Materials for High Temperature Applications: Next Generation Superalloys and Beyond: Superalloys and Beyond: Oxidation and Mechanical Behavior II
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

Thursday 2:00 PM
March 18, 2021
Room: RM 8
Location: TMS2021 Virtual

Session Chair: Mario Bochiechio, Pratt & Whitney; Martin Heilmaier, KIT Karlsruhe


2:00 PM  Invited
Understanding the Oxidation Mechanisms of Complex Concentrated Refractory-based Alloys: Todd Butler1; Tinuade Daboiku1; Joshua Gild1; Oleg Senkov1; 1Wright Patterson Air Force Base
    Refractory Complex concentrated alloys (RCCAs), which also include refractory high-entropy alloys, are an innovative class of materials that exhibit great potential for future use in high temperature, structural applications. Their compositional complexity has been reported to provide a unique landscape for the design of alloys with a variety of superior properties. In particular, the high concentration of alloying elements in RCCAs enables inherent oxidation resistance that is not readily accessible in conventional, dilute refractory alloys. This talk outlines recent developments regarding our understanding of the oxidation mechanisms in these systems and reviews particular strategies being explored in the community. RCCA oxidation mechanisms are discussed relative to classic oxidation theory and existing predictive models. Current knowledge gaps and critical future design considerations are also addressed.

2:30 PM  Invited
Effect of Al Addition on the Oxidation Behavior of a Mo-Si-B Alloy: John Perepezko1; Longfei Lu1; 1University of Wisconsin-Madison
     Among the several potential candidates for a new generation of ultrahigh temperature structural materials, Mo-Si-B alloys have drawn much attention due to their high melting point and high temperature strength. In the Mo-Si-B system, nearly all the research has focused on the Mo-rich corner, especially the Moss+Mo5SiB2 (T2) + Mo3Si three phase region. Recently, a series of Mo-Si-B alloys was designed in the Moss+T2 (Mo5SiB2)+Mo2B three phase region to examine the effect of the lower Si solubility limit in the Moss phase on the microstructure, hardness and oxidation behavior. The results showed that Mo-Si-B alloys in the Moss+T2 (Mo5SiB2)+Mo2B three phase region have higher fracture toughness and same level oxidation resistance as the Moss+T2 + Mo3Si alloys In the present study, oxidation of Mo-Si-B alloys at different Al addition levels was examined at 1100, 1200, and 1300°C. Under both isothermal oxidation and cyclic exposure the oxidation resistance was enhanced considerably.

3:00 PM  
Oxidation Behavior of Nb-Si Based Ultrahigh Temperature Alloy at 600-1350℃: Xiping Guo1; Xiaoyu Luo1; Yanqiang Qiao1; Ping Guan1; 1Northwestern Polytechnical University
    Nb-Si based ultrahigh temperature alloys are expected to be used in the temperature range of 1200~1400 °C. After alloying with Ti, Hf, Zr, Cr, Al, the oxidation resistance of Nb-Si based alloys has been significantly improved. The master alloy ingot with the composition of Nb-22Ti-15Si-5Cr-3Al-2Zr-2Hf (at. %) was prepared by vacuum non-consumable arc melting followed by high-frequency water-cooled copper crucible induction melting. The alloys were subjected to static oxidation experiments at 600, 800, 1050, 1250 and 1350 ° C for 5, 10, 20, 50, and 100 hours respectively. The thickness of the scale and the weight gains per unit area were measured, and the oxidation kinetic curves of the alloy at different temperatures were plotted. The structure, phase constituents, composition distribution, and microstructure of the scale and internal oxidation zone of the specimens have been revealed. The oxidation behavior of Nb-Si based ultrahigh temperature alloys at different temperatures was elucidated.

3:20 PM  
Oxidation of TiAl Alloys GE 4822 and TNM-B1 between 600°C and 900°C and Impact on Mechanical Properties: Mathias Galetz1; Lukas Mengis1; Anke Ulrich1; 1DECHEMA-Forschungsinstitut
    Light weight material titanium aluminides (TiAl) can substitute Ni-alloys in several parts of today´s aero engines. Their maximal service temperature is usually given in the range of 700-750 °C, because among others above their oxidation resistance becomes insufficient. Many studies have investigated the oxidation behavior of TiAl at very high temperatures, and thus well above the actual service temperature. A comparative study on the isothermal oxidation behavior of the two β–containing titanium aluminide alloys GE 4822 and TNM-B1 in the HIPed condition was carried out between 600°C and 900°C for up to 1000 h in air. Both suffer from an undesirable embrittlement due to oxidation and phase transformations in the subsurface Zone, that have a strong impact on the mechanical properties at room temperature. An approach is presented to describe phenomena that are linked to the oxidation induced embrittlement in due consideration of the already existing theories in literature.

3:40 PM  
On the High-temperature Air Oxidation Behavior of Ti3Al0.6Ga0.4C2 MAX Phase Solid-solution in the 1000 to 1300 °C Temperature Range: Tarek Ali1; Enrica Epifano2; Maxim Sokol1; Michel Barsoum1; 1Drexel University, Department of Materials Science & Engineering, Philadelphia, PA, USA; 2Laboratoire d’Etudes des Microstructures, CNRS-ONERA, Boite Postale 72, 92322 Châtillon Cedex, France
    The MAX phases, Ti2AlC and Ti3AlC2, are atomically layered ternary transition metal carbides that display damage tolerance, oxidation resistance and crack-healing behavior at high temperatures. They are recognized as alumina Al2O3 formers upon oxidation in the 1000-1200°C temperature range. However, the challenge of TiO2 formation and consequent transformation into a non-protective Al2TiO5 film at higher temperatures, has encouraged further research. In this work, bulk dense predominantly single phase Ti3Al1-xGaxC2 (x ≈ 0.4) quaternary solid-solution MAX phase was hot-pressed and its isothermal oxidation was explored in ambient air, at 1000-1300°C, for 15-300 h. At 1000°C, dense adherent alumina scale forms, with superior oxidation resistance compared to Ti3AlC2 and even Ti2AlC. At 1200°C, the scale becomes coarser with oxidation resistance approaching that of Ti3AlC2 ternary. At 1300°C, alumina scale wrinkling is observed, affecting overall integrity of the oxide scale. Moreover, nucleation of anisotropic Al2TiO5 leads to formation of underlying pores and microcracks.