Showing 126 results for Author: Alex J. Plotkowski
Sep, 2026
Journal
The use of recycled or scrap or secondary aluminum to manufacture high pressure die castings (HPDC) for structural applications is an opportunity to reduce cost, energy expenditure and emission of greenhouse gases. Technical challenges that must be overcome to achieve this on a large scale include scrap sorting and availability of alloys that can take such feedstock while…
Sep, 2026
ORNL Report
Under the Rapid Qualification technical area of the Advanced Materials and Manufacturing Technologies program, simulation-based approaches are being developed towards understanding the linkage between laser powder bed fusion part geometry, processing, material structure, and properties and potential sources of variability thereof. Previous modeling and simulation work unde…
Sep, 2026
Journal
We investigated the high-temperature behavior of binary eutectic nickel-base alloys with low-solubility elements, towards developing alloys with new combinations of structural and functional (e.g. thermal or corrosion) properties. Based on thermodynamic screening, we cast binary near-eutectic Ni-B, Ni-Ca, Ni-Ce, Ni-La, Ni-Y, and Ni-Zr alloys and characterized their microst…
Aug, 2026
Conference Paper
Oak Ridge National Laboratory (ORNL) has recently launched an effort to economically expand the North American aluminum supply chain by designing and developing a new family of Al-Mg-Si-Fe-Mn structural die cast aluminum alloys that can be made from up to 100% mixed 5xxx and 6xxx series automotive post-consumer sheet scrap and do not require heat treatment. The goal is to…
Aug, 2026
Journal
Raptor is an efficient Python library for simulating stochastic lack-of-fusion (sLoF) defects in additive manufacturing (AM) processes. These defects arise from stochastic variations in the melt pool boundary leading to undermelting from insufficient overlap between adjacent melt pools or successive layers (Grasso & Colosimo, 2017; Khairallah et al., 2016). Performance var…
Aug, 2026
Journal
Non-equilibrium phase formation and the interaction between the nucleation and solidification of competing phases are significant challenges in aluminum alloy design, as key properties such as ductility heavily depend on the grain morphologies and phases present in solidified castings. This manuscript expands upon existing multiphase cellular automata (CA) modeling work to…
Jul, 2026
Journal
Additive Manufacturing (AM) of alloys holds significant promise as a disruptive technology in various industries, yet its adoption is often hindered by challenges in achieving consistent part quality. These issues are primarily due to the complex process-microstructure-property (PSP) relationships inherent to AM. Computational models can greatly aid in understanding these…
May, 2026
Journal
It has been recently demonstrated that eutectic alloys processed by additive manufacturing have excellent high-temperature mechanical properties. We suggest that nickel-base eutectic alloys may enable new combinations of structural and functional properties. To this end, we investigate the processability, microstructure, and thermal stability of five, binary near-eutectic…
May, 2026
Journal
As-solidified microstructures of near-eutectic alloys often contain multiple primary phases that are not expected from equilibrium phase diagrams. Such microstructures are caused by cooling-rate-dependent solidification pathways, a factor not captured by the Scheil–Gulliver model or variations thereof. Here, we present a model and algorithm that incorporate the critical nu…
May, 2026
Journal
This study examines the processing behavior, microstructure, surface roughness, and hardness properties of an aluminum alloy containing 8.2 Ce, 4.5 Ni, 0.5 Mn, and 0.7 Zr (wt%) fabricated using laser powder bed fusion. Sixty samples were produced across a range of laser powers, scan speeds, and hatch spacings to evaluate their effect on porosity, hardness, and microstructu…
Mar, 2026
Journal
The high cycle fatigue behavior of laser powder bed fusion processed AlSi10Mg has been investigated at 350 °C (T/Tm ∼ 0.7). The alloy exhibited a fatigue strength of 30 MPa defined by runout after 107 cycles at a conventional loading frequency of 20 Hz, corresponding to a notable fatigue strength to ultimate tensile strength ratio of 0.73. The surprising fatigue resistance…
Mar, 2026
Journal
Directed Energy Deposition (DED) offers rapid large scale fabrication, but difficulty in delivering consistent microstructures and properties hinders the use of DED fabricated components in safety or performance critical applications. Variability stems from the complex thermal cycles generated by the toolpath used to print the required geometry. Several practical methods h…