HEMI Seminar: Dipankar Banerjee, Indian Institute of Science Bangalore

Novel High Temperature, High Strength Eutectic Intermetallics

Dipankar Banerjee

Department of Materials Engineering, Indian Institute of Science Bangalore, India

We describe a new class of superalloys based upon combinations of intermetallics as fine scale eutectic structures in the Ni-Al-Zr system. The microstructural stability of the as-cast material as function of long term thermal exposure is examined. Tensile and compressive properties as function of strain rate and temperature and microstructural length scales has been evaluated. The alloys show extremely high strength approaching 2 GPa up to temperatures of 700C with tensile ductility between 3-4 % at room temperature. Plastic deformation processes at room temperature have been examined samples and related to fracture processes in the alloys. Preliminary creep studies are reported. We have also examined the oxidation behaviour of these alloys under isothermal and thermal cycling at temperatures exceeding 900C.