Phase Transformations and Microstructural Evolution: Aluminum Alloys
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS: Phase Transformations Committee
Program Organizers: Ashley Paz y Puente, University of Cincinnati; Mark Aindow, University of Connecticut; Sriswaroop Dasari, Idaho National Laboratory; Ramasis Goswami, Naval Research Laboratory; Megumi Kawasaki, Oregon State University; Eric Lass, University of Tennessee-Knoxville; Joshua Mueller, Michigan Technological University; Eric Payton, University of Cincinnati; Le Zhou, Marquette University

Tuesday 8:00 AM
March 21, 2023
Room: 25C
Location: SDCC

Session Chair: Ramasis Goswami, Naval Research Laboratory

8:00 AM
An Investigation of Nanomechanical Properties of Nanocrystal Embedded Marginal Metallic Glasses: Can Okuyucu¹; Doğuhan Sarıtürk¹; Mohammad Abboud²; Amir Motallebzadeh³; Sezer Özerinç¹; Ilkay Kalay⁴; Yunus Kalay¹; ¹Middle East Technical University; ²Technische Universitat Darmstadt; ³Koc University; ⁴Çankaya University
    Nanocrystalline materials have been subjected to considerable research due to the great potential of improving several material properties through grain size refinements. Among various types of nanocrystalline materials, the ones that can be produced by devitrification of metallic glass have recently taken a further interest owing to their impressive mechanical properties. However, the formation of highly localized strain during deformation causes metallic glasses to fail catastrophically after yielding. Metallic glass/nanocrystal composites, on the other hand, have shown improved ductility over monolithic glass. In this respect, we have investigated the microstructural evolution at far-from-equilibrium conditions and revealed mechanical properties of fully amorphous and partially crystalline Al-RE alloys (RE: Sm, Tb) through nanoindentation and micropillar compression. Mechanical properties have been characterized based on the nanocrystal population in melt-spun ribbons and thin-films with various nanocrystal morphologies. HRTEM analysis of the shear band propagation in nanocrystal embedded glassy matrix will be discussed in detail.

8:20 AM
Microstructural Evolution in an Aluminum-Cerium Alloy under Long Term Aging Conditions: Opemipo Adetan¹; Dinc Erdeniz¹; ¹University of Cincinnati
    Aluminum-cerium alloys have attracted the interest of the aluminum alloy community due to their excellent microstructural stability at elevated temperatures, providing strengthening via the formation of Al₁₁Ce₃ intermetallic upon eutectic solidification. The addition of erbium, scandium, and zirconium has further improved the ambient and elevated-temperature mechanical properties. This investigation focuses on the long-term microstructural evolution of an Al-Ce-Er-Sc-Zr alloy, with an emphasis on the two strengthening phases, Al₁₁Ce₃ and L1₂-ordered Al₃(Er, Sc, Zr). Isothermal aging treatments for up to 3000 hours are conducted to evaluate the evolution of these two phases, using microhardness tests, optical and electron microscopy, and X-ray diffraction studies. High-temperature tensile tests and creep experiments are performed to reveal the effect of these heat treatments on the thermo-mechanical performance of the alloy and to further investigate microstructural evolution under simulated service conditions. CALPHAD modeling is employed to aid our understanding of this alloy with promising elevated-temperature properties.

8:40 AM
Effect of Mn on Eutectic Phase Equilibria in Al-rich Al-Ce-Ni alloys: Alice Perrin¹; Ying Yang¹; Richard Michi²; Kevin Sisco³; Alex Plotkowski¹; Amit Shyam¹; ¹Oak Ridge National Lab; ²Owens Corning; ³University of Tennessee
    The phases and microstructure of cast samples of Al-Ce-Ni and Al-Ce-Ni-Mn alloys were characterized for several annealing conditions which revealed the equilibrium phases at different temperatures. Phase analysis confirmed that minute levels of Mn substituted for Ni in the system drastically shifts the liquidus projection in the Al-rich corner of the ternary phase diagram such that the eutectic Al3Ni phase is suppressed entirely in favor of the Al23Ni6(Ce,Mn)4 phase. This data was combined with CALPHAD modelling of the liquidus projection for the quaternary system Al-Ce-Ni-Mn. Phase analysis of a heat treated AM sample of Al-Ce-Ni containing small amounts of Mn confirmed that the equilibrium phases present are consistent with cast samples. This result demonstrates the vast potential for using minute levels of alloying element Mn to drastically alter phase stability and microstructure in Al-Ce-Ni systems.

