1、Designation: E521 16Standard Practice forInvestigating the Effects of Neutron Radiation DamageUsing Charged-Particle Irradiation1This standard is issued under the fixed designation E521; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revisi
2、on, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.INTRODUCTIONThis practice is intended to provide the nuclear research community with recommended proceduresfor usi
3、ng charged-particle irradiation to investigate neutron radiation damage mechanisms as asurrogate for neutron irradiation. It recognizes the diversity of energetic-ion producing devices, thecomplexities in experimental procedures, and the difficulties in correlating the experimental resultswith those
4、 produced by reactor neutron irradiation. Such results may be used to estimate densitychanges and the changes in microstructure that would be caused by neutron irradiation. Theinformation can also be useful in elucidating fundamental mechanisms of radiation damage in reactormaterials.1. Scope1.1 Thi
5、s practice provides guidance on performing charged-particle irradiations of metals and alloys, although many of themethods may also be applied to ceramic materials. It isgenerally confined to studies of microstructural and micro-chemical changes induced by ions of low-penetrating powerthat come to r
6、est in the specimen. Density changes can bemeasured directly and changes in other properties can beinferred. This information can be used to estimate similarchanges that would result from neutron irradiation. Moregenerally, this information is of value in deducing the funda-mental mechanisms of radi
7、ation damage for a wide range ofmaterials and irradiation conditions.1.2 Where it appears, the word “simulation” should beunderstood to imply an approximation of the relevant neutronirradiation environment for the purpose of elucidating damagemechanisms. The degree of conformity can range from poor
8、tonearly exact. The intent is to produce a correspondencebetween one or more aspects of the neutron and chargedparticle irradiations such that fundamental relationships areestablished between irradiation or material parameters and thematerial response.1.3 The practice appears as follows:SectionAppar
9、atus 4Specimen Preparation 510Irradiation Techniques (including Helium Injection) 1112Damage Calculations 13Postirradiation Examination 1416Reporting of Results 17Correlation and Interpretation 18221.4 The values stated in SI units are to be regarded asstandard. No other units of measurement are inc
10、luded in thisstandard.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior
11、to use.2. Referenced Documents2.1 ASTM Standards:2C859 Terminology Relating to Nuclear MaterialsE170 Terminology Relating to Radiation Measurements andDosimetryE821 Practice for Measurement of Mechanical PropertiesDuring Charged-Particle IrradiationE910 Test Method for Application and Analysis of He
12、liumAccumulation Fluence Monitors for Reactor VesselSurveillance, E706 (IIIC)E942 Guide for Simulation of Helium Effects in IrradiatedMetals1This practice is under the jurisdiction of ASTM Committee E10 on NuclearTechnology and Applicationsand is the direct responsibility of SubcommitteeE10.08 on Pr
13、ocedures for Neutron Radiation Damage Simulation.Current edition approved Oct. 1, 2016. Published December 2016. Originallyapproved in 1976. Last previous edition approved in 2009 as E521 96 (2009)2.DOI: 10.1520/E0521-16.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact
14、 ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13. Terminology3.1 Definiti
15、ons of Terms Specific to This Standard:3.1.1 Descriptions of relevant terms are found in Terminol-ogy C859 and Terminology E170.3.2 Definitions:3.2.1 damage energy, nthat portion of the energy lost byan ion moving through a solid that is transferred as kineticenergy to atoms of the medium; strictly
16、speaking, the energytransfer in a single encounter must exceed the energy requiredto displace an atom from its lattice site.3.2.2 displacement, nthe process of dislodging an atomfrom its normal site in the lattice.3.2.3 path length, nthe total length of path measuredalong the actual path of the part
17、icle.3.2.4 penetration depth, na projection of the range alongthe normal to the entry face of the target.3.2.5 projected range, nthe projection of the range alongthe direction of the incidence ion prior to entering the target.3.2.6 range, nthe distance from the point of entry at thesurface of the ta
18、rget to the point at which the particle comes torest.3.2.7 stopping power (or stopping cross section), ntheenergy lost per unit path length due to a particular process;usually expressed in differential form as dE/dx.3.2.8 straggling, nthe statistical fluctuation due to atomicor electronic scattering
