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Effect of ion implantation on subsequent erosion and wear behavior of solids

Description: The removal of material from a solid surface by mechanical forces is influenced by material properties (hardness, fracture toughness, yield strength, surface free energy) as well as system parameters (force, velocity of loading, environment). Ion implantation can modify many of the material properties either by directly affecting the deformation characteristics or indirectly by affecting the chemical or phase composition at the surface. The various forms of wear and erosion are analyzed to determine the material and system parameters which control material removal. The effects of implantation on these critical parameters are noted and examples of changes in surface topography under various test conditions are discussed. 18 figs.
Date: January 1, 1985
Creator: McHargue, C.J.
Partner: UNT Libraries Government Documents Department

Metals and ceramics division materials science program. Aunnual progress report for period ending June 30, 1979

Description: Progress is reported concerning theoretical studies of metals and alloys, deformation and mechanical properties, physical properties and transport phenomena, radiation effects, and engineering materials. During this period emphasis was shifted from support of nuclear technologies to support of nonnuclear energy systems. (FS)
Date: October 1, 1979
Creator: McHargue, C.J.
Partner: UNT Libraries Government Documents Department

Metals and Ceramics Division materials science annual progress report for period ending June 30, 1977

Description: Progress is reported for research programs in the metals and ceramics division of ORNL. In structure of materials, theoretical research, x-ray diffraction studies, studies of erosion of ceramics, preparation and synthesis of high temperature and special service materials, and studies of stabilities of microphases in high-temperature structural materials. Research into deformation and mechanical properties included physical metallurgy, and grain boundary segregation and embrittlement. Physical properties and transport phenomena were studied and included mechanisms of surface and solid state reactions, and properties of superconducting materials. The radiation effects program, directed at understanding the effects of composition and microstructure on the structure and properties of materials irradiated at elevated temperatures, is also described. (GHT)
Date: September 1, 1977
Creator: McHargue, C.J. (comp.)
Partner: UNT Libraries Government Documents Department

Metals and Ceramics Division materials science annual progress report for period ending June 30, 1978

Description: Topics covered include: structure of materials, theoretical research; x-ray diffraction research; fundamental ceramics studies; preparation and synthesis of high-temperature and special service materials; physical metallurgy; grain boundary segregation and fracture; mechanisms of surface and solid-state reactions; physical properties research; superconducting materials; radiation effects; facility and technique development; nuclear microanalysis; cooperative studies with universities and other research organizations; and fundamentals of welding and joining. (GHT)
Date: September 1, 1978
Creator: McHargue, C.J. & Peterson, S. (comps.)
Partner: UNT Libraries Government Documents Department

Ion-beam mixing of ceramic alloys: preparation and mechanical properties

Description: Techniques used to produce unique states of pure metals mixed into ceramic materials are presented. The samples were prepared by irradiating a 1-MeV Fe/sup +/ beam on Al/sub 2/O/sub 3/ crystal surfaces over which a thin chromium or zirconium film had been evaporated. The limitations of using noble gas ion beams are noted. Micro Knoop hardness tests performed near the surfaces of the samples indicated a significant increase in the hardness of most samples prepared by ion beam mixing.
Date: January 1, 1981
Creator: Lewis, M.B. & McHargue, C.J.
Partner: UNT Libraries Government Documents Department

Surface modification of sapphire by ion implantation

Description: The range of microstructures and properties of sapphire (single crystalline Al{sub 2}O{sub 3}) that are produced by ion implantation are discussed with respect to the implantation parameters of ion species, fluence, irradiation temperature and the orientation of the ion beam relative to crystallographic axes. The microstructure of implanted sapphire may be crystalline with varying concentrations of defects or it may be amorphous perhaps with short-range order. At moderate to high fluences, implanted metallic ions often coalesce into pure metallic colloids and gas ions form bubbles. Many of the implanted microstructural features have been identified from studies using transmission electron microscopy (TEM), optical spectroscopy, Moessbauer spectroscopy, and Rutherford backscattering-channeling. The chemical, mechanical, and physical properties reflect the microstructures.
Date: November 1, 1998
Creator: McHargue, C.J.
Partner: UNT Libraries Government Documents Department

