About

Prof. Hosemann’s career started at the Montanuniversitaet Leoben in Austria where he received his PhD and MS degree in material science. He joined Los Alamos National Laboratory in 2005 as a graduate research assistant and continued as a Post doc from 2008-2010 before joining UC Berkeley’s nuclear engineering department. His research features experimental material science for extreme environments especially nuclear environments. His focus is on structural materials used for nuclear components (fission, fusion, spallation, etc.) while developing a basic understanding of the materials degradation processes and resulting consequences to engineering application. His research interests include small scale materials testing on irradiated and unirradiated structural materials for nuclear applications, investigating new advanced structural materials concepts such as oxide dispersion strengthened steels, SiC/SiC composites, and additive manufactured components using accelerated materials testing via ion beam irradiations, as well as studying liquid metal corrosion of structural materials for nuclear applications to develop improved alloying concepts and system operating techniques.

Research topics

• Materials science
• Metallurgy
• Computer Science
• Engineering
• Physics
• Physical chemistry
• Atomic physics
• Nuclear physics
• Computational chemistry
• Nuclear engineering
• Chemistry
• Mechanical engineering
• Optoelectronics
• Condensed matter physics
• Nanotechnology
• Optics
• Composite material

Selected publications

• Polycrystal plasticity modeling of irradiation-induced localized flow at grain boundaries in stainless steels

  SSRN Electronic Journal · 2026-01-01

  preprintOpen access
  PublisherDOI

• Bi‐Continuous W‐Rich Refractory High Entropy Alloy‐Cu Composite: Toward Material Innovation of Nuclear Reactor Coolant System

  Small Methods · 2025-05-30

  articleOpen access

  Abstract Refractory high‐entropy alloys (RHEAs) are considered promising candidate materials for next‐generation nuclear reactors due to their superior mechanical strength, irradiation resistance, and thermal stability at high temperatures. However, the significant positive heat of mixing between refractory alloying elements and Cu, commonly used in cooling systems, poses challenges in forming composite structures. This study addresses the issue using a liquid metal dealloying (LMD) process. A precursor alloy (WTaVTi) with a directional dendrite‐interdendrite structure is fabricated and reacted with molten Cu at 1200 °C for 96 h. This approach produced a RHEA‐Cu composite with a stable interface between RHEA (W 31.5 Ta 30.9 V 21.4 Ti 14.3 ) and Cu, featuring a spontaneously formed W‐rich interlayer that enhances interfacial bonding. The composite showed excellent irradiation resistance, with 30% less swelling under α‐ion irradiation than pure W. It also exhibited low thermal conductivity at room temperature, but reached ≈120 W m −1 ·K −1 at ≈650 °C, surpassing pure W. This temperature‐dependent rise in κ, with a positive gradient of +0.075 W m −1 ·K − 2 , is attributed to decreasing diffuse mismatch at elevated temperatures. The large‐scale reaction and stable microstructure achieved through LMD process highlight its industrial potential. This work offers a strategy for developing high‐performance materials by combining RHEA's radiation resistance with Cu's thermal conductivity for extreme environments.

  PublisherOA PDFDOI

• Corrosion sensitivity of nickel-based Alloy Inconel 600 in pressurized water reactor water chemistry: Can KOH replace LiOH?

  Corrosion Science · 2025-06-04 · 6 citations

  articleOpen access

  Lithium hydroxide (LiOH) has been used to balance water acidity against boric acid moderators in the primary water of Western pressurized water reactor (PWR) designs for decades. However, the demand and the cost of lithium-7 has grown significantly since 2015. Potassium hydroxide (KOH) has been identified as a suitable and cost-effective substitute for LiOH and has been used successfully in Russian PWR designs for more than 40 years. However, it is important to know if alloys and water conditions used in Western PWR’s (Alloy 600) are similarly compatible with KOH additions. This work is focused on the aqueous corrosion behaviors of Alloy 600 with LiOH versus KOH additions at normal operating concentrations and crevice water chemistry at simulated PWR primary water conditions. TEM was used to characterize the formed oxide through diffraction analysis; SIMS was used to probe the cation ingress into the material; Atom probe tomography was used to determine the 3D elemental distribution within the oxide/metal structures; finally electrochemical impedance spectroscopy was used to discuss the structure and corrosion resistance of the oxide films. These advanced characterization techniques complement the weight measurements which showed lower mass gain in KOH than LiOH crevice water due to less oxide formation. Overall, the use of KOH as a potential alternative to LiOH in PWR is discussed. • Inconel 600 was corroded in PWR conditions at 325 C with KOH vs. LiOH • Normal operating concentrations of K vs Li did not lead to significant differences. • Alloy 600 gains less mass in KOH, due to thinner oxide formation and less alkali ingress. • SIMS and APT show deeper Li + ingress than K + . • Findings show KOH to benefit Alloy 600 rather than worsen its corrosion in PWR crevice-like chemistry.

