An Evaluation of the Fe-N Phase Diagram Considering Long-Range Order of N Atoms in γ'-Fe4N1-x and ε-Fe2N1-z

The chemical potential of nitrogen was described as a function of nitrogen content for the Fe-N phases α-Fe[N], γ'-Fe4N1-x, and ε-Fe2N1-z. For α-Fe[N], an ideal, random distribution of the nitrogen atoms over the octahedral interstices of the bcc iron lattice was assumed; for γ'-Fe4N1-x and ε-Fe2N1-z, the occurrence of a long-range ordered distribution of the nitrogen atoms over the octahedral interstices of the close packed iron sublattices (fcc and hcp, respectively) was taken into account. The theoretical expressions were fitted to nitrogen-absorption isotherm data for the three Fe-N phases. The α/α + γ', α + γ'/γ', γ'/γ' + ε, and γ' + ε/ε phase boundaries in the Fe-N phase diagram were calculated from combining the quantitative descriptions for the absorption isotherms with the known composition of NH3/H2 gas mixtures in equilibrium with coexisting α and γ' phases and in equilibrium with coexisting γ' and ε phases. Comparison of the present phase boundaries with experimental data and previously calculated phase boundaries showed a major improvement as compared to the previously calculated Fe-N phase diagrams, where long-range order for the nitrogen atoms in the γ' and ε phases was not accounted for

LATENT HEAT STUDIES OF MAGNETIC TRANSITIONS IN DILUTE CrFe AND CrSi ALLOYS

La constitution du diagramme des phases magnétiques CrFe et CrSi dilué et l'ordre des transitions ont été étudiés par des mesures calorimétriquesThe constitution of the magnetic phase diagrams for dilute CrFe and CrSi and the order of the transitions have been investigated by calorimetric measurements

THE MAGNETIC MOMENT OF IRON IN CHROMIUM AND CHROMIUM ALLOYS

La susceptibilité magnétique de Cr 1-3 at% Fe, Cr 2 at% Si 2-3 at% Fe et Cr 0.5-1 at%V 3 at%Fe a été mesurée en fonction de la température de 4,3 à 340 K. On conclut que les atomes de fer isolés sont à l'origine de la susceptibilité indépendente de la température et que les atomes de fer voisins suivent à peu près la loi de Curie dans la phase commensurable.The magnetic susceptibility of Cr 1-3 at% Fe, Cr 2 at% Si 2-3 at% Fe and Cr 0.5-1 at%V 3 at% Fe has been measured in the temperature region 4.3-340 K. It is inferred that isolated Fe atoms give rise to a temperature independent susceptibility and nearest neighbour Fe atoms nearly follow the Curie law in the commensurate spin-density-wave state

RESISTANCE MINIMA IN AMORPHOUS MIXED MAGNETIC SYSTEM Fe-Mn-PBAl

Des études de la résistivité d'un système amorphe Fe-Mn-PBAl montrent un minimum de résistivité à des températures comprises entre 100 et 255 K. On trouve que ρ(T)-1 [dρ(T)/dT] dépend linéairement de ρ(T) aux températures inférieures à Tmin, ce qui donne pour la contribution dominante à ρ au-dessous de Tmin une dépendance exponentielle en T. Ceci est aussi observé dans plusieurs autres systèmes amorphes étudiés.Resistivity studies on amorphous Fe-Mn-PBAl system show ρmin at temperatures in the range 100-255 K. It is found that ρ(T)-1 [dρ(T)/dT] depends linearly on ρ(T) below Tmin, thus giving a simple exponential T-dependence for the dominant contribution to ρ below Tmin. This behaviour is also observed in several other amorphous systems studied by us