitation behavior and dislocation substructures. The results indicated that hot isostatic pressing is a viable method of processing high-performance Nb-based refractory alloys.
4:00 PM
A Review of Plastic Flow and Microstructure Evolution at Elevated-temperatures in Unalloyed Niobium: Emily Brady1; Eric Taleff1; 1University of Texas at Austin
Plastic deformation and microstructure evolution in low-impurity niobium sheet materials at elevated temperatures are investigated. Uniaxial tension tests at 10-4 s-1 and faster at temperatures from 1200 to 1500℃ are used to measure flow stresses and evaluate dynamic grain growth behaviors. Grain sizes and shapes are characterized after static annealing (static case) and after tensile testing (dynamic case). Flow behaviors and microstructures of niobium sheet materials are compared with historical data from the literature. The data produced are used to determine the creep mechanism active in low-impurity niobium and gain insight into microstructure evolution during deformation.
4:20 PM
Effect of Alloy Composition on the Microstructure of Developmental Iridium Alloys: Noah Kohlhorst1; Glenn Romanoski2; Govindarajan Muralidharan2; Roger Miller2; Ji-Cheng Zhao3; 1Ohio State Univerity; 2Oak Ridge National Laboratory (ORNL); 3University of Maryland, Department of Materials Science and Engineering
Iridium alloys such as DOP-26 contain thorium which acts as a grain boundary strengthener and restricts grain growth through the formation of intermetallic precipitates. Previous work showed that cerium can be used as a partial or full substitute of thorium with a similar effect on microstructure, but minimal work was done to quantitatively compare the microstructures of alloys containing cerium. In this work, we will evaluate quantitatively the effect of cerium on the grain size, grain shape, nature and distribution of the recipitates and compare the microstructure of cerium containing alloys with the microstructure of thorium containing alloys. *Research sponsored by the United States Department of Energy (DOE) Office of Facilities Management (NE-31) at the Oak Ridge National Laboratory, managed by UT-Battelle, LLC for the U.S. DOE. Support and guidance were provided by Mary McCune of the US DOE. Primary funding was provided by the NASA Science Mission Directorate.
4:40 PM
Kinetics of Grain Boundary Segregation in an Ir Alloy*: Dean Pierce1; Govindarajan Muralidharan1; Jon Poplawsky1; George Ulrich1; 1Oak Ridge National Laboratory
Iridium (Ir) alloy DOP-26 (Ir-0.3W-0.006Th-0.005Al wt.%) is used as a fuel cladding material in radioisotope thermoelectric generators for space applications owing in part to its excellent high temperature impact ductility. Previous work has shown that additions of 20 to 1500 wppm of silicon (Si) to DOP-26 resulted in grain boundary Si concentrations of up to ~60 times bulk levels, contributing to loss of impact ductility. The focus of the present work is to understand the effect of temperature and time on the co-segregation behavior of both Si and Th to grain boundaries in Ir-alloys. Auger Electron Spectroscopy on in-situ fractured specimens and atom probe tomography was used to characterize grain boundary segregation. Effects of composition and temperature on the observed kinetics of segregation to grain boundaries will be discussed.