High temperature creep of two nanocrystalline alloys

Tensile creep of Ni80P20 and Fe78B13Si9 alloys with grain sizes of 27–28 nm has been studied at temperatures around 0.5 Tm (Tm is the respective melting point). The strain-time relation in the primary creep is found to obey the Andradeʹs law. The stress exponents and activation energies measured in the steady state creep indicate that the creep of both the nano-grained alloys is dominantly controlled by grain (and/or phase) boundary diffusion, while in the creep of coarse-grained samples (250–257 nm) of the two alloys, some additional processes are involved.