Stuart Maloy

CWRU, Materials Science and Engineering, Alumnus

Followers

Following

Co-authors

Public Views

Interests

Uploads

Papers by Stuart Maloy

Positron annihilation spectroscopy of proton irradiated single crystal BCC iron

by Farida Selim and Stuart Maloy

Journal of Nuclear Materials, 2006

Positron annihilation spectroscopy was used to analyze the open-volume defects created in single ... more Positron annihilation spectroscopy was used to analyze the open-volume defects created in single crystal, body-centered cubic iron irradiated with 1.0 MeV protons. The effects of irradiation dose and temperature were investigated. A novel technique utilizing a Bremsstrahlung beam to activate and induce positron decay in the bulk specimens, followed by Doppler broadening spectroscopy, was employed. No open-volume defects were detected in the 0.03 dpa irradiated specimens. However, the 0.3 dpa specimens exhibited an increase in the S parameter when compared to the 0.03 dpa specimens at 723 K. The 0.3 dpa specimen at 723 K indicated an increase in open-volume defects, as the radiation temperature increased compared to the 573 K, 0.3 dpa specimen. This was thought to be a consequence of the void and dislocation loop density decreasing while the void and dislocation loop diameter was increasing.

Download

Materials issues in a high power spallation target

High energy proton irradiation can have significant effects on the mechanical properties of struc... more High energy proton irradiation can have significant effects on the mechanical properties of structural materials. Many future accelerator driven systems are concerned with these effects. These systems can be categorized into those proposing a liquid metal target: mercury for SNS and JSNS and lead bismuth for AFCI, Megapie and MYRRHA and those proposing a solid target: LANSCE, KEK, CIAE concept, ISIS and TRADE. Under high energy proton irradiation, spallation can occur (energies greater than 5 MeV) which in addition to typical effects observed from irradiation in a fission spectrum results in higher primary knock-on energies, larger displacement cascades and significantly increased generation rates of helium and hydrogen. These effects of irradiation are discussed in the following papers on austenitic steels (316L, 316LN and welds), ferritic/martensitic steels (9Cr-1Mo, F82H and Optifer) and AlMg3.

Download

Corrosion Testing in Support of the Accelerator Production of Tritium Program

Page 1. CORROSION TESTING IN SUPPORT OF THE ACCELERATOR PRODUCTION OF TRITIUM PROGRAM GT Chandler... more

Materials Selection and Qualification Processes at a High-Power Spallation Neutron Source

Materials Characterization, 1999

The accelerator at the Los Alamos Neutron Science Center (LANSCE) at the Los Alamos National Labo... more The accelerator at the Los Alamos Neutron Science Center (LANSCE) at the Los Alamos National Laboratory has been in operation since 1972. Development of materials for service in high voltage applications, high-vacuum systems, magnetic and electric fields, high particle radiation fluxes, and corrosive atmospheres has been ongoing during this period. Materials were initially selected based on performance at other facilities and at fission reactors. Modification to materials selection and specifications were made based on experience at LANSCE. Plans for higher power accelerators, such as the one proposed for the Accelerator Production of Tritium Project, have led to a realization that dedicated materials radiation damage effects studies are necessary to ensure adequate service lifetimes and to allow planning for preventative maintenance. Published by Elsevier Science Inc.

Download

Precipitation of Mo5Si3 in MoSi2

Journal of Materials Research, 1993

... Xiao, and AH Heuer Case Western Reserve University, Cleveland, Ohio 44106 J. Garrett McMaster... more

Report of the Snowmass T4 Working Group on Particle Sources:Positron Sources, Antiproton Sources, and Secondary Beams

This report documents the activities of the Snowmass 2001 T4 Particle Sources Working Group. T4 w... more This report documents the activities of the Snowmass 2001 T4 Particle Sources Working Group. T4 was charged with examining the most challenging aspects of positron sources for linear colliders and antiproton sources for proton-antiproton colliders, and the secondary beams of interest to the physics community that will be available from the next generation of high-energy particle accelerators. The leading issues, limiting technologies, and most important R&D efforts of positron production, antiproton production, and secondary beams are discussed in this paper. A listing of T4 Presentations is included.

Download

Radiation Damage from Atomic to Meso-Scales in Extreme Environments

Overcoming radiation damage degradation is a key rate-controlling step in fusion materials develo... more Overcoming radiation damage degradation is a key rate-controlling step in fusion materials development. New science, approaches, and facilities are needed at multiple scales. Understanding is needed at the atomic scale of the behavior of materials subject to extreme radiation doses and mechanical stress in order to synthesize new materials that can tolerate such conditions. Current computational and experimental research into radiation-tolerant materials will be described. Plans for future irradiation facilities and science are also described. The Matter Radiation Interactions in Extremes (MaRIE) concept is a National User Facility to realize the vision of 21 st century materials research and development. The Fission and Fusion Materials Facility (F 3) segment of MaRIE proposes to use the present proton linac at Los Alamos with a power upgrade to drive a spallation neutron source that can provide the required radiation environment. Importantly, F 3 would also provide the capability ...

