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Kustas, Andrew

Publications and source records attributed to Kustas, Andrew.

At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Refractory high entropy alloy compact heat exchanger

Several innovative technologies, including pressure-drop minimization, advanced refractory high entropy alloys, and advanced manufacturing can provide a compact heat exchanger that extends the state-of-the-art heat-exchanger operating range. The compact heat exchanger can reduce pressure drop losses by 100 to 500%, while retaining most of the heat transfer. The compact heat exchanger can be fabricated from refractory high entropy alloys that have favorable corrosion, thermal fatigue, and creep properties at high temperatures and pressures. Therefore, the compact heat exchanger using high entropy alloys can operate at >800° C. and 80 bars.

Kustas, Andrew↗
DOE OSTI2022

High-Strain Rate Spall Strength Measurement for CoCrFeMnNi High-Entropy Alloy

In this study, we experimentally investigate the high stain rate and spall behavior of Cantor high-entropy alloy (HEA), CoCrFeMnNi. First, the Hugoniot equations of state (EOS) for the samples are determined using laser-driven CoCrFeMnNi flyers launched into known Lithium Fluoride (LiF) windows. Photon Doppler Velocimetry (PDV) recordings of the velocity profiles find the EOS coefficients using an impedance mismatch technique. Following this set of measurements, laser-driven aluminum flyer plates are accelerated to velocities of 0.5–1.0 km/s using a high-energy pulse laser. Upon impact with CoCrFeMnNi samples, the shock response is found through PDV measurements of the free surface velocities. From this second set of measurements, the spall strength of the alloy is found for pressures up to 5 GPa and strain rates in excess of 106 s−1. Further analysis of the failure mechanisms behind the spallation is conducted using fractography revealing the occurrence of ductile fracture at voids presumed to be caused by chromium oxide deposits created during the manufacturing process.

36 MATERIALS SCIENCE↗