The effect of  γ-irradiation with low energies on samples of copper single crystals with oriented surfaces of (111), (100) and (621) was studied by etching technique. The etch pits show a formation of glide bands, polygonized walls and Blisters as result to irradiation

Atta, A

Gohar, I A

Megahed, A A

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Indian J. Phys. 66A  (3). 309-314 (1992)Study of the effect of y-irradiation on copper single crystals by etching technique1A Gohar, A Atta and A A MegahedDepaiunent Phy>ics, Faculty of Science, MansoOra University, Mansouta, Egypt Received M  February 199], accepted I I  April 1991Abstract ; The effea of Y-inadiation with low energies on samples of copper single crystals with oriented surfaces of (111), (100) and (621) was studied by etching technique. The etch pits show a formation of glide bands, polygonized wallaand Blisters as result to irradiation.Keywords : Copper single crystal, effect of y-itiadiation, etching technique.PACS Nos. : 81.60.-j, 6l.80.F.d1. In troduc tionIt is of great interest in the Held of materials science to answer the question how long can the surface of the materials resist the bombardment of light ions (such as H or He) or the radiation (neutron, electron or 7 -rays) without occurrence of any deftnmation. Many authors (Makin and Blewitt 1962, Yoshitawa el al 1974, Keefer and Sosin 1964 and Mifune et al 1967) had found that electron irradiation increases the yield stress of copper, aluminium and their alloys. This effect was explained on the basis of movement of dislocations. The effect of neutron irradiation between 200 and 400°C on the decoration of dislocations in copper single crystals was studied (Jackson et al 1977). Their results show inhomogeneous clusters of damage. The dislocation velocity at temperatures below lOO^K was studied (Wada ei al 1980). The long range migration of seif interstitial takes place above SO^K and small interstitial clusters and/or interstitial impurity complexes are thought to be formed in the specimen. The displaced atoms and vacancies from irradiated copper crystals that do not recombine may diffuse through the lattice and condense as aggregates depending upon the temperature or irradiation. A tendency for formation of clusters is associated with the grown-in dislocations (Jackson et al 1974). The purpose of this work is to study the effect of 7 -irradiation with low energy on the surface deformation of copper crystals with specific orientations.2 . E xp erim en ta lOriented samples of the plane surface ( 1 1 1 ), (110) and (621) from cylindrical copper single crystals were obtained, using X-ray back reflection technique and acid cut. The Cu-single© 1992 lACS310 /  A Gohar, A Atta and A A Megahedcrystals were obtained from Department of Physics, Tu-Dresden, Germany. The samples were chemically polished and flattened using a saturated solution of cupric chloride in HCiFigure 1. Dislocation configuration in as grawn copper single crystal for surface (621).(Mitchell et al 1967). The samples are immersed in a nitric acid to remove a damaged layer near the plane surfaces, and then electrolytically etched using etching solution of 2S ml HCI + 90 ml H2O + 15 ml CH3COOH + 1 ml Br2 (Marukawa 1967) before and after irradiationFigure 2. Dislocation configuration in as grawn copper single crystal for the surface (111).by y-rays using ®*Co-source of activity 453.1 KBq and of photon-energy 1173.238 KeV (the source was obtained from the lAEA-Vienna). The samples woe subjected to exposurefor continuous 144 hours. The etched surfaces were investigated using metallurgical optical microscope of the QT>e Union ME-3007.3 . Results and discussionFigures 1 and 2 show the dislocation configuration in as grown copper single crystals of surfaces (621) and (111).Study of the effect of y-irradiation ete 311Figure 3. The foimation of polygonized walls on (621) surface by irradiaiion.It is shown that the dominating defect type in copper single crystals are individual dislocations and small angle grain boundaries.Figure 4. Glide baidsfomialian on the nirface (621) efier irradiation.lA (11)312 I A  G ohar. A A n a an d  A A M c^ ah edOn irradiated (621) surfaces, etch pits appear as lines which may be due to glide bands and polygonized walls, as shown in Figures 3 and 4. These Figures, show regions free from dislocations which could be due to migration of vacancies and dislocations to create clusters in other regions. These results are in agreement with those obtained on neutron irradiaiicd surfaces (111) (Jackson 1977).Figure 5 . G lide  bands and p o ly g o n i/e d  wall.s fo m ia lio n  on tiie su rface (111 ) a fte r irradiation.The observed glide bands and polygonized walls in Figure 4 may be due to slip and climb motion of dislocations. The slip traces are also seen on (111) surface as in Figure 5.Figure 6. Blister foimation on (111) surface by irradiaUon.Some bubbles or dome like structure were observed on the etched surfaces (111) and (100) afta- irradiatiDn as seen in Figures 6 and 7. Such structures could be formed as a result of the migration of vacancies and dislocations. Several slips have taken place along crystallographic dircetiems as shown in Figure 7.Study of the effect of y-irradiation ete 3 13Figure 7. Blister and Dome like slniaurc on (100) surface after irradiaUon.Such Structure of bubbles formation was earlier observed on gold samples, after bombardment with 3.52 MeV particles (Paszti et al 1981).They attributed this structure to the implantation of He ions with high doses. Some of the formed bubbles or blister structure on (621) surface were opened chemically as a result of several re-polishing and re-etching of the sample surfaces (see Figure 8).Figure 8. Open-Blisters on the surface (621) by re-polishing and le-etching.The bubbles or blisters can not be represented as etch pits which correspond to dislocation lines. This is clear after comparing these few bubbles with etch pits which covered all surfaces of the samples as shown in Figure 8. As a results of exposing Cu- single crystals to low energy of y-rays it can be concluded th a t:i) The dislocation density is increased,ii) Formation of glid bands and polygon walls takes place.iii) Formation of clusters as a result of the movement of vacancies and dislocations occurs,iv) Bubbles or blisters are formed as agglomeration of vacancies.314 IA  Gohar, A Alta and A A MegahedR eferencesJackson P J, Black K E, Nathanson P D K and Spalding D R 1977 Phil. Mag. 35 509Jackson P J, Kemm K and Spalding D R 1974 Proc. 8th fnt. Congress on Electron Microscopy Canberra Vol. 1 626Keefer D and Sosin A 1964 Acta Metall. 12 969Makin M J and Blewitt T H 1962 Acta Metall 10 241Marukawa K 1967 Japan J. Appl. Phys. 6 944Mifune T, Mcshii M and Ono K 1967 Appl. Phys Lett. 11 282Mitchell J W. Chevner J C. Hockey P J and Monaghan J P 1967 Canad. J  Phys. 45Pas7li F, Pogany L, Mezey G, Kotai E, Manuaba A, Poes L. Gyulai J and Lohner T 1981 J  Nucl. Mater 98 11 Wada M, Meshii M and Marukawa K 1980 Phys. Stat. Sol. (a) 57 345 Yoshiuwa I, Naramoto H and Kamada K 1974 J. Phys. 5oc. Jpn. 36 202

Study of the Effect of γ-Irradiation on Copper Single Crystals by Etching Technique

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Study of the Effect of γ-Irradiation on Copper Single Crystals by Etching Technique

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