B.M. Pande

Diffusion of chromium and iron in Zircaloy-2

Abstract Using the residual activity method, the diffusion of chromium and iron in alpha and beta Zircaloy-2 has been studied in the temperature range of 650–1250 °C. The temperature dependence of their diffusivities (in cm 2 /sec) can be described as D Cr / α Zircaloy -2 (650–780 ° C ) = 2.91 × 10 −6 exp (−35 620 cal / RT ), D Cr / gb Zircaloy -2 (980–1250 ° C ) = 6.31 × 10 −2 exp (−51 040 cal / RT ) and D Fe / α Zircaloy -2 (650–780 ° C ) = 2.56 × 10 −8 exp (−27 110 cal / RT ), D Fe / β Zircaloy -2 (980–1250 ° C ) = 1.03 × 10 −2 exp (−46 767 cal / RT ). A non-linearity in the Arrhenius plots has been observed in the phase transition region (780–960 °C). It has been explained on the basis of the statistical average of the diffusivity in both the phases present at a particular temperature in the transition region.

Diffusion of nickel and tin in zircaloy-2

Abstract The diffusion of nickel and tin in alpha and beta zircaloy-2 has been studied by the residual activity technique in the temperature range 650–1250 °C. The temperature dependence of diffusivities (cm 2 /sec) can be expressed as D Sn /α-zircaloy-2 (650–780 °C) = (3.31 ±0.56) × 10 −6 exp( −36.630±377 RT) D Sn /β-zircaloy-2 (980–1250 °C) = (2.80 ±0.56) × 10 −1 exp( −55.905±809 RT) and D Ni /α-zircaloy-2 (650–780 °C) = (1.00 ±0.17) × 10 −7 exp( −29.339±296 RT) D Ni /β-zircaloy-2 (980–1250 °C) = (7.30 ±1.16) × 10 −3 exp( −47.960±587 RT) . The results have been explained on the basis of alloying characteristics of zircaloy-2 and it is noticed that with the exception of tin, the small percentage of other constituents in zircaloy-2 does not affect the diffusion properties.

Surface damage of V-Zr alloy by helium ions

Abstract Helium ion irradiation of V-2 wt% Zr alloy was carried out at various energies in the MeV range. Blisters and exfoliations were observed using SEM at higher doses. SIMS analysis was used to estimate qualitatively the retention of helium after annealing at 700 K. Hardness measurements were carried out on the bombarded area to determine the effects of retained gases on mechanical properties.

Low temperature (4.6 K) fast neutron irradiation of zirconium and zircaloys 2 and 4: Dose and recovery studies

Abstract Zirconium Ziicaloy-2 and Zircaloy-4 were irradiated with fast neutrons to a fluence of 1 × 10 22 n / m 2 at 4.6 K. Dose curves [ d ( Δp )/ d (∅ t ) versus Δp ] were plotted for all the materials. Isochronal annealing of these irradiated materials was carried out from 18 to 323 K, showing defect peaks at 110–120 K and 235–237 K. Migration energy E M was determined for stage III and was 0.28 eV for zirconium and 0.35 eV for Zircaloy-2. An attempt has been made to explain these results.

Characterization and deuterium ion bombardment behaviour of titanium carbide coatings

Titanium carbide has been deposited on 304 and 316 stainless steel, Monel 400, molybdenum, copper and graphite employing electron beam evaporation technique. The coatings were characterized using AES, ESCA, RBS, SIMS and SEM. Its elemental analysis shows the presence of titanium, carbon and oxygen, with carbon being in the carbide form. Thermal cycling and fatigue testing of coatings showed its capability to withstand 4700 laser pulses of 2 KW/cm2 and 19 ms duration without any visible change. These coatings have been bombarded at energies of 40 and 80 keV with doses of 5 × 1020, and 2.65 × 1020 and 6.2 × 1020 ions/cm2, respectively, using an unanalysed deuterium beam. In general, the bombardment has resulted in a decrease in the C/Ti atomic ratio, thereby changing the film composition. In particular, exfoliations and formation of TiD has been observed.

Fast neutron irradiation of A-203 steel — recovery studies

Abstract A-203 steel has been irradiated by fast neutrons to fluences of 1 × 10 22 and 1.25 × 10 22 n / m 2 . The isochronal annealing studies have been carried out from 333 to 913 K. The results show a recovery peak at ~ 385 K, which has been explained to arise due to migration of carbon and carbon-vacancy complexes. After this stage the resistivity instead of decreasing starts increasing. This has been explained on the basis of increase of short range ordering on annealing. The influence of nickel and carbon on the recovery behaviour has also been discussed.

Interaction of oxygen with radiation-induced defects in dilute vanadium alloys

Abstract Isochronal annealing studies of both cold-worked and neutron-irradiated vanadium, vanadium-2 at.% niobium and vanadium-2 at.% aluminium alloy, were carried out. A stage was observed for all the materials at ~430 K. Recovery in vanadium-2 at.% aluminium was comparatively less than pure vanadium or vanadium-2 at.% niobium. Results indicate that oxygen is the migrating specie in this stage.

Deuterium ion bombardment of D.C.-sputtered carbon coatings

Abstract Carbon coatings prepared by d.c. sputtering on 304 stainless steel were bombarded by deuterium ions at the following energies and doses: 20 keV, 3.2×1020 ions cm-2; 40 keV, 8.4×1019 ions cm-2; 80 keV, 6.5×1020 ions cm-2; 120 keV, 9.3×1020 ions cm-2. These coatings, on bombardment with 40 and 120 keV deuterium ions showed blister formation whereas sputter etching was the predominant feature observed for 20 and 80 keV ions. The bombardment seems to have brought about changes in the surface activity of the coating (i.e. its adsorption and desorption characteristics for ambient gases).