1、Designation: E 521 96 (Reapproved 2009)Standard Practice forNeutron Radiation Damage Simulation by Charged-ParticleIrradiation1This standard is issued under the fixed designation E 521; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revisio
2、n, 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 the
3、simulation of neutron radiation damage by charged-particle irradiation. It recognizes thediversity of energetic-ion producing devices, the complexities in experimental procedures, and thedifficulties in correlating the experimental results with those produced by reactor neutron irradiation.Such resu
4、lts may be used to estimate density changes and the changes in microstructure that wouldbe caused by neutron irradiation. The information can also be useful in elucidating fundamentalmechanisms of radiation damage in reactor materials.1. Scope1.1 This practice provides guidance on performing charged
5、-particle irradiations of metals and alloys. It is generallyconfined to studies of microstructural and microchemicalchanges carried out with ions of low-penetrating power thatcome to rest in the specimen. Density changes can be measureddirectly and changes in other properties can be inferred. Thisin
6、formation can be used to estimate similar changes that wouldresult from neutron irradiation. More generally, this informa-tion is of value in deducing the fundamental mechanisms ofradiation damage for a wide range of materials and irradiationconditions.1.2 The word simulation is used here in a broad
7、 sense toimply an approximation of the relevant neutron irradiationenvironment. The degree of conformity can range from poor tonearly exact. The intent is to produce a correspondencebetween one or more aspects of the neutron and chargedparticle irradiations such that fundamental relationships areest
8、ablished between irradiation or material parameters and thematerial response.1.3 The practice appears as follows:SectionApparatus 4Specimen Preparation 5-10Irradiation Techniques (including Helium Injection) 1112Damage Calculations 13Postirradiation Examination 14-16Reporting of Results 17Correlatio
9、n and Interpretation 18-221.4 The values stated in SI units are to be regarded asstandard. No other units of measurement are included 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
10、standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C 859 Terminology Relating to Nuclear MaterialsE 170 Terminology Relating to Radiation Measurementsand DosimetryE 821 Prac
11、tice for Measurement of Mechanical PropertiesDuring Charged-Particle IrradiationE 910 Test Method for Application and Analysis of HeliumAccumulation Fluence Monitors for Reactor Vessel Sur-veillance, E706 (IIIC)E 942 Guide for Simulation of Helium Effects in IrradiatedMetals3. Terminology3.1 Definit
12、ions of Terms Specific to This Standard:3.1.1 Descriptions of relevant terms are found in Terminol-ogy C 859 and Terminology E 170.3.2 Definitions:3.2.1 damage energy, nthat portion of the energy lost byan ion moving through a solid that is transferred as kinetic1This practice is under the jurisdict
13、ion of ASTM Committee E10 on NuclearTechnology and Applications and is the direct responsibility of SubcommitteeE10.08 on Procedures for Neutron Radiation Damage Simulation.Current edition approved Aug. 1, 2009. Published September 2009. Originallyapproved in 1976. Last previous edition approved in
14、2003 as E 521 96 (2003)1.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 B
15、arr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.energy to atoms of the medium; strictly speaking, the energytransfer in a single encounter must exceed the energy requiredto displace an atom from its lattice cite.3.2.2 displacement, nthe process of dislodging an atomfro
16、m its normal site in the lattice.3.2.3 path length, nthe total length of path measuredalong the actual path of the particle.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 th
17、e incidence ion prior to entering the target.3.2.6 range, nthe distance from the point of entry at thesurface of the target 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 expre
18、ssed in differential form as dE/dx.3.2.8 straggling, nthe statistical fluctuation due to atomicor electronic scattering of some quantity such as particle rangeor particle energy at a given depth.3.3 Symbols:Symbols:A1,Z1the atomic weight and the number of the bombard-ing ion.A2,Z2the atomic weight a
19、nd number of the atoms of themedium undergoing irradiation.depadamage energy per atom; a unit of radiation expo-sure. It can be expressed as the product of sdeand the fluence.dpadisplacements per atom; a unit of radiation exposuregiving the mean number of times an atom is displaced from itslattice s
20、ite. It can be expressed as the product of sdand thefluence.heavy ionused here to denote an ion of mass 4.light ionan arbitrary 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.sd(E)an energy-depen
21、dent displacement cross section; sddenotes a spectrum-averaged value. Usual unit is barns.sde(E)an energy-dependent damage energy cross section;sdedenotes a spectrum-averaged value. Usual unit is barns-eVor barns-keV.4. Significance and Use4.1 A characteristic advantage of charged-particle irradia-t
22、ion experiments is precise, individual, control over most of theimportant irradiation conditions such as dose, dose rate,temperature, and quantity of gases present. Additional at-tributes are the lack of induced radioactivation of specimensand, in general, a substantial compression of irradiation ti
