FP6 priority
1.1.3   Nanotechnologies and Nanosciences, Knowledge-based Multifunctional Materials and New Production Processes and Devices
Title of the proposal

Increase of performance of multiphase nickel-based intermetallics for high temperature structural applications

Slovak Academy of Sciences, Institute of Materials and Machine Mechanics
Racianska 75, 83102 Bratislava, Slovak Republic
Dr. Juraj LAPIN
+421 2 49268290

Research subject for a potential FP6 project

Nickel-based intermetallic alloys represent a group of new advanced materials for high-temperature applications. They are characterised with low density, high melting temperature, ordered structure, resistance to high-temperature oxidation and generally lower price than that of comparable superalloys. Since some properties, mainly brittleness at room temperature and low creep resistance at high temperatures, of single phase intermetallic compounds (Ni3Al and NiAl) are not sufficient for defined structural applications, research is focused on multiphase alloys. The multiphase intermetallic alloys contain two or more phases with considerable different properties. Optimal combination of these phases assures the room-temperature ductility and required high-temperature mechanical properties of these alloys.
One of the aims of recent research is to develop multiphase nickel-based alloys with properties lying between structural ceramic and classical superalloys. However, optimisation of their chemical composition, structure and mechanical properties requires extending fundamental knowledge about these systems.
Directional solidification represents effective method not only to increase ductility and creep rupture life of multiphase intermetallics but allows preparing near net-shaped castings with defined microstructure and crystallographic orientation as well. From the point of fundamental research, it is necessary to elucidate the growth of complex multiphase structures systems and analyse resulting microstructure as a combination of phase transformations during solidification and in solid state during cooling in a defined temperature gradient. In the field of mechanical properties, it is necessary to elucidate micromechanisms governing plastic deformation and effect of coexisting phases on ductility at room temperature. Up to now, it is not sufficiently explored high-temperature creep, fatigue and effect of microstructure on mechanical behaviour.

Recent international cooperation of the research team

Alstom Power, Baden, Stwitzerland; Alstom Power, Finspang, Sweden; IPM, Academy of Sciences of Czech Republic, Czech Republic; University of Northumbria, Newcastle, United Kindgom; Polish Academy of Sciences, Poland; Universite catholique de Louvain, Belgium; IRC, University of Birmingham, Birmingham, United Kindgom; CENIM, Madrid, Spain; CNR-IENI, Milano, Italy; ITC, Povo, Italy; Imperial College, London, United Kingdom; NLR, Nederland

Proposer´s relevant publications related to the research subject

1. LAPIN, J.: High temperature creep of precipitation-strengthened Ni3Al-based alloy. Intermetallics, 7, 1999, pp. 509-609.
2. LAPIN, J. – WIERZBINSKI, S. – PELACHOVA, T.: Microstructural stability, hardness and compressive behaviour of directionally solidified intermetallic Ni3Al-based alloy with \' structure. Intermetallics, 7, 1999, pp. 705-715.
3. LAPIN, J. – PELACHOVA, T. – BAJANA, O.: Microstructure and mechanical properties of a directionally solidified and aged intermetallic Ni-Al-Cr-Ti alloy with \' structure. Intermetallics, 8, 2000, pp. 1417-1427.
4. LAPIN, J.: Development and characterisation of two directionally solidified intermetallic Ni3Al-based alloys. Journal of Materials Science and Technology, 2001, 117, No.3 (Special Issue, CD).
5. LAPIN, J.: Effect of ageing on the microstructure and mechanical behaviour of directionally solidified N3Al-based alloy. Intermetallics, 5, 1997, pp. 615-624.