No abstract

The effect of pulsed plasma flow treatment on the structural phase state (SPS) and the strength ening of near surface layers of fuel claddings of chromium ferritic-martensitic steels is investigated. The modification of cladding sections is performed by helium and nitrogen plasma flows with a specific power varying in the range of 0.6-5.2 MW/cm 2 at a pulse duration of ~15-20 μs. The number of irradiation pulses N is varied from 2 to 10. It is found that the treatment of claddings by plasma flows with a specific power of ~1.0 MW/cm 2 (N = 2) results in surface melting. The solidification of near surface layers forms a two dimen sional nanocrystalline structure with a lateral dimension of grains of ~100 nm. It is revealed that the plasma treatment results in a change in the crystallographic texture of surface layers of claddings, causing the growth of texture component {100} along the radial direction of claddings, and in a decrease in the lattice parameter determined by the orientation of source grains. It is shown that the occurring structural phase changes result in the surface strengthening of claddings up to 50%, whose degree depends on plasma treatment conditions.