9:00 AM
The Effect of Thermomagnetic Processing on the Properties and Microstructure of Aluminum and Ferrous Alloys: Michael Kesler¹; Michael Thompson²; Hunter Henderson³; David Weiss⁴; Zachary Tener¹; Ramon Padin-Monroig⁵; Megan Hurley⁵; Steven Flynn⁵; Bart Murphy¹; Orlando Rios²; Gerard Ludtka⁵; Aurelien Perron³; Victoria Miller⁵; Michael Tonks⁵; Michele Manuel⁵; ¹Oak Ridge National Laboratory; ²University of Tennessee; ³Lawrance Livermore National Lab; ⁴Eck Industries; ⁵University of Florida
     This research explored the effect of induction-coupled thermomagnetic processing on the solution and aging treatments in aluminum and ferrous alloys. The applied magnetic field hastened solution and aging kinetics, while also achieving improved strength and toughness via microstructural refinement. The resultant processing parameters reduced energy consumption by decreasing furnace times and employing induction heating in place of conventional resistive heating. Several commercial aluminum alloys and model ferrous alloys were investigated, and the microstructural and mechanical property results will be presented.This work is supported by the Critical Materials Institute, an Energy Innovation Hub funded by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office and under the Advanced Manufacturing Office award number DE-EE0009131.

9:20 AM Break

9:40 AM
Diffusion Pathway of Dopant Elements in Grain Boundary Engineered Al Alloys: Tianjiao Lei¹; Jungho Shin²; Daniel Gianola²; Timothy Rupert¹; ¹University of California Irvine; ²University of California Santa Barbara
    Grain boundary engineering can improve the thermal stability and accelerate densification of nanoscale grain structure. In this study, dopant elements (Mg, Fe, Ni, and Y) were deliberately selected to enable grain boundary segregation and formation of amorphous grain boundary complexions in Al alloys fabricated using a powder metallurgy approach. The alloys showed grain sizes <60 nm and densities >99% after hot pressing, with full density connected directly to the complexion formation. In addition to grain boundary segregation and complexion formation, microstructural characterization revealed nanorod precipitates with a core-shell structure at grain boundaries, with the chemistry of the shell being the same as that of amorphous complexions. Moreover, the nanorods were observed within intermetallic particles. Therefore, a diffusion pathway of the dopants is identified, which first segregate to grain boundaries, then form amorphous complexions, subsequently diffuse to the nanorod shell, and finally combine with Al to form intermetallic phases.

10:00 AM
Experimental Investigation to Understand the Relationship between Microstructure and Electrical/Thermal Properties of Al-Ni alloys: Sunyong Kwon¹; Richard Michi²; Amit Shyam¹; Dongwon Shin¹; ¹Oak Ridge National Laboratory; ²Northwestern University
    The demand for lightweight alloys with improved thermal management capabilities is getting higher with the increasing demand for electric vehicles (EVs). Hence, a comprehensive study is required to elucidate the relationship between microstructure and physical properties needed for EVs, such as conductivities and hardness of Al-alloys. We present a systematic experimental study on the effect of microstructural evolution of the Al3Ni eutectic phase in Al-Ni alloys on electrical and thermal properties. In addition, our experimental investigation on the role of microalloying elements, i.e., Ti, V, and Zr, and their propensity for segregation at the Al/Al3Ni interface will be presented. We also investigate the interplay between conductivities and mechanical properties as a function of microstructure. The research was sponsored by Oak Ridge National Laboratory, the Department of Energy, Vehicle Technologies Office, and Powertrain Materials Core Program.