The invention provides compositions and methods for planarizing or polishing a substrate. The composition comprises an abrasive consisting of alumina particles optionally treated with a polymer, an α-hydroxycarboxylic acid, an oxidizing agent that oxidizes at least one metal, polyacrylic acid, optionally, a calcium-containing compound, optionally, a biocide, optionally, a pH adjusting agent, and water. The method uses the composition to chemically-mechanically polish a substrate.