Mechanical Properties of TiAl-type P/M Intermetallics at Elevated Temperatures.

概要

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TiAl P/M intermetallics bearing Si ≤ 3.1%, B ≤ 0.12% and Nb ≤ 13.3% were surveyed in respect of mechanical and oxidation behavior in the range: 600-1 200°C. The oxidation resistance of TiAl alloy is appreciably improved by Si and/or Nb addition, probably due to the protective aluminum-rich oxide on surface. Siliconizing instead of Si alloying will be recommended for good mechanical properties. In general, the tensile strength has a peak value of more than 350 MPa at 800°C or so nearly corresponding to brittle-ductile transition. The creep-rupture strength of TiAl alloy is more or less improved by Nb addition. Consequently, TiAl alloy bearing 1.5% Si and 3-6% Nb will be preferable for use in hot air up to 900°C. A further survey on superplasticity is required for alloy design and microstructural control.
The Iron and Steel Institute of Japanの論文