High Temperature Creep Properties of Advanced Structural Materials: Poster Session
Sponsored by: TMS Structural Materials Division, TMS: High Temperature Alloys Committee
Program Organizers: Gianmarco Sahragard-Monfared, University of California, Davis; Mingwei Zhang, Lawrence Berkeley National Lab; Jeffery Gibeling, University of California, Davis
Monday 5:30 PM
March 20, 2023
Room: Exhibit Hall G
Location: SDCC
F-1: A Study on Microstructure and Mechanical Properties of Fe-Cr-Ni-Al-V Alloys: Kanghyun Park1; Ho-seop Song1; Jeongeun Kim1; Ka Ram Lim2; Chanho Lee3; Gian Song1; 1Kongju National University; 2Advanced Metals Division, Korea Institute of Materials Science; 3Materials Science and Technology Division, Los Alamos National Laboratory
There have been many efforts to improve creep-resistance of ferritic materials. Fe-Cr-Ni-Al alloys reinforced by coherent B2-NiAl precipitates show nearly zero lattice misfit between B2-NiAl precipitates and Fe matrix, which can improve the microstructural stability. Recently, new strategies to increase the creep-resistance have been reported, such as addition of Titanium into Fe-Cr-Ni-Al alloy, which forms hierarchical precipitate B2-NiAl/L21-Ni2TiAl. In this study, our objective is to enhance the mechanical properties at high temperatures by adding vanadium into Fe-Cr-Ni-Al alloy. Vanadium was employed to adjust the microstructures, such as size of coherent B2-NiAl precipitates. The microstructures, mechanical properties and strengthening mechanisms at 973K were examined using Transmission-electron-microscopy, X-ray diffraction, and theoretical calculation. It was found that the vanadium results in the reduction of lattice misfit between matrix and precipitates. Furthermore, hierarchical structure in the precipitate was established in V-containing alloys, which plays a crucial role in enhancing the yield strength at 973K.
F-2: Effects of Controlling Ti and Al on Microstructure and Mechanical Properties of Fe-Cr-Co-Al-Ti Ferritic Alloys: Jeongeun Kim1; Kanghyun Park1; Byungchan Cho1; Karam Lim2; Chanho lee3; Jiwoon Lee1; Gian Song1; 1Kongju National University; 2Advanced Metals Division, Korea Institute of Materials Science (KIMS); 3Materials Science and Technology Division, Los Alamos National Laboratory
Fe-Cr-Ni-Al-Ti ferritic alloys strengthened by hierarchically-structured coherent precipitates (B2-NiAl/L21-Ni2TiAl) exhibit excellent creep properties due to optimized coherent lattice strain between the Fe matrix and precipitates. However, These alloys consist of nano-scale B2-NiAl precipitates forming during cooling, which is known to deteriorate the room temperature ductility. In this study, we designed new Fe-Cr-Co-Al-Ti ferritic alloys to avoid the formation of the B2-NiAl cooling precipitate and enhance the mechanical properties at room and high temperatures. Cobalt was employed instead of Nickel to form precipitates coherent with the BCC Fe matrix, such as B2-CoTi, CoAl, and L21-Co2TiAl phases. Furthermore, the main elements to form the coherent precipitates were systematically adjusted to achieve the different volume fraction of the precipitates and optimize the lattice strain between the precipitate and matrix. We will present the microstructure and mechanical properties of newly-designed Fe-Cr-Co-Al-Ti ferritic alloys, characterized using Scanning-Electron-Microscope, Transmission-Electron-Microscope, X-ray Diffractometer, Universal Testing Machine.
F-3: Strengthening Against Creep at Elevated Temperature of HEA Alloys of the CoNiFeMnCr Type Using MC-carbides: Patrice Berthod1; 1University of Lorraine
Cast high entropy CoNiFeMnCr alloys can become alternative solutions to cast cobalt-based and nickel-based superalloys able to resist creep at 1000°C and beyond. The partial substitution of Co and Ni by Fe and Mn allow lower cost and lower dependence on the Co and Ni critical elements. However, their grain boundaries need to be strengthened.In this work equimolar CoNiFeMnCr alloys were elaborated by high frequency induction melting under inert atmosphere, after having added carbon and either Ta or Hf, in quantities rated to favor the development of an intergranular network of script-like eutectic carbides, either TaC or HfC. These carbides were successfully obtained with the required location and morphology. 3 points bending creep tests were carried out at 1100°C for an induced maximal tensile stress equal to 20 MPa. Interesting resistance was noted for some of these alloys, taking into account the high levels of applied stress and temperature.