The Effect of a-Fe Precipitation on the High Temperature Deformation of P NiAl

The microstructures of B2-ordered NiAl containing a-Fe precipitates have been investigated in terms of transmission electron microscopy. Fine precipitation of a-Fe (bcc structure) occurs in NiAl by aging around 973 K. The aging behavior was investigated by microhardness measurements and the temperature dependence of the yield strength of precipitate containing B2-ordered NiAl was investigated by compression tests over the temperature range of 673-1273 K. The fine precipitation of a-Fe was found to enhance greatly the low and intermediate temperature yield strength. When the deformation temperature is over 1073 K, the strength of precipitate containing NiAl was comparable to ternary solid solution hardening NiAl-Fe. Dislocations bypass the particles during deformation and typical Orowan loops were observed surrounding the a-Fe particles after deformation.