1、Designation: E521 96 (Reapproved 2009)1Standard Practice forNeutron Radiation Damage Simulation by Charged-ParticleIrradiation1This standard is issued under the fixed designation E521; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision
2、, 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.1NOTEEditorial corrections were made in Section 14 in November 2012.INTRODUCTIONThis practice is intended to provide
3、 the nuclear research community with recommended proceduresfor the 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 r
4、esults with those produced by reactor neutron irradiation.Such results 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 material
5、s.1. Scope1.1 This practice provides guidance on performing charged-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 measu
6、reddirectly and changes in other properties can be inferred. Thisinformation 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 ir
7、radiationconditions.1.2 The word simulation is used here in a broad 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 char
8、gedparticle irradiations such that fundamental relationships areestablished 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 1
9、3Postirradiation Examination 14-16Reporting of Results 17Correlation 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, as
10、sociated 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 to use.2. Referenced Documents2.1 ASTM Standards:2C859 Terminology Relating to Nuclear MaterialsE170 Term
11、inology Relating to Radiation Measurements andDosimetryE821 Practice for Measurement of Mechanical PropertiesDuring Charged-Particle IrradiationE910 Test Method for Application and Analysis of Helium1This practice is under the jurisdiction of ASTM Committee E10 on NuclearTechnology and Applicationsa
12、nd 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 2003 as E521 96 (2003)1.DOI: 10.1520/E0521-96R09E01.2For referenc
13、ed 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.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Con
14、shohocken, PA 19428-2959. United States1Accumulation Fluence Monitors for Reactor VesselSurveillance, E706 (IIIC)E942 Guide for Simulation of Helium Effects in IrradiatedMetals3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 Descriptions of relevant terms are found in Terminol-
15、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 speaking, the energytransfer in a single encounter must exceed the energy requiredto displace an a
16、tom from its lattice cite.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 particle.3.2.4 penetration depth, na projection of the range alongthe normal to the entry face of the
17、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 target to the point at which the particle comes torest.3.2.7 stopping power (or stopping cross secti
18、on), 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 of some quantity such as particle rangeor particle energy at a given depth.3.3 Symbols:3.3.1 A1,Z
19、1the 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 can be expressed as the product of deand the fluence.dpadisplacements per atom; a unit of radiation
20、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 arbitrary designation used here for conve-nience to denote an ion of mass 4.Tdan effective value of the e
21、nergy 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 cross section;dedenotes a spectrum-averaged value. Usual unit is barns-eVor barns-keV.4. Signific
22、ance 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,temperature, and quantity of gases present. Additional attri-butes are the lack of induced radioactivation
23、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 experiments is the investigation of radiation effects innot-yet-existing environments, such as fusi
24、on reactors.4.2 The primary shortcoming of ion bombardments stemsfrom 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 byincr
25、easing the displacement rate, even with a correspondingshift in irradiation 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
26、thispractice are intended for research purposes and not for thecertification 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
27、 charged particles is covered in Practice E821.5. Apparatus5.1 AcceleratorThe 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-M
28、eV 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 controlparticle energy, particle flux, and specimen temperature. Deci-sions regarding apparatus are therefore left to individual
29、workers with the request that accurate data on the performanceof their 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 cas
30、e ofcommercally produced metals. Additional analysis should beperformed 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 repor
31、ted inaddition to a weight basis.7. Preirradiation Heat Treatment of 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
32、it also applies tooperations where specimens are bonded to metal holders bydiffusion or by brazing. The cooling rate between annealingE521 96 (2009)12steps and between the final annealing temperature and roomtemperature should also be controlled and reported.7.2 The environment of the specimen durin
33、g heat treatmentshould be reported. This includes description of container,measure 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 metal
34、s and alloys fromGroups IV, V, and VI frequently results in changes, bothpositive and 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 perfo
35、rmed. 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 alterations in compo-sition is magnified by the nature of the specimens. They areusually very thin with a high exposed surface-to-volu
36、me ratio.Information is obtained from regions whose distance from thesurface 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 degr
37、ee of deformation. The variations indimensions of the larger piece 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 commo
38、n 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 state of deformation. Every effort should bemade to characterize completely the deformation. The param-eters which should be stated are:
39、(1) deformation process (forexample, simple tension or compression, 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 that willallow the reader to compute th
40、e 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 temperature, including an estimate of temperaturechanges caused by adiabatic work.8.2.1 Many commonly used deformation processes (forexamp
41、le, 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 before and aftereach pass. The strain rate can then be specified sufficiently bystating the deformation time of each pass.9. Preirradiatio
42、n Metallography of Specimen9.1 A general examination by light microscopy 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
43、and then un-mounted without being irradiated. The microstructure shouldbe 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 devote
44、d 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 of Specimen10.1 The surface of the specimen should be clean and flat.Details of its preparation should be reported. Electropolishingof
45、 metallic specimens is a convenient way of achieving theseobjectives 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 con
46、di-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 mechanicallypolished condition provided damage produced by polishingdoes not extend into the region of postirradiation examination.11. Dimen
47、sion 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 mm is used, its thickness should be greater than 0.1 mm.11.2 Supported specimens may be considerably thinner thanunsupported specimens
48、. The minimum thickness should be atleast fourfold greater than the 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:
49、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. The lastcase is the most desirable as it gives the closest simulation toneutron irradiation. Some techniques for introducing heliumare
