Nickel Ion Implantation Research Articles

Large third-order optical nonlinearity of nanocluster-doped glass formed by ion implantation of copper and nickel in silica

Composite glasses containing different metal nanoclusters were obtained by implanting copper, nickel, or copper+nickel ions in SiO2 glass. The nonlinear refractive index of the composites was determined by the Z-scan method at a wavelength of 770 nm and with a laser pulse duration of 130 fs. Values of n2 up to 0.68 cm2 gW−1 were measured in the case of the Cu+Ni implanted sample.

Amorphization in Al induced by high-energy Ni ion implantation

High-energy nickel ion implantation into pure aluminum targets induces local phase transformations. Samples implanted in a TANDEM accelerator at room temperature were studied by transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS). The TEM observations revealed the presence of spherical amorphous zones. In order to understand this not yet fully explained amorphous phase formation, the mean diameter of the amorphous zones, their numerical density and their amorphous fraction have been determined for samples implanted with different doses. Electron dispersive spectroscopy (EDS) measurements performed on the sample implanted with a dose corresponding to 3.05 at.% Ni have shown that the Ni concentration inside the amorphous zones is about 25 at.%, whereas it is 2.1 at.% in the matrix. Mechanisms explaining the relatively high Ni concentration inside the amorphous zones are discussed.

Electrochemical behavior of titanium implanted with nickel and tantalum ions

Electrochemical behavior of titanium implanted with nickel and tantalum ions and a combination of the two has been investigated as a function of fluences. The polarization curves of the implanted titanium were potentiodynamically measured in the active and passive regions in a boiling 10 wt.% sulfuric acid solution. Electrochemical measurements revealed that nickel ion implantation significantly promoted the passivation of titanium with an increase of fluence and the corrosion potentials resided in the passive region at fluences above 1 × 10 16 ions/cm 2. Tantalum ion implantation was effective in reducing the anodic current densities in the active and passive regions as fluences increased. This effect was reduced at fluences above 7 × 10 16 ions/cm 2. At such fluences, the concentration of the implanted tantalum species decreased due to the etching effect of sputtering. On the other hand, the polarization curves of the co-implanted titanium exhibited more stable passive behavior with considerably low current densities. It was concluded that an excellent corrosion resistance of titanium was achieved by complementary effects of nickel and tantalum ion implantations.

Ni-implanted vitreous electrolyte AgAsS 2: ECR, ionic and electronic conductivity

Transport properties of AgAsS 2 glassy solid electrolyte implanted with 60 keV nickel ions at dose of 10 17 Ni/cm 2 were studied. The increase of ionic conductivity by 2.5 orders of magnitude and simultaneous activation energy decrease from 0.34 to 0.18 eV have been observed. The ionic conductivity enhancement is related to two-phase morphology of implanted layer which leads to formation of “infinite” perculation cluster with low-energy barriers for Ag + ion motion. AgAsS 2 glass reveals p-type electronic conductivity, σ p . Nickel ion implantation increases σ p by six orders of magnitude. The enhancement of hole transport has been explained involving small-polaron hopping between Ni 2+ and Ni 3+ ions. Temperature dependence of Ni 3+ ESR line intensity is in agreement with polaron mechanism of σ p in Ni-containing chalcogenide glasses. ESR results showed also that charge state and coordination of impurity nickel ions in Ni-implanted and thermally-doped AgAsS 2 glasses are identical.

The influence of implanted transition metal ions on the adhesive wear of iron

In a previous study, a model based on the ratio of adhesive to cohesive bonding energy was derived to predict relative wear rates of a variety of metal couples. Surface energy, or reactivity, is a function of the total atomic bonding energy of the atoms comprising the surface and may be varied independently through solid solution alloying. Therefore changes in surface composition should be reflected in the adhesive character and macroscopic wear behavior. Using a reciprocating Be-Cu right cylinder on high purity iron flat as a wear couple, the adhesive character was modified by ion implantation of cobalt, manganese, nickel, niobium, titanium, tungsten and yttrium into the iron flat at a dosage of 1 × 10 17 ions cm −2. The implantation energies were tailored so that the ion concentration vs. depth of penetration below the surface profiles were approximately equivalent. Implantation-induced residual stresses were determined prior to wear testing. The wear-induced surface and subsurface deformation was characterized with microindentation hardness measurements and scanning electron microscopy. A model is presented to explain the enhanced wear resistance of samples implanted with heavier, higher cohesive energy ions compared with those implanted with lighter, lower cohesive energy ions.