  PublisherDOI

• Irradiation-induced gas production in REBCO-based magnet materials used for future compact fusion reactors

  Journal of Applied Physics · 2025-06-16 · 2 citations

  articleOpen accessSenior author

  Nuclear fusion is an enticing alternative to current sources of energy, with multilayered Rare-Earth Barium Copper Oxide (REBCO) coated conductors deemed pivotal in the race toward fully realized, commercially viable, and magnetic confinement fusion reactors. In this study, we simulated the ion spectrum expected to evolve from REBCO's nickel-based Hastelloy C-276 substrate and copper stabilizer in an affordable robust compact-like reactor. We then emulated this gas production through helium implantation to investigate changes in materials and superconducting properties. Our results revealed that the substrate and stabilizer are capable of producing protons energetic enough to recoil throughout the tape thickness in appreciable doses, and alphas energetic enough to deposit 7.54 × 1014 ions/cm2 or 50.1 helium appm in the superconducting layer over a 30-year reactor lifetime. The superconducting layer of SuperPower® tapes exhibited at least double the swelling rate of the other major layers, and both SuperPower and Fujikura Ltd. tapes displayed microstructural changes in the REBCO layer not observed in isotropic metals. For the estimated lifetime fluence, the Fujikura tapes showed a ∼1 K reduction in critical temperature and a 32% degradation in critical current for compact reactor-relevant conditions (16 T, 20 K). Nuclear transmutation, low-temperature solder implantations, gas-ion evolution, the influence of gas production on vortex dynamics, and other related considerations are also discussed.

  PublisherDOI

• Bi‐Continuous W‐Rich Refractory High Entropy Alloy‐Cu Composite: Toward Material Innovation of Nuclear Reactor Coolant System (Small Methods 12/2025)

  Small Methods · 2025-12-01

  articleOpen access

  Inside Back Cover In article number 2500667, Park and co-workers develop a novel RHEA-Cu composite using a liquid metal dealloying process. The resulting bi-continuous structure synergistically combines the high thermal conductivity of Cu channels for efficient heat dissipation with the superior mechanical strength and irradiation resistance of the RHEA matrix to withstand damage. This work offers a new strategy for creating high-performance materials for extreme environments, such as next-generation nuclear reactors.

  PublisherOA PDFDOI

• Micromechanical and microstructural effects of high dose helium implantation in single crystal vanadium

  Journal of Nuclear Materials · 2025-01-27 · 1 citations

  articleOpen accessCorresponding

  Vanadium alloys are candidates for fusion applications. helium and radiation effects in vanadium and its alloy is studied to understand the performance of these materials in a radiation environment and to bring insight into the effects of body centered cubic alloys in general. In this work we performed low energy ion beam implantation to achieve blistering and surface near effects and understand the blister failure mode and mechanical property changes due to radiation damage and helium content. Micro-compression testing via a novel procedure as well as 4D STEM were conducted. It was found that helium bubbles connect and generate a critical crack. The helium bubbles cause a high yield strength and large residual stress. The subsequent blistering causes severe strain in the irradiated material and the deformed material rotates its crystal.

  PublisherDOI

• A Novel Machine Learning-Driven Approach to High Throughput Mechanical Testing

  JOM · 2025-01-16

  article
  PublisherDOI

• Correlated transmission electron microscopy and atom probe tomography characterization of ion irradiated Ni-based alloy Hastelloy N

  Materials Characterization · 2025-07-02

  article
  PublisherDOI

• π–π Stacking in Kerogen and Its Mechanical Impact

  ACS Applied Materials & Interfaces · 2025-02-11 · 4 citations

  articleOpen accessSenior authorCorresponding

  Kerogen is a key source of hydrocarbon production through hydraulic fracturing. However, the direct correlation between the molecular structure and mechanical properties remains unclear. Here, we employ four-dimensional scanning transmission electron microscopy (4D-STEM) to reveal heterogeneities defined by the orientation of π–π stacking domains and amorphous regions in kerogen. We observed that the morphologies of π–π stacking domains vary with kerogen maturity, ranging from small, randomly oriented grains to larger, continuous structures. Furthermore, we conduct in situ 4D-STEM tensile testing to visualize the strain distribution across these structural heterogeneities and elucidate the governing deformation mechanisms of kerogen. Our results demonstrate different mechanical responses within kerogen, suggesting that π–π stacking domains contribute to brittleness, while amorphous regions promote ductility. We believe this innovative approach to assessing the correlation between local structural order and the mechanical properties of kerogen could lead to improved geological models for optimizing the hydraulic fracturing efficiency.

  PublisherOA PDFDOI

• Experimental Evaluation of Interfacial Bonding Strength Between 304 Stainless Steel Substrate and Electrodeposited Nickel Coating Using Mesoscale Mechanical Testing Methods

  JOM · 2025-03-13 · 1 citations

  articleOpen accessSenior authorCorresponding
  PublisherOA PDFDOI

Recent grants

• MRI: Acquisition of a Multi-beam (Ga, Ne, He,) Microscope for Nanomaterials Modification and Investigation

  NSF · $1.5M · 2013–2016

• Understanding self-assembled He-bubble superlattices under deformation in materials utilizing novel experimental methods

  NSF · $354k · 2018–2022

Frequent coauthors

• D. Frazer

  Idaho National Laboratory

  76 shared

• S.A. Maloy

  Pacific Northwest National Laboratory

  68 shared

• Andrew M. Minor

  University of California, Berkeley

  45 shared

• H.T. Vo

  35 shared

• M. Balooch

  University of California, Berkeley

  30 shared

• Yujun Xie

  Shanghai Jiao Tong University

  29 shared

• Djamel Kaoumi

  North Carolina State University

  28 shared

• Daniel Kiener

  Montanuniversität Leoben

  25 shared

Education

• PhD, Chemistry

  Montanuniversität Leoben

  2008

• MS, Physics

  Montanuniversität Leoben

  2004