23、me,from years to hours, to achieve comparable damage as mea-sured in displacements per atom (dpa). An important applica-tion of such experiments is the investigation of radiation effectsin not-yet-existing environments, such as fusion reactors.4.2 The primary shortcoming of ion bombardments stemsfro
24、m the damage rate, or temperature dependences of themicrostructural evolutionary processes in complex 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 irra
25、diation temperature. In addition, the confinement ofdamage production to a thin layer just (often ; 1 m) belowthe irradiated surface can present substantial complications. Itmust be emphasized, therefore, that these experiments and thispractice are intended for research purposes and not for thecerti
26、fication or the qualification of equipment.4.3 This practice relates to the generation of irradiation-induced changes in the microstructure of metals and alloysusing charged particles. The investigation of mechanical be-havior using charged particles is covered in Practice E 821.5. Apparatus5.1 Acce
27、leratorThe major item is the accelerator, whichin size and complexity dwarfs any associated equipment.Therefore, 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
28、Fixtures for holding specimens during irradiation aregenerally custom-made as are devices to measure and controlparticle energy, particle flux, and specimen temperature. Deci-sions regarding apparatus are therefore left to individualworkers with the request that accurate data on the performanceof th
29、eir equipment be reported with their results.6. Composition of Specimen6.1 An elemental analysis 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 beperfo
30、rmed after other steps in the experimental procedure ifthere is cause to believe that the composition 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 o
31、f Specimen7.1 Temperature and time of heat treatments should be wellcontrolled and reported. 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 ho
32、lders bydiffusion or by brazing. The cooling rate between annealingsteps and between the final annealing temperature and roomtemperature should also be controlled and reported.7.2 The environment of the specimen during heat treatmentshould be reported. This includes description of container,measure
33、of vacuum, presence of gases (flowing or steady), andthe presence of impurity absorbers 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 a
34、nd negative, in their interstitial impurity content.Since the impurity content may 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 duringa
35、nnealing, would also require a final analysis.E 521 96 (2009)27.4 The need for care with regard to 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 t
36、hesurface may be small relative to atomic diffusion distances.8. Plastic Deformation of Specimen8.1 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
37、from which specimens are cutshould be measured and reported to such a precision that astandard deviation 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
38、specimens commonlyirradiated.8.2 The term cold-worked should not stand alone as adescription of state 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,
39、 swaging, rolling,rolling with applied tension); (2) total extent of deformation,expressed in terms of the principal orthogonal natural straincomponents (1, 2, 3) or the geometric shape changes thatwill allow the reader to compute the strains; (3) procedure usedto reach the total strain level (for e
40、xample, number of rollingpasses and reductions in each); (4) strain rate; and (5) defor-mation temperature, 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 th
41、e strain for each pass can be best stated by thedimensions in the principal working directions before 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 micro
42、scopy andtransmission-electron microscopy should be performed on thespecimen in the condition in which 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 sh
43、ouldbe described in terms of grain size, phases, precipitates,dislocations, and inclusions.9.2 Asection 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
44、equal to the range of the particle, aswell as to the flatness of the surface.10. Surface Condition 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 theseobjective
45、s in a single operation. The possibility that hydrogenis absorbed by the specimen during electropolishing should beinvestigated by analyses of polished and nonpolished speci-mens. Deviations in the surface form the perfect-planar condi-tion should not exceed, in dimension perpendicular to theplane,
46、10 % of the expected particle range in the specimen.10.2 The specimen may be irradiated in a mechanicallypolished 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 su
47、pport should be thick enough toresist deformation during handling. If a disk having a diameterof 3 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
48、 distance below any surface fromwhich significant amounts of radiation-produced defects couldescape. 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 injectheliu
49、m 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. The lastcase is the most desirable as it gives the closest simulation toneutron irradiation. Some techniques for introducing heliumare set forth in Guide E 942.12.1.2 The influence of implantation temperature on h
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