Structural alterations in SiC as a result of Cr/sup +/ and N/sup +/ implantation

Description: Ion scattering and channeling techniques were used to study production of disorder and randomization of SiC by implantation of Cr/sup +/ and N/sup +/ at doses of up to 3 x 10/sup 16/ /cm/sup 2/ for Cr/sup +/ and 8 x 10/sup 16/ /cm/sup 2/ for N/sup +/. Experiments were designed so that the calculated damage energy profiles would be well matched for the two ion species. The results were compared for the degree of effectiveness of Cr/sup +/ and N/sup +/ in producing disorder. At higher doses, Cr/sup +/ was much more effective than N/sup +/ for a given damage energy using the same calculational method for Cr/sup +/ as for N/sup +/. In correlated studies of swelling, both species had about the same effectiveness in producing swelling.
Date: January 1, 1982
Creator: Williams, J.M.; McHargue, C.J. & Appleton, B.R.
Partner: UNT Libraries Government Documents Department

Microstructure and properties of TiB/sub 2/ implanted with 1-MeV nickel

Description: Polycrystalline samples of TiB/sub 2/ were implanted at ambient temperatures with 1-MeV Ni/sup +/ ions to a fluence of 1 x 10/sup 17/ ions/cm/sup 2/. This fluence corresponds to a calculated nickel-to-titanium ratio, within the half width of the ion distribution, of approximately 0.12. Analytical electron microscopy was used to study the resultant microstructure. The starting microstructure was modified to a depth of approximately 750 nm, significantly deeper than the calculated peak in the deposited nickel profile of 389 nm. The results also show a change in the character of the microstructure, from one exhibiting a moderate density of tangled dislocations to a high density of small defects, as well as a change in the concentration of nickel as a function of depth from the implanted surface. There was no evidence of nickel precipitation. Surface mechanical properties such as hardness and wear resistance were significantly increased.
Date: January 1, 1983
Creator: McHargue, C.J.; Sklad, P.S. & Angelini, P. Lewis, M.B.
Partner: UNT Libraries Government Documents Department

Annealing environment effects in solid-phase epitaxial regrowth of Fe-implanted Al/sub 2/O/sub 3/

Description: Samples of c-axis Al/sub 2/O/sub 3/ were implanted with Fe(160 keV,4 /times/ 10/sup 16//cm/sup 2/) at liquid nitrogen temperature and then thermally annealed at temperatures of 900,960 and 1100/degree/C in an oxidising environment (flowing O/sub 2/) or in a reducing environment (flowing 96% Ar, 4% H). Rutherford backscattering spectrometry, ion channeling, and transmission electron microscopy of the crystals revealed differences in the annealing characteristics of the implanted layers that depended on the annealing environment. These results indicate the importance of the annealing atmosphere in determining the characteristics of epitaxially regrown layers in ion-implanted and thermally annealed Al/sub 2/O/sub 3/. 15 refs., 5 figs.
Date: June 1, 1989
Creator: McCallum, J.C.; White, C.W.; Sklad, P.S. & McHargue, C.J.
Partner: UNT Libraries Government Documents Department

Influence of Oxygen Ion Implantation on the Damage and Annealing Kinetics of Iron-Implanted Sapphire

Description: The effects of implanted oxygen on the damage accumulation in sapphire which was previously implanted with iron was studied for (0001) sapphire implanted with iron and then with oxygen. The energies were chosen to give similar projected ranges. One series was implanted with a 1:l ratio (4x10{sup 16} ions/cm{sup 2} each) and another with a ratio of 2:3 (4x10{sup 16} fe{sup +}/cm{sup 2}; 6x10{sup 16} O{sup +}/cm{sup 2}). Retained damage, X, in the Al-sublattice, was compared to that produced by implantation of iron alone. The observed disorder was less for the dual implantations suggesting that implantation of oxygen enhanced dynamic recovery during implantation. Samples were annealed for one hour at 800 and 1200 C in an oxidizing and in a reducing atmosphere. No difference was found in the kinetics of recovery in the Al-sublattice between the two dual implant conditions. However, the rate of recovery was different for each from samples implanted with iron alone.
Date: November 14, 1999
Creator: Hunn, J.D. & McHargue, C.J.
Partner: UNT Libraries Government Documents Department

