Heat-resistant intermetallic-based alloys and features of their alloying

Abstract

The work considers the prerequisites for the development of creep-resistant and heat-resistant alloys, based on intermetallics, taking into account the optimal combination of their physical and mechanical properties, as well as structural characteristics. It is shown that there is a sufficient number of intermetallics, which have a density lower than iron-based alloys, which, in combination with high melting temperatures and heat resistance, makes them promising materials for aerospace application, in particular, for gas turbine engine parts manufacturing. The most suitable creep-resistant and heat-resistant intermetallics can be called aluminides and silicides of titanium, nickel and molybdenum. For these compounds, it is possible to combine high values of specific strength with alloying-favorable types of crystal lattice. One of the most important and common creep-resistant alloys based on intermetallics is Ni3Al with FCC lattice. For this material, complex optimized alloying is the main way to increase creep resistance. The heat resistance of such alloys is significantly increased by applying ceramic coatings. Titanium aluminides Ti3Al and TiAl mainly have only a low density among the advantages. Their fragility at room temperatures and tendency to superplasticity at high temperatures significantly limits their application. The impact of disadvantages may be reduced by applying thermomechanical processing of such materials, which aims to change their structure. Alloying titanium aluminides with a large amount of niobium was chosen as a solution that significantly reduced marked week sides of Ti-Al intermetallic alloys. As a result, this led to the creation of a new alloy based on intermetallic Ti2AlNb with a high set of operational characteristics. Mo-Si and Mo-Si-B can be considered as one of the most perfect systems for creating heat-resistant intermetallic alloys. They combine an acceptable density, high creep and heat resistance, which can be additionally increased by reinforcing with ceramic particles. Keywords: intermetallic-based alloys, creep resistance, alloying, Ni-Al, Ti-Al, Mo-Si, Mo-Si-B.