Plasticity improvement of Fe-13Cr-6Al-2Mo-0.5Nb alloy with yttrium addition by hindering Laves phase precipitation

The microstructures and mechanical properties of Y-free and Y-containing (0.1Y) Fe-13Cr-6Al-2Mo-0.5Nb alloys during isothermal long-term aging at 475 degrees C for 10,000 h were investigated. Distinct from the aged Y-free Fe13Cr-6Al-2Mo-0.5Nb alloy, of which the Laves phases with a mean size of similar to 100 nm precipitated along the grain/subgrain boundaries, a large number of uniformly distributed nanoscale L2(1)-ordered Fe-2(Mo0.3Nb0.7)Al phases and a few fine Laves phases were observed in the aged Y-containing (0.1Y) Fe-13Cr-6Al-2Mo-0.5Nb alloy. The addition of yttrium hindered the precipitation of the Laves phases by reducing the diffusion ability of the alloy atoms, thus leading to the plasticity improvement of the Fe-13Cr-6Al-2Mo-0.5Nb alloy for fuel cladding under operating conditions.