Surface modification of sapphire for IR window application

Description: Two surface modification techniques, a``super polish`` (SP), and ion implantation, were evaluated for improving the mechanical performance of sapphire IR window material. Both techniques increased the average strength as measured by 4-point bend tests and were effective in preventing the propagation of surface flaws. Ion implantation improved the reliability at lower stresses more than the SP. Neither process significantly affected the IR transmission. The SP produced a smoother surface as shown by optical scatter measurements.
Date: August 1, 1993
Creator: McHargue, C. J. & Snyder, W. B. Jr.
Partner: UNT Libraries Government Documents Department

Ion mixing in oxide-sapphire systems

Description: Ion beam mixing of thin oxide films on sapphire substrates has been studied in order to examine any role of equilibrium thermodynamic parameters on the mixing process. Mixing experiments were performed with polycrystalline oxide films deposited on single crystalline {alpha}-Al{sub 2}O{sub 3} substrates. According to the equilibrium phase diagrams, Cr{sub 2}O{sub 3} is completely soluble in {alpha}-Al{sub 2}O{sub 3}, while ZrO{sub 2} is insoluble. The couples were irradiated with Cr ions (160 and 340 keV) or Kr ions to fluences of 4 {times} 10{sup 16} ions/cm{sup 2} at temperatures between 20 and 900{degrees}C. Rutherford backscattering spectrometry, X-ray photoelectron spectroscopy, and transmission electron microscopy were used to analyze samples before and after irradiation to determine the extent and nature of interface modifications. No long-range mixing was detected under any condition studied; the width of the {open_quotes}mixed{close_quotes} region in each case was consistent with recoil mixing. The absence of long-range mixing is rationalized in terms of the different ranges of oxygen ions and cations.
Date: September 1, 1994
Creator: Joslin, D. L.; White, C. W. & McHargue, C. J.
Partner: UNT Libraries Government Documents Department

Amorphization of sapphire during ion beam mixing

Description: Earlier studies indicated that implantation of zirconium into sapphire at room temperature produced an amorphous layer at a critical composition of approximately 6.5% (cation). Further insight into the amorphization of sapphire has been provided by ion beam mixing studies. Bi-layer couples of {approx}80 nm thick polycrystalline ZrO{sub 2} films deposited on the (0001) face of {alpha}-Al{sub 2}O{sub 3} single crystals were irradiated to 4 {times} 10{sup 16} ions/cm{sup 2} with Kr (475 keV, 20{degree}C), or Cr (340 keV, 20{degree}C or {approx}900{degree}C). Transmission electron microscopy showed the unirradiated couples to have sharp, planar interfaces between the films and substrates. Recoil mixing by both ion species gave Zr concentrations greater than 10% (cation) to depths of 10-20 nm. An amorphous layer containing Zr was present at the interface for samples irradiated at room temperature. The sample mixed at the elevated temperature contained a sharp interface similar to the as-deposited sample. The present results suggest that both irradiation-produced damage (defects) and certain chemical species are required to amorphize sapphire.
Date: September 1, 1994
Creator: Joslin, D. L.; McHargue, C. J.; White, C. W. & Evans, N. D.
Partner: UNT Libraries Government Documents Department

Ion mixing of thin ZrO{sub 2} films on sapphire

Description: Ion beam induced mixing, a process useful in various applications such as adhesion enhancement, involving, metal films on either metal or either metal or oxide substrates has been studied for several years. For this study, analytical electron microscopy (AEM) has been used to investigate ion mixing in an oxide-oxide system: ZrO{sub 2} thin film on {alpha}-Al{sub 2}O{sub 3}.
Date: June 1, 1993
Creator: Evans, N. D.; Joslin, D. L. & McHargue, C. J.
Partner: UNT Libraries Government Documents Department

Hardness of ion implanted ceramics

Description: It has been established that the wear behavior of ceramic materials can be modified through ion implantation. Studies have been done to characterize the effect of implantation on the structure and composition of ceramic surfaces. To understand how these changes affect the wear properties of the ceramic, other mechanical properties must be measured. To accomplish this, a commercially available ultra low load hardness tester has been used to characterize Al/sub 2/O/sub 3/ with different implanted species and doses. The hardness of the base material is compared with the highly damaged crystalline state as well as the amorphous material.
Date: January 1, 1985
Creator: Oliver, W.C.; McHargue, C.J.; Farlow, G.C. & White, C.W.
Partner: UNT Libraries Government Documents Department

