A chemical mechanical polishing composition for polishing a substrate includes a liquid carrier and cationic metal oxide abrasive particles dispersed in the liquid carrier. The cationic metal oxide abrasive particles have a surface modified with at least one compound consisting of a silyl group having at least one quaternary ammonium group. A method for chemical mechanical polishing a substrate including a metal layer includes contacting the substrate with the above described polishing composition, moving the polishing composition relative to the substrate, and abrading the substrate to remove a portion of the metal layer from the substrate and thereby polish the substrate.