日本金属学会誌

J. Japan Inst. Metals, Vol. 61, No. 6 (1997),
pp. 544-552

Enhanced Solid State Reaction of TiO2/Al Composites by Doping

Isao Tsuchitori1, Gen Sasaki2 and Hideharu Fukunaga2

1Industrial Research Institute West of Hiroshima Prefecture, Kure 737
2Cluster 1, Faculty of Engineering, Hiroshima University, Higashi-Hiroshima 724

Abstract:

Rutile-type TiO2/Al composites have hardenability due to the reaction between components by heat treatment in the solid state. It has been found that the reaction on the solid state is induced by impurity element in reinforcement such as Na, and the hardenability is considered practically useful. In the present work, for the purpose of defining the role of impurity on the reaction and of seeking for effective other impurities, the reactivities of various kinds of TiO2/Al composites were examined by DSC and their reaction mechanisms were investigated. The composites were fabricated from pure Al and TiO2 particles which were doped with small amounts of alkali or alkali-earth metal oxides. When the TiO2 powder was doped with Na, K, Rb, Cs, Ca, Sr and Ba, the TiO2/Al composites revealed an exothermic peak in the DSC curve at about 873 K. But the peak by the reaction in the solid state could not be observed in the case of the dopants of Li, Be and Mg. It was also found that the exothermic peak of the composites in the solid state was higher with increasing ionic radius of the dopants. It can be fairly certain that the dopant which induces the reaction forms an oxide complex on the surface of TiO2, but not diffuses into TiO2. From the experimental results, it can be considered that the oxide complex plays the role of a diffusion path of the Al ion to promote the reaction between TiO2 and Al. The reaction mechanism of the composites in the solid state is explained by the formation of the oxide complex and the crystalline structure, which is produced on the surface of TiO2 powder as alkali or alkali-earth metal oxides and by the diffusion behavior of the Al ion through the oxide complex and into the TiO2 particle.


(Received February 17, 1997)

Keywords:

titanium dioxide, rutile, aluminum alloy, metal matrix composites, reaction hardening, doping, heat treatment, reaction mechanism


PDF(Free)PDF (Free)     Table of ContentsTable of Contents

Please do not copy without permission.