The effects of titanium ion implantation on structural and mechanical properties of single crystal and polycrystalline α-alumina were studied. Grazing angle X-ray diffraction (GXRD) allowed the identification of structural alterations. Surface morphology was observed directly using scanning electron microscopy (SEM), elastic and plastic properties of the implanted layers (of which the thickness is about 100nm) have been characterised by microprobe investigation. Results of the hardness and Young’s modulus, determined by nanoindentation technique and the physicochemical study, have allowed us to correlate elastic and plastic property modifications with microstructure state of implanted ceramics and after annealing. Ion implantation plus thermal annealing were found to be favourable for the improvement of mechanical properties.

In ion implantation, the interaction between the ions and target atoms result in modifications to the crystallographic structure of the implanted substrate. The chemical nature of the implanted ion can in certain cases, if thermal treatments after implantation are done, produce a chemical composite of two oxides types. The crystallographic modifications can produce an enhancement of the surface mechanical properties. Polycrystalline alumina was implanted with Ti or Cr ions at 110 keV and heat treated at a series of temperatures. We have examined the resulting implanted layers by the following analysis techniques: Secondary Ion Mass Spectroscopy (SIMS), to obtain the as-implanted profiles, Scanning Electron Microscopy (SEM), for investigation the chemical composite formation on the surface, and finally grazing incidence X-ray diffraction (GXRD), for determination of the crystallographic nature of the precipitates. By the Vickers indentation method, using different loads we determined the hardness and the fracture toughness of the implanted layer. The residual surface compressive stresses produced by these implantations, were measured by the Lawn and Fuller [1] technique.

Nanoindentor techniques have been used to obtain the values of hardness and elastic modulus of α-Al2O3 polycrystalline implanted with metallic species at room temperature with 170 keV, doses ranging from 2×1016 to 2×1017 ions cm-2. After implantation, annealing was performed in the temperature range 600–1400°C. An attempt has been made to correlate the mechanical property modifications with physico-chemical analysis. Elastic and plastic properties of the implanted layers, of about 100 nm thickness, have been characterized by microprobe investigation. This has indicated that certain fluences and thermal annealing temperatures are favourable for the improvement of mechanical properties.

Mechanical properties of ion implanted ceramics are connected with the microstructure and the residual stresses introduced by implantation. In this work, studies on the implantation of chromium and titanium in alumina are reported. The residual surface compressive stress has been determined using an indentation technique, based on the method of Lawn and Fuller which deduces stress from the size of cracks around Vickers hardness indentation. The measurement of the mechanical properties, i.e. fracture toughness, in the treated surface, was undertaken using a Vickers indentation method. Finally, these implantations have been investigated by means of SEM and SIMS to study the eventual formation of chemical compounds in the implanted zone. For the two ions implantation, the increase of KIC has been attributed to the compressive stresses. After heating, relaxation of residual stresses occurs in the two cases and TiO2 formation in the case of titanium implantation. The oxide formation increases the fracture toughness by a compensation of the residual stresses relaxation. For chromium implantation the relaxation decreases the toughness.

The effect of copper implantation on the mechanical properties, such as hardness, fracture toughness, and residual stress of alumina is addressed herein. The implantation conditions are conducted at room temperature on the polycrystalline alumina with doses ranged from 3 x 10(16) to 10(17) Cu cm(-2) (110 keV). The ion profile distribution was examined by Rutherford backscattering spectroscopy. Surface morphology was observed directly using scanning electron microscopy. Using the X-ray diffraction, we determined the crystallographic nature of the precipitates formed after heat treatment, The residual surface compressive stresses produced by these implantations, as determined by an indentation technique, ranged from 950 to 1720 MPa. Implantation caused a modification in the mechanical properties and an increase in the residual stress. The average residual compressive stress in the implanted region increases with fluence. (C) 1997 Elsevier Science S.A.

Ion implantation is known to be capable of modifying the surface and near-surface chemical and mechanical properties of solids pertaining to hardness, elastic modulus and fracture toughness. In this study polycrystalline alumina was implanted with and ions (110 keV) to a dose of at room temperature. Mechanical properties such as hardness and Young's modulus were determined using an ultra-low load microindentation hardness tester. With the Vickers indentation method, using different loads, the fracture toughness of the implanted layer was determined. The nature of the chemical phases were characterized by x-ray photoelectron spectroscopy (XPS). Implantation caused an increase in the hardness and the fracture toughness with no detectable effect on the Young's modulus. These modifications were attributed to microstructural changes caused by the implantation. The residual stresses were determined by a previously described indentation technique. They were found to be compressive in nature and ranged from 800 to 1800 MPa.

Polycrystalline tetragonal zirconia was implanted with 170 keV Ti ions to doses of 2 x 10(16) ions/cm(2) and 1 x 10(17) ions/cm(2). Localised plasticity, elasticity and fracture behavior have been investigated using nanohardness and microhardness indentation tests. Significant surface hardening has been observed at lower and higher doses. Post-implantation heat treatments produce precipitation reactions with associated hardness and elastic modulus changes, and reduced the fracture toughness at 1200 degrees C to pre-implant levels.

A study of ion implantation in polycrystalline alumina has been undertaken aimed at two principal areas. Firstly the measurement of the evolution of mechanical properties in the treated surface, such as hardness and fracture toughness, was undertaken using a Vickers indentation method. These properties are very sensitive to the presence of residual stresses and to the surface microstructure. Secondly a physicochemical study of the treated surface using XRD and SEM techniques in order to identify the parameters that influence the mechanical changes was undertaken.