The effect of grain size of magnesia and its content as well as spark plasma sintering conditions on the density, grain size, strength, hardness, and toughness of alumina was investigated. Spark plasma sintering conditions were optimized at 1150°C/5 min/175°C/min. Addition of 100 nm magnesia gave higher density levels (99.5%), while better strength (600 MPa), hardness (25 GPa), and fracture toughness (4.5 MPa·m1/2) were obtained with 15 nm magnesia. The good strength and hardness is attributed to the submicrometer grain size of the matrix, and the improved toughness to the presence of Mg-rich nanoparticles and nanopores at grain boundaries.
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Document Type: Research Article
International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), Hyderabad 500005, Andhra Pradesh, India
Defence Metallurgical Research Laboratory, Hyderabad 500058, Andhra Pradesh, India
Publication date: January 1, 2008