Structure of ceramic surfaces modified by ion-beam techniques

Description: A wide variety of structures are produced by ion implantation in ceramics. Random (substitutional and interstitial site occupancy) solid solutions with concentrations of solute that exceed the solubility limit can be produced in Al/sub 2/O/sub 3/. The changes that occur during annealing are complex and sometimes unpredictable. Silicon carbide becomes amorphous in a manner analogous to Si for ion fluences that produce more than 0.2 dpa damage. Light (N) and heavy (Cr) ions produce similar results if the fluence is scaled to damage energy deposited. Because of mass differences in the ions, two damage regions are developed in TiB/sub 2/. The structure remains crystalline to very high damage levels. These structural alterations cause changes in the surface mechanical properties. Since virtually any chemical species can be implanted, one can independently control structural damage and chemical effects. When coupled with selective annealing, this technique has the potential for producing a wide range of surface structures and properties. 8 figures.
Date: January 1, 1982
Creator: McHargue, C.J.; Naramoto, H.; White, C.W.; Williams, J.M.; Appleton, B.R.; Sklad, P.S. et al.
Partner: UNT Libraries Government Documents Department

Amorphization of Ceramics by Ion Beams

Description: The influence of the implantation parameters fluence, substrate temperature, and chemical species on the formation of amorphous phases in Al/sub 2/O/sub 3/ and ..cap alpha..-SiC was studied. At 300/sup 0/K, fluences in excess of 10/sup 17/ ions.cm/sup -2/ were generally required to amorphize Al/sub 2/O/sub 3/; however, implantation of zirconium formed the amorphous phase at a fluence of 4 x 10/sup 16/ Zr.cm/sup -2/. At 77/sup 0/K, the threshold fluence was lowered to about 2 x 10/sup 15/ Cr.cm/sup -2/. Single crystals of ..cap alpha..-SiC were amorphized at 300/sup 0/K by a fluence of 2 x 10/sup 14/ Cr.cm/sup -2/ or 1 x 10/sup 15/ N.cm/sup -2/. Implantation at 1023/sup 0/K did not produce the amorphous phase in SiC. The micro-indentation hardness of the amorphous material was about 60% of that of the crystalline counterpart.
Date: January 1, 1984
Creator: McHargue, C. J.; Farlow, G. C.; White, C. W.; Williams, J. M.; Appleton, B. R. & Naramoto, H.
Partner: UNT Libraries Government Documents Department

The charge state of iron implanted into sapphire

Description: Several techniques (RBS, TEM, CEMS) have been used to characterize sapphire single crystals implanted with iron at room temperature to fluences of 10/sup 16/ to 10/sup 17/ ions cm/sup -2/. At low fluences the as-implanted iron is found mainly in the ferrous state. As the fluence is increased, Fe/sup 3 +/ and metallic iron clusters became dominant. There is a strong correlation between the probability of finding specific configurations of iron ions within four cation coordination shells and the relative amounts of each charge state observed. The superparamagnetic behavior of the clusters suggest that they are of the order of 2 nm in size but the large amount of irradiation-induced damage and residual stress has prevented their imaging by TEM. 13 refs., 7 figs.
Date: August 1, 1987
Creator: McHargue, C.J.; Sklad, P.S.; White, C.W.; Farlow, G.C.; Perez, A.; Kornilios, N. et al.
Partner: UNT Libraries Government Documents Department

