Microstructure evolution of Ni3Al-based alloy, during different stages of plastic deformation was investigated by conventional transmission electron microscopy. Significant grain refinement was observed. The finest grains (100 nm) were even hundred times smaller than the initial ones (10 mum). Various aspects of strengthening mechanisms were indicated: deformation and solid solution strengthening, hardening due to antiphase boundaries formation and martensitic transformation of the NiAl interdendritic phase. (C) 2003 Published by Elsevier Science B.V.