Magnetic phase separation in ordered alloys

We present a lattice model to study the equilibrium phase diagram of ordered alloys with one magnetic component that exhibits a low temperature phase separation between paramagnetic and ferromagnetic phases. The model is constructed from the experimental facts observed in Cu$_{3-x}$AlMn$_{x}$ and it includes coupling between configurational and magnetic degrees of freedom which are appropriated for reproducing the low temperature miscibility gap. The essential ingredient for the occurrence of such a coexistence region is the development of ferromagnetic order induced by the long-range atomic order of the magnetic component. A comparative study of both mean-field and Monte Carlo solutions is presented. Moreover, the model may enable the study of the structure of the ferromagnetic domains embedded in the non-magnetic matrix. This is relevant in relation to phenomena such as magnetoresistance and paramagnetism.Comment: 12 pages, 11 figures, accepted in Phys. Rev.

ε AND α' MARTENSITE FORMATION AND REVERSION IN AUSTENITIC STAINLESS STEELS

The structures of α' and ε martensite in 18/8 and 18/12 steels, observed using electron microscopy techniques are reported. Structural changes associated with the reverse transformations of these phases to austenite, γ, on heating, together with compositional variations are presented and mechanisms of both the direct and reverse transformations are discussed

STRAIN INDUCED TRANSFORMATIONS AND PLASTICITY IN TRANSAGE Ti-11.6V-2Al-2Sn-6Zr (Tl134) AND Ti-11.5V - 2Al-2Sn-11.3Zr (Tl29) ALLOYS

An investigation is reported on two β quenched titanium Transage alloys, namely (i) T 134 which contains only orthorhombic α" martensite and (ii) T 129 which contains mainly retained β and a small amount of α" after quenching from the β phase. Strain induced shear, transformations of β to α" and the α" to hexagonal α' take place in the temperature range 77-373K and are associated with enhanced ductility

Laser surface nitriding of titanium and a titanium alloy

Surfaces of titanium and titanium alloy IMI829 have been nitrided by laser melting in nitrogen and in a gas mixture containing various proportions of argon and nitrogen. The nitrided layers have been characterised with respect to their hardness, microstructure, chemical composition, corrosion properties and surface finish. Observations are also reported on the laser remelting in argon of the as-formed nitrided layers and laser melting of nitride layers preformed by physical vapour deposition and furnace heating.Peer Reviewe