Download

Failure analysis of a radio-activated accelerator component

ABSTRACT

Status of materials handbooks for particle accelerator and nuclear reactor applications

Download

The high temperature three point bend testing of proton irradiated 316L stainless steel and Mod 9Cr–1Mo

... NM, 87545, 2001, 20 p. [2] SA Maloy, WF Sommer, MR James, T. Romero, M. Lopez, E. Zimmermann ... more

Tensile properties of the NLF reduced activation ferritic/martensitic steels after irradiation in a fast reactor spectrum to a maximum dose of 67 dpa

by Stuart Maloy and A. Kimura

The NLF series of steels are reduced activation ferritic-martensitic (RAFM) steels that are a par... more The NLF series of steels are reduced activation ferritic-martensitic (RAFM) steels that are a part of the Japanese program to produce a suitable reduced activation ferritic-martensitic steel for the ITER project. Published reports on the NLF steels after about 35 dpa at 400°C by Kurishita et al., indicate that these steels have similar strength and better ductility than other RAFM steels such as the JLF steels and F82H irradiated at 400°C to similar doses. The tensile properties of NLF steels irradiated at $400°C to doses as high as 67 dpa are presented here. Tensile tests were conducted at a strain rate of 5 · 10 À4 s À1 at 25, 400°C, and 500°C. Variations in irradiation temperature in the range of 390-430°C had a relatively small, but definite effect on the tensile properties for tests conducted at 25, 400, and 500°C. The strongest hardening is observed for specimens irradiated at 390°C, and very little hardening is observed for specimens irradiated at 430°C. Strain rate jump tests were performed on NLF-0 and NLF-1 at 400°C after irradiation to 52 dpa. The rate sensitivity, m, is quite low, 0.003-0.005 and does not appear to be affected by irradiation at 52 dpa for an irradiation temperature of 430°C.

Download

Kinetics of the Nucleation and Growth of Helium Bubbles in bcc Iron

MRS Proceedings, 2006

Page 1. Kinetics of the Nucleation and Growth of Helium Bubbles in bcc Iron Chaitanya Suresh Deo ... more

Analysis of Beam-Induced Damage to the SLC Positron Production Target

The nominal Next Linear Collider (NLC) positron production design is based on extrapolation of th... more The nominal Next Linear Collider (NLC) positron production design is based on extrapolation of the existing SLAC Linear Collider (SLC) positron production system. Given that the SLC positron production target failed during a run, it is necessary to analyze the beam-induced damage to the target in order to validate the extrapolations on which the NLC target is based. The failed SLC target and its associated housing were sent to existing "hot-cell" facilities at LANL for analysis. The target material, a tungsten-rhenium "puck", was removed from the housing and photographed and x-rayed. Leak-checking on the cooling system was performed. Sections were then removed from the target to determine the extent of internal damage to the material. High resolution photographs were taken and extensive hardness tests were performed on the irradiated and non-irradiated areas of the target material. The results of these analyses and conclusions applicable to the NLC target design are presented in this paper.

Download

On the structure and chemistry of complex oxide nanofeatures in nanostructured ferritic alloy U14YWT

Philosophical Magazine, 2012

ABSTRACT The remarkable radiation damage resistance of nanostructured ferritic alloys (NFAs) is a... more ABSTRACT The remarkable radiation damage resistance of nanostructured ferritic alloys (NFAs) is attributed to the large numbers of matrix nanofeatures (NFs) of various types, which can enhance the recombination of displacement defects and trap transmutant helium in fine scale bubbles. Characterizing the chemistry, crystallographic structure and orientation relationships of the NFs is critical to understanding how they enhance the radiation damage resistance of NFAs. Conventional and high-resolution transmission electron microscopy and energy-dispersive spectroscopy were used to characterize the various types of NF and larger oxide phases in a model 14Cr–3 W–0.4Ti–0.25Y2O3 NFA (14YWT) hot isostatic pressed (HIP-ed) at 1150°C. Large CrTiO3 precipitates (50–300 nm) and small diffracting NFs (

In situ nanocompression testing of irradiated copper

by Stuart Maloy and Peter Hosemann

Increasing demand for energy and reduction of CO 2 emissions has revived interest in nuclear ener... more Increasing demand for energy and reduction of CO 2 emissions has revived interest in nuclear energy. Designing materials for radiation environments necessitates fundamental understanding of how radiation-induced defects alter mechanical properties. Ion beams create radiation damage efficiently without material activation, but their limited penetration depth requires small-scale testing. However, strength measurements of nano-scale irradiated specimens have not been previously performed. Here we show that yield strengths approaching macroscopic values are measured from irradiated ~400 nm diameter copper specimens. Quantitative in situ nanocompression testing in a transmission electron microscope reveals that the strength of larger samples is controlled by dislocation-irradiation defect interactions, yielding size-independent strengths. Below ~400 nm, size-dependent strength results from dislocation source limitation. This transition length-scale should be universal, but depend on material and irradiation conditions. We conclude that for irradiated copper, and presumably related materials, nano-scale in situ testing can determine bulk-like yield strengths and simultaneously identify deformation mechanisms.

