Surface damage of V-Zr alloy by helium ions

Anand, M. S.; Pande, B.M.

doi:10.1016/0022-3115(91)90513-7

“…Blister formation due to the buildup of ion-implanted gas in the metal has been investigated widely in diverse metals and alloys; [5][6][7][8][9][10][11][12][13][14][15][16][17] however, there is no consensus as to the underlying cause of this phenomenon. Previous models have been based on one of two differing views: first, the concept of a buildup of pressure by agglomeration of gas atoms; and second, the concept of lateral stresses.…”

Section: Introductionmentioning

confidence: 99%

On the blister formation in copper alloys due to the helium ion implantation

Moreno¹,

Eliezer

²

1997

Metall Mater Trans A

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A new approach to the blister-formation phenomenon is discussed by means of the mathematical solution on a uniformly loaded circular plate with clamped edges (circular diaphragm). In the present investigation, it was found that blister formation depends on the mechanical properties of the alloys and the near-surface concentration of the implanted gas, which itself is contingent on the crystallographic orientation by means of the stopping power of the implanted atoms. The reported model is based on the fact that at certain depths from the surface, the pressure in the cavities approaches the yield stress of the metal and blistering starts. The thickness of this thin film depends on the mechanical properties of the specific metal. Once a blister cavity is formed, the deformation of the thin film to form a blister cap depends on the buildup of pressure in the cavity contingent on the implanted dose. For the present model, it is sufficient to say that the thickness of the blister's cap cannot be correlated with the projected range of the implantation, as assumed by other authors. The implanted helium concentration needed to buildup enough gas pressure to create a blister at a depth which is close to the projected range is higher by 50 times than the gas helium concentration in the cavity. Experimental results, such as the fact that the blisters have burst at the edge of the circular skin, where the maximum stresses are developed, and the fact that at high implantation energy (large projected range), the bursting of the blisters occurs by multilayer caps, support the present model.

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Studies on Helium Ion Irradiated NiAl Alloy

Pande

¹

,

Anand

²

1992

Phys. Stat. Sol. (a)

0

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IntroductionThe behaviour of helium in metals is of importance both from basic and technological points of view. In fusion reactors, helium will be implanted on the different components like first wall etc. Due to its low solid solubility in metals, it gets seggregated and forms bubbles affecting their properties [l]; exfoliations and blisters are also formed on the surface [2 to 41. Nickel is one of the important constituents of materials like steel which are proposed to be used in fusion reactors as first wall. The defects will be created in this material and their study is important.Defects in nickel and its alloys have earlier been studied [5 to 91. But the defects created by helium ions and their interaction with helium needs further work. Recently some work [lo, 111 on helium ion irradiation in nickel has been reported. In the present study isochronal annealings of 30 MeV a-ion irradiated nickel and nickel-aluminium alloy have been carried out using the resistivity technique.Experimental Nickel-0.5 wt% A1 and Ni-1.0 wt% A1 were made from nickel of 99.99% and aluminium of 99.99% purity. These alloys were melted in an arc furnace under inert atmosphere for a couple of times for better homogenisation. The buttons of nickel and Ni-A1 alloys were rolled down to a thickness of 0.05 cm in stages. Samples of size 1.0 x 0.5 cm2 were cut out and annealed at 1073 K and irradiated by helium ions of 30 MeV to various doses in a variable energy cyclotron. The temperature of the sample during irradiation was ~3 5 0 K. Nickel and Ni-0.5% A1 samples were irradiated to a dose of 6 x 10l6 ions/cm2 and Ni-1.0% A1 samples were irradiated to doses of 6 x 1 O I 6 ions/cm2 and 1 x l O I 7 ions/cm2. The helium concentration was estimated to be 95 appm in case of lower dose and z 120 appm for higher dose.The isochronal annealing of the samples was carried out from 353 to 1173 K and the resistivity was measured at liquid nitrogen temperature. The results show that there is a recovery peak at z 483 K in case of Ni-1.0% Al. There is no recovery after this temperature till 873 K from where there is an increase in resistivity till 1123 K and thereafter the resistivity decreases. Fig. 1 shows the isochronal annealing curve of 30 MeV a-ion irradiated pure nickel and Ni-0.5% A1 and Fig. 2 shows the curve for Ni-1.0% Al. It is seen that in these curves, the resistivity starts decreasing nearly up to x523 K with a recovery peak at ~4 8 3 K in case of Ni-1.0% A1 as shown in Fig. 3. After this temperature, the resistivity is practically constant up to a temperature of 873 K from where it shows a negative recovery, i.e. the resistivity increases. The increase in resistivity continues till 1123 K. This temperature is different for Ni, Ni-0.5% Al, and Ni-1.0% Al. After this the resistivity Results and discussion') Bombay 400085, India.

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On the blister formation in copper alloys due to the helium ion implantation

Moreno¹,

Eliezer

²

1997

Metall Mater Trans A

View full text Add to dashboard Cite

A new approach to the blister-formation phenomenon is discussed by means of the mathematical solution on a uniformly loaded circular plate with clamped edges (circular diaphragm). In the present investigation, it was found that blister formation depends on the mechanical properties of the alloys and the near-surface concentration of the implanted gas, which itself is contingent on the crystallographic orientation by means of the stopping power of the implanted atoms. The reported model is based on the fact that at certain depths from the surface, the pressure in the cavities approaches the yield stress of the metal and blistering starts. The thickness of this thin film depends on the mechanical properties of the specific metal. Once a blister cavity is formed, the deformation of the thin film to form a blister cap depends on the buildup of pressure in the cavity contingent on the implanted dose. For the present model, it is sufficient to say that the thickness of the blister's cap cannot be correlated with the projected range of the implantation, as assumed by other authors. The implanted helium concentration needed to buildup enough gas pressure to create a blister at a depth which is close to the projected range is higher by 50 times than the gas helium concentration in the cavity. Experimental results, such as the fact that the blisters have burst at the edge of the circular skin, where the maximum stresses are developed, and the fact that at high implantation energy (large projected range), the bursting of the blisters occurs by multilayer caps, support the present model.

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Surface damage of V-Zr alloy by helium ions

Cited by 5 publications

References 10 publications

On the blister formation in copper alloys due to the helium ion implantation

On the blister formation in copper alloys due to the helium ion implantation

Studies on Helium Ion Irradiated NiAl Alloy

On the blister formation in copper alloys due to the helium ion implantation

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