Effects of solute atoms on evolution of vacancy defects in electron-irradiated Fe–Cr-based alloys

Equilibrium Vacancy Concentration Driven by Undetectable Impurities

“…The results will be easily included in the analytical expressions derived in this Letter. These expressions are straightforward to apply in other relevant materials, e.g., transition metals rare earth oxides [60], AlZr [61]), ZrNb [62], FeCr [63], or NiC [64][65][66]. A striking feature highlighted in this Letter which should occur in many systems is the nonlinearities of the effective vacancy formation free enthalpy, within temperature ranges for which it is conventionally admitted that an Arrhenius law is valid.…”

Mössbauer Analysis of Deformation–Induced Acceleration of Short-Range Concentration Separation in Fe-Cr Alloys—Effect of the Substitution Impurity: Sb and Au

“…The doping with the impurities Sb and Au, preserving a qualitatively general form of the dependence of c1,2 on the HPT temperature, shifts the border between the first and the second regions of temperatures by ~250 K and by ~100 K in the alloys with Sb and with Au, respectively, in relation towards that typical of the binary alloy Fe-16Cr. To elucidate the mechanism of the effect of a substitution impurity on the deformation-induced process of SR ordering, in the present investigation we have made a comparison between our results and PAS data [11] on the evolution of vacancy defects in alloys of similar compositions, see Figure 6. Positrons are a sensitive indication of the start of stabilization of defects of vacancy type [23].…”

“…The concentrations of Sb and Au were controlled by weighting and confirmed by the methods of Rutherford backscattering and X-ray microanalysis. For a more correct comparison of Mössbauer and PAS data, the investigations were performed on the same samples [11]. The procedure of preparation of alloys is described in [13].…”

“…In the experiments with employment of positron-annihilation spectroscopy (PAS), the stability of vacancy complexes was determined based on the knowledge of the temperature of their dissociation from the curves of the parameter S versus temperature of heating. In the case of the alloys Fe-16Cr doped with Sb and Au, the onset (in case of each impurity) of dissociation of vacancy-impurity complexes formed as a result of irradiation with a fluence of F = 5 × 10 21 m −2 were found to have shifted into the range of higher temperatures by 250 and 100 K, respectively [11]. Since the substitution impurities essentially weaken the mobility of vacancies in irradiated samples, it is of interest to investigate the effect of these impurities on the mechanism and kinetics of the deformation-induced SRO connected with the mobility of vacancy complexes [6].…”

“…It is known that in iron and in Fe-Cr alloys, oversized impurities of substitution, such as Sb and Au, in conditions of irradiation just form vacancy complexes stable at a thermal annealing [11,12]. In the experiments with employment of positron-annihilation spectroscopy (PAS), the stability of vacancy complexes was determined based on the knowledge of the temperature of their dissociation from the curves of the parameter S versus temperature of heating.…”