Phase States and Structural Phase Transitions in Fe73Ga27RE0.5 (RE = Dy, Er, Tb, Yb) Alloys: A Neutron Diffraction Study

New data on phase states and structural phase transitions in alloys Fe₇₃Ga₂₇ doped with Dy, Er, Tb, and Yb in an amount of about 0.5 at % are presented. Structural data were obtained in neutron diffraction experiments performed with high resolution and in continuous temperature scanning mode during heating to 850°C and subsequent cooling at a rate of ±2°C/min. It has been established that both the sequence of forming and disappearing structural phases and the final state of the alloy depend on the type of rare earth element. Phase transitions in the alloy with Dy are similar to those in the initial Fe₇₃Ga₂₇ alloy, excluding the final state. The procedure of doping with Er and Tb leads to the formation of disordered A1 and A3 phases instead of the L1₂ and D0₁₉ ordered close packed phases, respectively. In the case of doping with Yb, neither of the above phases is observed. The formation of the L6₀ (m-D0₃) and D0₂₂ tetragonal structural phases previously discovered in similar alloys by the electron diffraction method is not confirmed.