19、 of some quantity such as particle rangeor particle energy at a given depth.3.3 Symbols:3.3.1 A1,Z1the atomic weight and the number of thebombarding ion.A2,Z2the atomic weight and number of the atoms of themedium undergoing irradiation.depadamage energy per atom; a unit of radiation expo-sure. It ca
20、n be expressed as the product of deand the fluence.dpadisplacements per atom; a unit of radiation exposuregiving the mean number of times an atom is displaced from itslattice site. It can be expressed as the product of dand thefluence.heavy ionused here to denote an ion of mass 4.light ionan arbitra
21、ry designation used here for conve-nience to denote an ion of mass 4.Tdan effective value of the energy required to displace anatom from its lattice site.d(E)an energy-dependent displacement cross section; ddenotes a spectrum-averaged value. Usual unit is barns.de(E)an energy-dependent damage energy
22、 cross section;dedenotes a spectrum-averaged value. Usual unit is barns-eVor barns-keV.4. Significance and Use4.1 A characteristic advantage of charged-particle irradia-tion experiments is precise, individual, control over most of theimportant irradiation conditions such as dose, dose rate,temperatu
23、re, and quantity of gases present. Additional attri-butes are the lack of induced radioactivation of specimens and,in general, a substantial compression of irradiation time, fromyears to hours, to achieve comparable damage as measured indisplacements per atom (dpa). An important application ofsuch e
24、xperiments is the investigation of radiation effects thatmay be obtained in environments which do not currently exist,such as fusion reactors.4.2 The primary shortcoming of ion bombardments stemsfrom the damage rate, or temperature dependences of themicrostructural evolutionary processes in complex
25、alloys, orboth. It cannot be assumed that the time scale for damageevolution can be comparably compressed for all processes byincreasing the displacement rate, even with a correspondingshift in irradiation temperature. In addition, the confinement ofdamage production to a thin layer just (often ;1 m
26、) below theirradiated surface can present substantial complications. Itmust be emphasized, therefore, that these experiments and thispractice are intended for research purposes and not for thecertification or the qualification of materials.4.3 This practice relates to the generation of irradiation-i
27、nduced changes in the microstructure of metals and alloysusing charged particles. The investigation of mechanical be-havior using charged particles is covered in Practice E821.5. Apparatus5.1 AcceleratorThe major item is the accelerator, whichin size and complexity dwarfs any associated equipment.Th
28、erefore, it is most likely that irradiations will be performedat a limited number of sites where accelerators are available (a1-MeV electron microscope may also be considered an accel-erator).5.2 Fixtures for holding specimens during irradiation aregenerally custom-made as are devices to measure and
29、 controlparticle energy, particle flux (fluence rate), and specimentemperature. Decisions regarding apparatus are therefore left toindividual workers with the request that accurate data on theperformance of their equipment be reported with their results.6. Composition of Specimen6.1 An elemental ana
30、lysis of stock from which specimensare fabricated should be known. The manufacturers heatnumber and analysis are usually sufficient in the case ofcommercally produced metals. Additional analysis should beperformed after other steps in the experimental procedure ifthere is cause to believe that the c
31、omposition of the specimenmay have been altered. It is desirable that uncertainties in theanalyses be stated and that an atomic basis be reported inaddition to a weight basis.7. Preirradiation Heat Treatment of Specimen7.1 Temperature and time of heat treatments should be wellcontrolled and reported
32、. This applies to intermediate annealsduring fabrication, especially if a metal specimen is to beirradiated in the cold-worked condition, and it also applies tooperations where specimens are bonded to metal holders bydiffusion or by brazing. The cooling rate between annealingsteps and between the fi
33、nal annealing temperature and roomtemperature should also be controlled and reported.E521 1627.2 The environment of the specimen during heat treatmentshould be reported. This includes description of container,measure of vacuum, presence of gases (flowing or steady), andthe presence of impurity absor
34、bers such as metal sponge. Anydiscoloration of specimens following an anneal should bereported.7.3 High-temperature annealing of metals and alloys fromGroups IV, V, and VI frequently results in changes, bothpositive and negative, in their interstitial impurity content.Since the impurity content may
