Investigation of instability of M23C6 particles in F82H steel under electron and ion irradiation conditions

Dissolution of M23C6 and New Phase Re-Precipitation in Fe Ion-Irradiated RAFM Steel

“…Irradiation can increase the diffusion rates through the production of point defects, which can be trapped by the interface between M 23 C 6 precipitates and matrices. In-situ observations revealed that the small M 23 C 6 fragment can separate from the pre-existing M 23 C 6 precipitates in 2-MV electron irradiated F82H steel [32]. The irradiation-induced phase transformations are possible because the free energies of the different phases are changed by the excess energy introduced into the lattice.…”

APT characterization of irradiation effects on MX phase in reduced-activation ferritic/martensitic steels

“…In this case, N could play an important role in the formation of these ions, as the lack of N in the VC phase of F82H prevents the formation of Ta x C y N z H h n + ions. It has also been proven that the addition of nitrogen in pure tantalum changes the prevailing microscopic diffusion mechanism of H [34] . Many researchers found that the additional nitrogen decreases the diffusivity of hydrogen [34] and contributes to hydrogen trapping with a small trapping enthalpy in tantalum [35] .…”

“…It has also been proven that the addition of nitrogen in pure tantalum changes the prevailing microscopic diffusion mechanism of H [34] . Many researchers found that the additional nitrogen decreases the diffusivity of hydrogen [34] and contributes to hydrogen trapping with a small trapping enthalpy in tantalum [35] . In the nitride, the high concentration of hydrogen with Ta x C y N z H h n + forms indicates some special connection among Ta, N, C and H in the MX nanoprecipitate.…”

“…In these materials, irradiation can induced the nano-sized cluster formation [ 1 , 2 , 7 , 12-18 ] and grain boundary segregation [ 3 , 6 , 13 , 14 , 18 ]. ied under irradiation in both the conventional FM steels and the RAFM steels [26][27][28][29][30][31][32][33][34][35][36] . M 23 C 6 endures amorphization at low irradiation temperatures [ 26 , 27 , 29-32 ] and coarsening at high irradiation temperatures [28] .…”

Predicting carbon diffusion in cementite from first principles

“…The stability of carbides is reduced by irradiation. Experimental studies report the precipitation of new carbide phases around pre-existing carbides under ion irradiation or high temperature neutron irradiation [1,3], as well as the dissolution [1,4] and the amorphisation of pre-existing carbide phases under ion irradiation [1]. Yet, it is difficult to provide a quantitative explanation of these observations in out-of-equilibrium conditions since the equilibrium thermodynamic and diffusion properties of carbides are still poorly known.…”