THE MECHANICAL RESPONSE OF ALUMINUM IMPLANTED WITH OXYGEN IONS

The microstructure and mechanical properties of high purity aluminum implanted to varying levels of oxygen and subjected to various thermal histories have been examined. Transmission electron microscopy and Rutherford-backscattering spectrometry were used to characterize the depth and nature of the implanted zone: a homogeneous distribution of γ-alumina precipitates with sizes of 5 nm or less extended to a depth of 500 nm below the surface, and the average oxygen concentration ranged up to 20 at.% Ultralow load indentation hardness testing was used to probe the mechanical response of the surface-modified material. The data from the hardness tests were interpreted through the use of a finite-element model; the results indicate the flow stresses of an implanted layer are as high as 1600 MPa. The degree of strengthening expected on the basis of the microstructure was estimated using several micromechanical models, and the results conform semiquantitatively to the findings from indentation testing. © 1990.