| Abstract Scope |
Refractory alloys represent candidate structural materials for nuclear reactors. In this work atomistic simulations were employed to study the thermomechanical behavior of two representative binary refractory systems. The influence of composition and elemental segregation on the behavior of ½<111> screw dislocations was investigated in W-Mo alloys. The computed dislocation velocities showed dislocation mobility regimes governed by kink-pair formation and phonon drag. The alloy containing 50 at% W had the lowest kink-pair formation energy, consistent with its higher dislocation velocity. Molybdenum segregation to the dislocation was thermodynamically favorable and significantly delayed the onset of dislocation glide. A segregation/de-segregation phase transition occurred at 2500 K. Next, an interatomic potential for the Nb-Cr system was developed and used to examine the behavior of solid solutions. Mechanical strength, heat capacities, thermal expansion coefficients, and thermal conductivities were found to decrease with Cr content. Finally, the thermodynamic stability of various Laves phases was analyzed. |