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.
Google Earth: Mathematical Art Forms
We trace the development of Google Earth and consider various artifacts, natural and anthropogenic, ancient and modern. These artifacts are only obvious from high elevations and some have a mathematical form and artistic appeal. We also illustrate how Google Earth's high-altitude imagery can be fruitful inspiration for mathart and provide some example.