35、have a significant influence onvoid formation, an analysis of the specimen or of a companionpiece prior to irradiation should be performed. Other situations,such as selective vaporization of alloy constituents duringannealing, would also require a final analysis.7.4 The need for care with regard to
36、alterations in compo-sition is magnified by the nature of the specimens. They areusually very thin with a high exposed surface-to-volume ratio.Information is obtained from regions whose distance from thesurface may be small relative to atomic diffusion distances.8. Plastic Deformation of Specimen8.1
37、 When plastic deformation is a variable in radiationdamage, care must be taken in the geometrical measurementsused to compute the degree of deformation. The variations indimensions of the larger piece from which specimens are cutshould be measured and reported to such a precision that astandard devi
38、ation in the degree of plastic deformation can beassigned to the specimens. A measuring device more accurateand precise than the common hand micrometer will probablybe necessary due to the thinness of specimens commonlyirradiated.8.2 The term cold-worked should not stand alone as adescription of sta
39、te of deformation. Every effort should bemade to characterize completely the deformation. The param-eters which should be stated are: (1) deformation process (forexample, simple tension or compression, swaging, rolling,rolling with applied tension); (2) total extent of deformation,expressed in terms
40、 of the principal orthogonal natural straincomponents (1, 2, 3) or the geometric shape changes that willallow the reader to compute the strains; (3) procedure used toreach the total strain level (for example, number of rollingpasses and reductions in each); (4) strain rate; and (5) defor-mation temp
41、erature, including an estimate of temperaturechanges caused by adiabatic work.8.2.1 Many commonly used deformation processes (forexample, rolling and swaging) tend to be nonhomogeneous. Insuch cases the strain for each pass can be best stated by thedimensions in the principal working directions befo
42、re and aftereach pass. The strain rate can then be specified sufficiently bystating the deformation time of each pass.9. Preirradiation Metallography of Specimen9.1 A general examination by light microscopy andtransmission-electron microscopy should be performed on thespecimen in the condition in wh
43、ich it will be irradiated. Insome cases, this means that the examination should be done onspecimens that were mounted for irradiation and then un-mounted without being irradiated. The microstructure shouldbe described in terms of grain size, phases, precipitates,dislocations, and inclusions.9.2 Asec
44、tion of a representative specimen cut parallel to theparticle beam should be examined by light microscopy. Atten-tion should be devoted to the microstructure within a distancefrom the incident surface equal to the range of the particle, aswell as to the flatness of the surface.10. Surface Condition
45、of Specimen10.1 The surface of the specimen should be clean and flat.Details of its preparation should be reported. Electropolishingof metallic specimens is a convenient way of achieving theseobjectives in a single operation. The possibility that hydrogenis absorbed by the specimen during electropol
46、ishing should beinvestigated by analyses of polished and nonpolished speci-mens. Deviations in the surface from the perfect-planar condi-tion should not exceed, in dimension perpendicular to theplane, 10 % of the expected particle range in the specimen.10.2 The specimen may be irradiated in a mechan
47、icallypolished condition provided damage produced by polishingdoes not extend into the region of postirradiation examination.11. Dimension of Specimen Parallel to Particle Beam11.1 Specimens without support should be thick enough toresist deformation during handling. If a disk having a diameterof 3
48、mm is used, its thickness should be greater than 0.1 mm.11.2 Supported specimens may be considerably thinner thanunsupported specimens. The minimum thickness should be atleast fourfold greater than the distance below any surface fromwhich significant amounts of radiation-produced defects couldescape
49、. This distance can sometimes be observed as a void-freezone near the free surface of an irradiated specimen.12. Helium12.1 Injection:12.1.1 Alpha-particle irradiation is frequently used to injecthelium into specimens to simulate the production of heliumduring neutron irradiations where helium is produced bytransmutation reactions. Helium injection may be completedbefore particle irradiation begins. It may also proceed incre-mentally during interruptions in the particle irradiation or itmay proceed simultaneously with particle irradiation. Th
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