[en] Polycrystalline samples of TiB² were implanted at ambient temperatures with 1-MeV Ni⁺ ions to a fluence of 1 x 10₁₇ ions/cm₂. 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