Investigation of Mechanical Properties and Elongated Ni Grain Growth in an Al2O3-Ni Composite during Low-Energy Ball Milling

Abstract

A composite of 40 mass% Al2O3-60 mass% Ni was fabricated using powder metallurgy. The composite consisted of Ni powders dispersed in an Al2O3 matrix. The morphology of the Ni powders in the composite was monitored during a low-energy ball-milling process over about 10 h. The shape of the Ni particles changed from spherical to elongated shape using this milling method. The aspect ratio of the elongated Ni grains was measured, and 16% of the total Ni grains in the composite were found to have an aspect ratio higher than 3.0. To investigate changes in mechanical properties due to the elongated Ni powders, strength and hardness were measured. The composite having elongated Ni powders with an aspect ratio higher than 3.0 showed improved strength and hardness compared to the composite containing non-milled particles. Low-energy milling of composites is thus an effective way to control the microstructure of particles in order to improve the mechanical properties of the final composite. Because of its low production cost and simplicity, this method could potentially be used in the production of various reinforced composites. [doi:10.2320/matertrans.M2011196]