J. Phys. IV France 112 (2003) 1067
Martensitic transformation and ordering in heat-resistant Ni-Co-Cr-AI / eutecticsS.V. Kositsyn1, N.V. Katayeva1, I.I. Kositsyna1, A.I. Valiullin1 and V.S. Litvinov2
1 Institute of Metal Physics, Ural Branch RAS, Laboratory of Mechanical Properties, 18 S. Kovalevskaya Str., Ekaterinburg 620219, Russia
2 Ural State Technical University, 2 Mir Str., Ekaterinburg 620002, Russia
The method of thin-foil transmission electron microscopy was used to examine phase transformations in the -phase, representing the main heat-resistant component, of / eutectics of the Ni-Co-Cr-Al system (mass % : 0-15 Co, 14-20 Cr, 8.5-10.5 Al). The martensitic transformation took place in all the alloys, except those with 20 mass % Cr, when they were quenched in water from 1200°C. It was found for the first time that high-rank superstructures A 2B (Ni 2Al) and A 5B 3 (Ni 5Al 3) could be formed in a complex-alloyed solid solution. Phase transformations L1 , , , and were observed in the -component of the eutectics when isothennal annealing temperature was increased from 250 to 600°C. At a temperature of 400°C and higher those transformations were accompanied by the decomposition of the solid solution and the appearance of dispersed -Cr particles. Structural features of the aforementioned phase transformations in heat-resistant quaternary eutectics were considered.
© EDP Sciences 2003