Transmission electron microscopy study of amorphization and precipitation in Ni +-implanted aluminium

Implantation of nickel ions into pure aluminium is found to produce either amorphization or precipitation of a cubic phase not predicted by the AlNi phase diagram. Under low ion current ( I ⩽ 1 μA cm −2) and for fluences between 8 × 10 16 Ni + cm −2 and 2 × 10 17 Ni + cm −2 an amorphous phase forms. Under high current ( I ∼ 20 μA cm −2) and for the same fluences a new face-centred cubic (f.c.c.) Al 85Ni 15 precipitate phase is formed in epitaxy with a supersaturated Al 95Ni 5 solid solution. The epitaxial relationship between the precipitates p and the solid solution matrix m is (001) p |(001) m planes, and [040] p z. sfnc; [240] m directions in the planes. The large lattice misfit between the precipitates and the matrix is accommodated by twinning and a tetragonal distortion of the precipitates.

Influence of the implantation of transition metal ions on the electrocatalytic activity of carbon materials

The influence of implantation of titanium, vanadium, chromium iron, cobalt, nickel, zirconium, molybdenum, silver, tungsten, iridium and platinum ions on the catalytic activity of polycrystalline graphite and glassy carbon for the electrochemical hydrogen evolution reaction has been studied. The factors causing an increase of material activity as a result of ion beam modification were determined. Implanted layers were investigated by XPS and voltammetric measurements. The formation of metastable states of implanted transition metal atoms in the carbon matrix has been established. These states are characterized by an unexpected high extent of unoccupancy of d-electronic valence levels. The transition of the implanted system in the equilibrium state occurs by metal atom diffusion and precipitation. Active sites of electronic exchange in the near-surface substrate region are bound to implanted metal atoms or their precipitates. These phenomena result in an increase of adsorptivity and considerable decrease of hydrogen overpotential on modified electrodes.

Elevated temperature microstructural stability of Al +-ion implanted nickel

Composition profiles were measured following 180 keV Al +-ion implantation of nickel at temperatures up to 600°C, and following 600°C annealing of nickel implanted at 25°C. The phases present in the implanted layers were identified and are compared to those found on the NiAl phase diagram. The implanted compositions are nearly temperature independent at fluences below 1.5 × 10 18 ions/cm 2. The Al concentration reaches 70 at.% Al by 3 x 10 18 ions/cm 2 fluence delivered at 25°C, and it extends to 3000Å depth. Beyond 1.5 × 10 18 ions/cm 2 fluence delivered at 500°C, an Al composition of 25% extends to 6000Å depth, well beyond the ~ 100Å increase in depth due to radiation-enhanced diffusion. Similar results obtain for 25°C implanted specimens subsequently annealed at 600°C. TEM examination shows the defect-enriched region beyond 3000Å recrystallizes at elevated temperatures and enhances diffusion via the high diffusivity paths provided by the grain boundaries. Phases found in elevated temperature specimens often differ from those in 25°C implanted specimens. Comparing the former with the latter: Ni 3Al replaces the extended portion of the Al in Ni f.c.c. solution; Ni 3Al and NiAl replace an h.c.p. phase peculiar to lower temperatures; and phases richer than 50% Al are replaced by Ni 3Al due to compositional instabilities. Phase prediction based on local chemical composition and the phase diagram is shown to be valid, but can proceed only when the compositional instabilities are taken into account.

