Carbon in Nb-rich γ-TiAl based alloys
Intermetallic γ-TiAl based alloys are light-weight high-temperature structural materials of great technological interest. They have the potential to partly replace the heavier Ni based super alloys for applications as compressor and turbine blades in gas turbines and aero engines [1]. TiAl alloys are two-phase alloys consisting of tetragonal γ-TiAl and small amounts of hexagonal α2-Ti3Al. In order to extend their service range to higher temperatures research activities have been focused on high Nb bearing TiAl alloys. These so-called third generation or TNB alloys exhibit a significant increase in strength combined with improved creep properties and oxidation resistance [2].
The characteristics of TiAl-based alloys melted in graphite crucibles
ABSTRACT In the paper, the phase composition, microstructure, and selected mechanical and operational properties at room and elevated temperature of a TiAl intermetallic alloy from the TNB group – Ti–45Al–8Nb–0.5(B, C), induction melted in special graphite crucibles, are characterised. Selected properties of this alloy were compared to those of the reference TNB-V2 alloy with similar chemical composition, prepared with technologies currently used in the world. The result of this comparison was a positive recommendation for the proposed melting technology as an alternative to this and other groups of TiAl-based alloys. This paper is part of a thematic issue on Titanium.
Heat Transfer Characteristic for a New Plate Metal Hydride Reactor
The property of major metal hydride reactors in the world was analyzed and a new plate metal hydride reactor was designed.An experimental facility to test the metal hydride reactor was also designed correspondingly.The effective thermal conductivity of the plate metal hydride reactor was measured by varying the initial metal hydride packing fraction,the kind of filled gas and the pressure of the filled gas,cycle numbers.The test results show that the effective thermal conductivity of the reactor,has exceeded(7.5) W/(m·K) before activation,which is increased greatly.After alloy activation,the effective thermal conductivity of the reactor has a linear change trend with the hydrogen pressure during the interval 0.1~3.5 MPa.The effective thermal conductivity of the reactor just only decreases quickly at the beginning,but becomes stable after several cycles.