Advances in Multi-Principal Elements Alloys X: Alloy Development and Properties: Additive Manufacturing and Other Techniques
Sponsored by: TMS Functional Materials Division, TMS Structural Materials Division, TMS: Alloy Phases Committee, TMS: Mechanical Behavior of Materials Committee
Program Organizers: Peter Liaw, University of Tennessee; Michael Gao, National Energy Technology Laboratory; E-Wen Huang, National Chiao Tung University; Jennifer Carter, Case Western Reserve University; Srivatsan Tirumalai; Xie Xie, FCA US LLC; Gongyao Wang, Globus Medical

Thursday 2:00 PM
March 3, 2022
Room: 251A
Location: Anaheim Convention Center

Session Chair: Wen Chen, University of Massachusetts-Amherst; Duckbong Kim, Tennessee Technological University

2:00 PM
Nanostructured Oxide-dispersion-strengthened CoCrFeMnNi High Entropy Alloys: Processing, Microstructures, and Thermal Stability: Xiang Zhang¹; Fei Wang¹; Xueliang Yan¹; Xing-Zhong Li¹; Khalid Hattar²; Bai Cui¹; ¹University of Nebraska-Lincoln; ²Sandia National Laboratories
    A nanostructured oxide-dispersion-strengthened (ODS) CoCrFeMnNi high-entropy alloy (HEA) has been synthesized by a powder metallurgy process. The thermal stability, including the grain size and crystal structure of the HEA matrix and oxide dispersions, was carefully investigated by X-ray diffraction and electron microscopy characterizations after annealing at 900 şC. The limited grain growth may be attributed to Zener pinning of yttria dispersions that impede the grain boundary mobility and diffusivity. The high hardness was caused by both the fine grain size and yttria dispersions, which was also retained after annealing at 900 şC. This research implies that the combination of ODS and HEA concepts may provide a new design strategy for the development of thermally stable nanostructured alloys for extreme environments.

2:20 PM
Experimental Investigations of an Additively Manufactured Multi-principal Element Alloy with Extraordinarily High Strength: Morgan Jones¹; Jonathan Pegues¹; Michael Melia¹; Ping Lu¹; Frank DelRio¹; Raymond Puckett¹; Iver Anderson²; Emma White²; Duane Johnson²; Prashant Singh²; Andrew Kustas¹; Irene Beyerlein³; ¹Sandia National Laboratories; ²Ames Laboratory; ³University of California Santa Barbara
    Multi-principal element alloys (MPEAs) are, in general, noted for their superior mechanical properties. Their remarkable phase stability, insensitivity to thermal history, and dependence on solution strengthening mechanisms, in sharp contrast to conventional alloys like steels, makes them ideally suited for processing via additive manufacturing (AM). In sectors such as aerospace, automotive, and power generation, a great deal of effort is dedicated to developing high-performance alloys that can withstand increasingly harsh operating conditions. Surface-based deformation techniques were performed on an AM AlMoNbTaTiZr specimen to rapidly elucidate mechanical properties such as hardness, toughness, and strain rate sensitivity. Characterization of both as-deposited and deformed microstructure was performed using transmission-electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDX). We present results of experimental testing and characterization and make comparisons to reported properties of other MPEAs from literature. We show that this MPEA possesses one of the highest reported strength to weight ratios of any alloy.

2:40 PM
Additive Manufacturing and Mechanical Properties of Al18Co30Cr10Fe10Ni32 Eutectic Multi-principal Elements Alloy Fabricated by Laser-powder Bed Fusion: Abhishek Mehta¹; Thinh Huynh¹; Kevin Graydon¹; Asif Mahmud¹; Yongho Sohn¹; ¹University of Central Florida
    Additive manufacturing of novel Al18Co30Cr10Fe10Ni32 eutectic multi-principal elements alloys (MPEAs) was carried out by the laser powder bed fusion (LPBF) using gas atomized alloy powders. LPBF optimization was performed as a function of laser power (200 – 350 W) and scan speed (300 – 1800 mm/s). Density of greater than 99.6% was obtained at an optimum LPBF parameter. Microstructure of as-fabricated LPBF specimens exhibited a unique trimodal microstructure, along the build direction, which consisted fine cellular, coarse cellular eutectic structure, in addition to, conventional lamellar eutectic structure consisting of FCC and BCC phases. This microstructural variation was significantly different from the starting powder microstructure and the melt-pool microstructure observed during single laser scanning of arc-melted bulk alloy. Details of microstructural characteristics, examined via electron microscopy and X-ray diffraction, and mechanical properties (tensile and instrumented hardness) will be presented and discussed with respect to the MPEA produced by traditional manufacturing method.

3:00 PM
Mapping Processibility in the Family of Additive Manufacturing for MPEAs: Praveen Sreeramagiri¹; Hengrui Zhang²; Wei Chen²; Ganesh Balasubramanian¹; ¹Lehigh University; ²Northwestern University
    The family of metal additive manufacturing encompasses various processes viz., laser metal deposition (LMD), powder bed fusion (PBF), etc., with unique requirements in terms of materials/processing conditions. However, the transition between processes, i.e., determining the processing conditions needed to reproduce a metal with similar properties on another machine (or using another process), is not straightforward. We propose a model, to help map the process variables between machines/processes. We begin with utilizing the machine constants such as beam diameter and the material dependent energy densities to roughly bridge the process parameters between two processes. Based on a few experiments, our model further calibrates the parameter spaces between processes using statistical analyses. We employ this model to predict the parameter space for laser PBF and validate our results using AlxCoCrFeNi MPEA as a test bed.

3:20 PM
Oxidation Characteristic of Complex Concentrated Alloys FeAlCrV and FeAlCrMo: Eliska Jaca¹; Peter Minárik¹; Josef Pešička¹; Stanislav Daniš¹; Adam Hotař²; ¹Charles University; ²Technical University of Liberec
    Complex concentrated alloys (CCA) represent a new interesting class of metallic materials as some of the CCAs exhibit remarkable properties. In this study, two alloys have been investigated - FeAlCrV and FeAlCrMo, with equiatomic composition. Excellent high-temperature mechanical properties of both alloys were already reported, but potential risks associated with high-temperature oxidation and/or electrochemical oxidation are still unknown. For this reason, this study is primarily focused on this issue. Room temperature corrosion resistance measurement was performed via a potentiodynamic test in 3.5% NaCl and 0.5 M H2SO4 solution. The results showed that both alloys have excellent corrosion resistance, especially in comparison with AISI 304 alloy. High-temperature oxidation tests were performed at four temperatures (600 °C – 800 °C). The results showed that the investigated alloys exhibit poor oxidation resistance at elevated temperatures. Further characterization of the formed oxide scales was performed by XRD and SEM and compared with the theoretical model.