Ion beam mixing of chromium or zirconium films with sapphire

Description: Ion beam mixing of thin metallic films deposited on sapphire substrates was studied for chromium or zirconium films deposited on single crystalline {alpha}-Al{sub 2}0{sub 3} substrates. Evidence for the influence of equilibrium thermodynamic factors was sought by comparing the effects of bombarding with oxygen ions (300 and 1073 K) with those of neon ions (300 K). Thermodynamic calculations indicate that mixing might occur for Zr/sapphire at 1073 K but not at 300 K. Chromium/sapphire should not be mixed at either temperature. The implantation energy placed the peak oxygen concentration at the metal/sapphire interface in an attempt to maintain an equilibrium ratio of cations/anions and promote a radiation-induced chemical reaction across the interface. Rutherford backscattering-ion channeling measurements indicated that the widths of ``mixed`` regions were consistent with those predicted from ballistic considerations. Other experiments employed a heavier ion (krypton) as the mixing ion (300 K) in order to increase the mixing efficiency. Rutherford backscattering-ion channeling and x-ray photoelectron spectroscopy were used to determine the extent and nature of any interface modification. XPS results indicated that only metallic chromium (Cr{sup 0}) was present near the interface before and after irradiation with Kr at 300 K. Zirconium exhibited only the metallic state (Zr{sup 0}) in the as-deposited film but was present as both Zr{sup 0} and Zr{sup 4{plus}} after irradiation. Some metallic aluminum (AI{sup O}) was detected near the Zr/sapphire interface, suggesting that a local chemical reaction between Zr and the sapphire occurred during bombardment. No long-range material transport was detected for any experimental condition examined; the width of the ``mixed` region in each case was consistent with that expected for ballistic effects.
Date: December 31, 1995
Creator: McHargue, C.J.; Joslin, D.L.; White, C.W.; daSilva, M.F.; Alves, E. & Soares, J.C.
Partner: UNT Libraries Government Documents Department

Microstructural characterization of iron implanted sapphire nanocomposites

Description: Nanocomposites of iron in sapphire ({alpha}-Al{sub 2}O{sub 3}) prepared by ion implantation have been studied as a model to investigate the potential of such materials for applications in high technology areas. The implantation was performed with 160 keV ions at several doses; the nanocomposites were then annealed at selected temperatures between 700 and 1,400 C in an Ar-4%H{sub 2} atmosphere for 1 hour. Rutherford backscattering spectroscopy and high resolution transmission electron microscopy (TEM) were used to characterize the structure of these nanocomposites. Measurements showed that damage depth extended to about 300 nm and the embedded iron extended to about 200 nm. This region became amorphous when the fluence reaches 2 {times} 10{sup 17} Fe/cm{sup 2} at this energy. Thermal annealing could be used to restore the crystallinity to the damaged near-surface region, to form the metallic colloids, and also to coarsen the precipitates. In the case of high dose implantation, oriented precipitates with diameters of 2 to 3 nm were identified by TEM techniques as {alpha}-Fe which had the following orientation relationship with the sapphire matrix: <111>{sub Fe} {parallel} <310>{sub Sapphire} and {l_brace}01{bar 1}{r_brace}{sub Fe} {parallel} {l_brace}006{r_brace}{sub Sapphire}. The optical density and luminescence spectra were also measured. The predominant defects were oxygen vacancies with two electrons (F center) at the known absorption peak of 200 nm.
Date: December 31, 1994
Creator: Ren, S.X.; McHargue, C.J.; Allard, L.F.; Chen, Y.; Hunn, J.D.; Lucas, B.N. et al.
Partner: UNT Libraries Government Documents Department

Damage accumulation in ceramics during ion implantation

Description: The damage structures of ..cap alpha..-Al/sub 2/O/sub 3/ and ..cap alpha..-SiC were examined as functions of ion implantation parameters using Rutherford backscattering-channeling, analytical electron microscopy, and Raman spectroscopy. Low temperatures or high fluences of cations favor formation of the amorphous state. At 300/sup 0/K, mass of the bombarding species has only a small effect on residual damage, but certain ion species appear to stabilize the damage microstructure and increase the rate of approach to the amorphous state. The type of chemical bonding present in the host lattice is an important factor in determining the residual damage state.
Date: January 1, 1985
Creator: McHargue, C.J.; Farlow, G.C.; Begun, G.M.; Williams, J.M.; White, C.W.; Appleton, B.R. et al.
Partner: UNT Libraries Government Documents Department

Surface modification of sapphire for enhanced infrared window performance

Description: Two ion implantation conditions were evaluated for improving the mechanical performance of sapphire IR window material. Both increased the average strength as measured by 4-point bend tests and were effective in preventing the propagation of surface flaws. Ion implantation that produced a damaged crystalline surface improved the reliability at lower stresses more than the implantation that produced an amorphous surface. Neither process significantly affected the IR transmission.
Date: September 1, 1993
Creator: McHargue, C. J.; Joslin, D. L.; Williams, J. M. & O`Hern, M. E.
Partner: UNT Libraries Government Documents Department