Recent Investigations and Developments of Titanium-containing High Entropy Alloys: Session I
Sponsored by: TMS Structural Materials Division, TMS: Titanium Committee
Program Organizers: Masahiko Ikeda, Kansai University; Masato Ueda, Kansai University; Carl Boehlert, Michigan State University; Peter Liaw, University of Tennessee

Wednesday 8:30 AM
March 2, 2022
Room: 251C
Location: Anaheim Convention Center

Session Chair: Masato Ueda, Kansai University; Peter Liaw, University of Tennessee; Masahiko Ikeda, Kansai University; Carl Boehlert, Michigan State University

8:30 AM  Invited
Biocompatible Titanium Containing Medium and High Entropy Alloys: Konstantinos Georgarakis1; Kimon Konakoglou1; Martin Stiehler1; Mark Jolly1; 1Cranfield University
     Using appropriate alloy design strategies and thermodynamic calculations, medium and high entropy alloys were developed with BCC structures and attractive combinations of biocompatibility, corrosion resistance, low elastic modulus, high mechanical strength and ductility. Novel non-equimolar alloys were produced by arc melt- casting in an Ar inert atmosphere from simple to more complex compositions starting on the known refractory system TiZrNbTaMo. This work focuses on the relations between chemistry, structure and properties of the developed MEAs and HEAs. Further surface modifications can be carried out to bioactivate the alloys surfaces for improved interactions between the metallic bio-materials and the human tissue. The achieved combinations of bio-compatibility, electrochemical and mechanical properties indicate that Bio-HEAs are very promising for applications as implant materials. The enormous space for further development and optimization offered by the high entropy alloying strategies cannot be underestimated.

8:50 AM  
NOW ON-DEMAND ONLY - In-situ Laser-deposited Ti-based High Entropy Alloys for Aerospace Applications: Modupeola Dada1; Patricia Popoola1; Samson Adeosun2; Ntombi Mathe2; Sisa Pityana2; Thembisile Dlamini2; Raji Sadiq3; 1Tshwane University of Technology; 2Council for Scientific and Industrial Research; 3Yaba College of Technology, Lagos Nigeria
    Contrary to the conventional method of mixing pre-alloyed powders via a ball mill prone to segregation and contamination, this study investigates the capability of designing the next generation of compositionally graded materials for aerospace components. AlCoCrFeNiTiVx High Entropy Alloys were successfully fabricated by satelliting the base AlCoCrFeNiTi alloy powder and the smaller Vanadium powder using a double powder feedstock via in-situ reactive alloying. Regulating the feed rate gave different atomic ratios of Vanadium. The microstructural and nanomechanical properties were investigated using XRD, SEM and a nanoindentation tester, respectively. The experimental results showed satelliting the parent AlCoCrFeNiTi alloy with Vanadium had a homogeneous distribution with dendritic structures. The nanomechanical properties of the alloys increased with a decrease in the powder feed rate. This study defines the capabilities of in-situ fabrication of high entropy alloys and presents novel techniques for preparing equiatomic or near-equiatomic high entropy alloys using laser additive manufacturing.

9:10 AM  Invited
Gas Tungsten Arc Welding of Cr29.7Co29.7Ni35.4Al4Ti1.2 (at.%) High Entropy Alloy: Joao Oliveira1; Francisco Coury2; 1FCT-UNL; 2UFSCAR
     In this work, a dual-phase Cr29.7Co29.7Ni35.4Al4Ti1.2 (at.%) high entropy alloy is welded for the first time. To do so, gas tungsten arc welding was used. Microstructure characterization encompassing electron microscopy and high energy synchrotron X-ray diffraction coupled with thermodynamic calculations and mechanical property assessment were used to rationalize the effect of the weld thermal cycle on the phase structure, local mechanical properties and residual stresses of these welded high entropy alloys.The ability to successfully join high entropy alloys can further expand their potential applicability for structurally-oriented applications.

9:30 AM  Invited
Evolution of Microstructure and Deformation Substructure in Al1 Mo0.5 Nb1Ta0.5Ti1Zr1, a Refractory HEA Alloy with Disordered BCC Precipitates Embedded in a Continuous Ordered B2 Matrix: G. Babu Viswanathan1; Jean-Philippe Couzinie2; Zachary Kloenne1; Brian Welk1; Oleg Senkov3; Hamish Fraser1; 1The Ohio State University; 2The Ohio State University; Université Paris Est ICMPE; 3UES Inc.
    The introduction of refractory elements in the high-entropy concept has led to the design of complex alloys with body centered cubic (BCC) microstructure with the aim to develop new materials with enhanced mechanical properties at high temperature. In particular, the ordered B2 phase in the BCC matrix has been highly sought in the case of refractory compositions with the aim to mimic the g-g’ type microstructure obtained in Ni-based superalloys. In alloy Al1 Mo0.5 Nb1Ta0.5Ti1Zr1 in this study the microstructure is however inverted compared to Ni-based superalloys with a B2 matrix and BCC precipitates embedded in it. To this end, the current study will focus on describing first the concomitant formation of fine scale microstructure leading to BCC+B2 microstructures with strong analogy to Ni-based superalloys and second, the characterization of defects in the plastic zone beneath the nano-indentation at RT.