Mechanical spectroscopy of atomic ordering in Fe-(16-21)Ga-RE alloys

Anelasticity of Fe-(16-21)at% Ga-RE (rare earth RE = La, Tb, Dy, Er, Yb elements) alloys at room and elevated temperatures is studied in a sub-resonance mechanical spectroscopy. Two thermally-activated and two transient effects are recorded in most of the studied alloys. To explain these phenomena, structure and phase transitions in several binary and ternary Fe-Ga alloys are investigated. The D0(3) ordering of rapidly cooled alloys with the A2 structure at heating at around 300 degrees C and the disordering at heating and the D0(3) ordering at cooling around 500 degrees C for annealed samples are proved using three in situ techniques: neutron diffraction, vibrating sample magnetometry, and internal friction and supported by positron annihilation experiments. Thermally activated transitory effects are tentatively explained by stress-induced reorientation of Ga-Ga, vacancy-vacancy pairs, and carbon atoms jumps. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

The anelasticity of Fe-(16-21)at% Ga-RE alloys was studied at room and elevated temperatures, revealing two thermally-activated and two transient effects in most alloys. Investigation into the structure and phase transitions of Fe-Ga alloys helped explain these phenomena. In situ techniques such as neutron diffraction, vibrating sample magnetometry, and internal friction provided evidence for D0(3) ordering and disordering processes in the alloys, supporting the tentative explanation of thermally activated transitory effects.