Download

Terence E. Mitchell symposium on the magic of materials: Structures and properties Foreword

Metallurgical and Materials Transactions A, 2004

... GT (Rusty) Gray presented work on high strain rate deformation of Ta, while P. Peralta descri... more

Small-Scale Testing of In-Core Fast Reactor Materials

by Stuart Maloy and Peter Hosemann

Journal of Nuclear Science and Technology, 2011

Part of the Fuel Cycle R&D (FCRD) initiative in the USA is to investigate materials for high dose... more Part of the Fuel Cycle R&D (FCRD) initiative in the USA is to investigate materials for high dose application. While mechanical testing on large samples delivers direct engineering data, these types of tests are only possible if enough sample material and required hot cell capabilities are available. Smallscale materials testing methods in addition to large-scale materials testing allows insight on the same specimen and direct probing into areas of interest which are not accessible otherwise. In order to establish an empirical and research-based relationship between small-scale and large-scale materials testing, several different mechanical testing techniques were conducted on the same specimen irradiated in the Swiss spallation source irradiation program (STIP) at the Swiss spallation source (SINQ) at the Paul Scherrer Institute (PSI) up to a dose of 19 dpa. It is shown that the yield strength measured by tensile testing, microcompression testing and microhardness testing all show the same trend. In addition, focused ion beam (FIB)-based techniques also are used to produce local electrode atom probe (LEAP) samples. This procedure allows cutting samples of such a small size that no radioactivity on the prepared sample can be measured.

Download

Issues to consider using nano indentation on shallow ion beam irradiated materials

by Stuart Maloy and Peter Hosemann

ABSTRACT Ion beam irradiation is a widely used method to cause radiation damage in materials in o... more ABSTRACT Ion beam irradiation is a widely used method to cause radiation damage in materials in order to study materials degradation under radiation in a laboratory setting. Nanoindentation has become an often used tool to measure the mechanical property changes due to ion beam irradiation. While the combination of ion beam irradiation and nanoindentation is a powerful tool, difficulties arise and need to be discussed in detail. This work intends to draw attention to the potential issues one might face if nanoindentation is used to evaluate radiation induced hardening, especially if compared to other mechanical tests such as yield strength from tensile tests on irradiated materials and others. In this work we focus on issues associated with size and dose effects associated with quasi static nanoindentation on shallow irradiated Cu [1 0 0] single crystal material. It is shown that on 1 μm deep irradiated material it is not possible to correlate a single dose to a specific hardness value, rather a dose range has to be considered. However, deeper indents will always sample contributions of the unirradiated material. Moreover, the correlation between the indentation hardness and macroscopic properties is not straight forward.

Liquid metal embrittlement of silicon enriched steel for nuclear applications

by Stuart Maloy and Peter Hosemann

ABSTRACT Lead–bismuth eutectic (LBE) liquid metal is considered to act as the coolant and as spal... more ABSTRACT Lead–bismuth eutectic (LBE) liquid metal is considered to act as the coolant and as spallation neutron source for a future accelerator driven system (ADS). In addition to the highly corrosive effect of the liquid lead–bismuth eutectic, the liquid metal may also affect the mechanical integrity of the structural materials by a phenomenon called liquid metal embrittlement. Thus, although the addition of silicon to ferritic–martensitic steels has been found to strongly increase the material’s resistance to corrosion in liquid lead–bismuth environment, their mechanical properties can be strongly affected by the liquid metal environment. This paper discusses the mechanical properties of an experimental silicon enriched high Cr/high creep resistant bainitic steel when in contact with LBE. The steel’s mechanical properties were assessed by tensile testing as function of temperature in both liquid lead–bismuth eutectic and in an argon and hydrogen gas environment. It was found that the silicon enriched bainitic steel is very prone to liquid metal embrittlement between 300 and 375 C with the transition in mechanical behaviour from ductile to predominantly brittle between 200 and 300 C thus defining its the so-called ductility trough.

Nanoindentation on ion irradiated steels

by Christiane Vieh, Peter Hosemann, and Stuart Maloy

Journal of Nuclear Materials, 2009

Radiation induced mechanical property changes can cause major difficulties in designing systems o... more Radiation induced mechanical property changes can cause major difficulties in designing systems operating in a radiation environment. Investigating these mechanical property changes in an irradiation environment is a costly and time consuming activity. Ion beam accelerator experiments have the advantage of allowing relatively fast and inexpensive materials irradiations without activating the sample but do in general not allow large beam penetration depth into the sample. In this study, the ferritic/martensitic steel HT-9 was processed and heat treated to produce one specimen with a large grained ferritic microstructure and further heat treated to form a second specimen with a fine tempered martensitic lath structure and exposed to an ion beam and tested after irradiation using nanoindentation to investigate the irradiation induced changes in mechanical properties. It is shown that the HT-9 in the ferritic heat treatment is more susceptible to irradiation hardening than HT-9 after the tempered martensitic heat treatment. Also at an irradiation temperature above 550°C no detectable hardness increase due to irradiation was detected. The results are also compared to data from the literature gained from the fast flux test facility.

Download

Stuart Maloy

Uploads

Papers by Stuart Maloy

Log In