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Fine Ti‐dispersed Al 2 O 3 composites and their mechanical and electrical properties
Author(s) -
Shi Shengfang,
Cho Sunghun,
Goto Tomoyo,
Sekino Tohru
Publication year - 2018
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.15472
Subject(s) - materials science , composite material , flexural strength , fracture toughness , percolation threshold , sintering , intermetallic , transgranular fracture , electrical resistivity and conductivity , composite number , titanium , hot pressing , metal , intergranular fracture , intergranular corrosion , microstructure , metallurgy , engineering , alloy , electrical engineering
Abstract Al 2 O 3 /Ti composites containing 0‐30 vol% dispersed fine Ti particles were fabricated using a hot‐press sintering method at 1500°C from mixtures of Al 2 O 3 and TiH 2 powders. During sintering, TiH 2 decomposed to form metallic Ti. The effects of the Ti content on the mechanical and electrical properties of the composites were then investigated. No Ti‐Al intermetallic compounds were detected by X‐ray diffraction, and energy‐dispersive X‐ray spectroscopy indicated the presence of Al‐Ti‐O solid solution and Ti‐O phases. The composites showed enhanced densification; the measured densities were higher than the calculated theoretical values. Microstructural observation revealed homogeneously distributed fine Ti particles dispersed in the Al 2 O 3 matrix. The Ti particle size ranged from submicrometer to a few micrometers depending on the Ti content. The fracture mode of the composites was primarily transgranular, in contrast to the intergranular fracture mode of monolithic Al 2 O 3 . Although the flexural strength was decreased with increase in Ti content, the composite containing 20 vol% Ti displayed the maximum fracture toughness of 4.3 MPa·cm 1/2 , which was 37% greater than that of monolithic Al 2 O 3 . The composites containing more than 15 vol% Ti exhibited drastic decreases in resistivity (~10 −1 Ωcm), which were attributed to the formation of interconnected Ti networks at these Ti contents. The percolation threshold volume for electrical conduction in the present system was calculated to be 13.8 vol%. The results indicate that dispersing fine Ti particles into Al 2 O 3 increased the fracture toughness and improved the conductivity of Al 2 O 3 .