Mechanical property changes in sapphire by nickel ion implantation and their dependence on implantation temperature

Sapphire plates, cut parallel to an {0001} plane, have been implanted with 300 keV nickel ions to doses ranging from 5×1012 to 1×1017 Ni cm−2 at specimen temperatures of 100, 300 and 523 K, in order to investigate the effect of implantation temperature on the mechanical property changes in sapphire caused by ion implantation. The measured changes in surface hardness, surface fracture toughness and bulk flexural strength were found to depend strongly on the implantation temperature, and were largely correlated with the residual surface compressive stress measured by using a cantilever beam technique. The surface amorphization that occurred only by the implantation at 100 K and at doses larger than ∼2×10s15 Ni cm−2 reduced the hardness to ∼0.6 relative to the value of the unimplanted sapphire, and considerably increased the surface plasticity. Furthermore, the amorphization was found to involve a large volume expansion of ∼30% and to change drastically the apparent shape and size of a Knoop indentation flaw made prior to implantation. This effect was suggested to reduce stress concentrations at surface flaws and hence to increase the flexural strength.

Microscopic processes accompanying A1 +-ion implantation of nickel

Nickel substrates have been implanted at room temperature with Al +-ions accelerated through 180 kV, to fluences ranging from 1 × 10 15 ions/cm 2 to 4 × 10 18 ions/cm 2. The composition-versus-depth profiles were determined as were the microstructures in the implanted layers. The implanted concentration reached ~75at.% Al at the highest fluence. Implanted profiles were calculated and compared to the experimentally measured profiles. This showed that the variation in sputtering yield with aluminum concentration controls the increase in aluminum concentration with fluence. Phases observed in the implanted layers included the nickel solid solution with extended aluminum solubility, an h.c.p. phase, β′-NiAl and an amorphous phase. It is suggested that both the h.c.p. and the β'-NiAl phases form martensitically. Neither Ni 2Al 3 nor NiAl 3, found under equilibrium conditions, are observed under implantation. Their replacements by β′ containing 60 at.% Al and an amorphous phase, respectively, result from the radiation damage that accompanies the implantation.

Metallurgical Surfaces Produced by Ion Implantation

Ion implantation, the process of embedding ions accelerated through high voltages, is described as a metallurgical tool for altering surface microstructure and properties. Examples of applications to improve resistance to wear, oxidation, and corrosion are provided. The possibilities for producing surface “superalloys” is explored using Al+ ion implantation into nickel as a prototype alloy system. The micromechanisms which operate and determine implanted surface chemistry are presented, and a predictive capability is demonstrated. Factors determining the phases that are stable in implanted alloys are outlined and demonstrated using P+ and Al+ ion implantation of nickel. Future directions using ion implantation for metallurgical purposes are discussed.

Channelinng and teM studies on Sb + implanted Ni

High dose implantation of the transition metals with group V ions has been shown to yield metamoous metallic alloys. This paper reports one results of a detailed study of Sb + ion implantation of single crystal and polycrystalline nickel. Rutherford backscattering and channeliing together with transmission electron microscopy (TEM) and tranmission and reflection electron diffraction have been employed to measure the type and level of radiation damage, atom location an thhermal annealing of damage for Sb + implantation in the fluence range 10 14 to 10 17 ions cm −2. The susceptibilityof Ni to heavy ion damage has further been examined using molecular Sb 2 + implantations.

Applications of Ion Implantation to Metallic Corrosion

The Bureau of Mines is conducting research on the corrosion behavior of alloys formed by ion implantation with the ultimate goal of conserving strategic alloying materials such as chromium and nickel. These alloys were fabricated by the implantation of 25-keV chromium, nickel, and aluminum ions into polycrystalline iron to fluences ranging from 1 to 5 × 1016 ions/cm2. The alloy distribution as a function of depth (depth profile) has been determined for the ion-implanted alloys, and the results have been compared with theoretical predictions. Changes in the profiles due to annealing were investigated, and the values that were obtained for the diffusion coefficients were compared with published values for the volume diffusion coefficients. The resistance of these alloys to environmental attack has been evaluated both by determining their anodic polarization behavior under potentiostatic conditions in a buffered boric acid solution and by determining their gaseous oxidation characteristics. Results of the electrochemical studies have shown that the general corrosion resistances for the ion-implanted alloys were comparable to those of nominally equivalent bulk alloys and that their pitting corrosion resistance was superior to that of iron, although generally not as good as that for most equivalent bulk alloys. Gaseous oxidation studies have shown that ion-implanted and bulk iron-chromium alloys exhibit essentially identical oxidation kinetics, with a much higher rate of oxidation observed for iron. The influence of radiation damage on the gaseous oxidation of iron has been studied by implanting iron ions into iron.