Phase transition induced anelasticity in Fe–Ga alloys with 25 and 27%Ga

Neutron diffraction and mechanical spectroscopy techniques were applied to study phase transitions in Fe–Ga alloys with 25 and 27 at.% Ga. The following sequences of phase transitions at continuous heating and subsequent cooling in the 20–900 °C temperature range were recorded: D0₃ → L1₂ (limited amount) → A2(B2) was recorded at heating and A2(B2) → D0₃ at cooling for Fe-24.8Ga alloy, and the D0₃ → L1₂ → D0₁₉ → A2(B2) was recorded at heating and A2(B2) → L1₂ at cooling for Fe-27.4Ga alloy. Thus, the difference in 2.6 at.%Ga between two studied compositions with D0₃ structure leads to their different structures after heating to 900 °C. These transition sequences determine different temperature dependencies of elastic and anelastic properties. The D0₃ → A2(B2) transition (in Fe-25Ga) does not lead to a well-pronounced anelastic effect, in contrast the D0₃ → L1₂ transition (in Fe-27Ga) generates internal stresses due to a different rate of an increase in the lattice parameter with temperature and leads to a well-pronounced transient internal friction effect. - Highlights: • Neutron diffraction technique is used to study in situ phase transitions in Fe-25 and 27 at.% Ga. • D0₃ → L1₂ → D0₁₉ → A2/B2 transitions were recorded at instant heating in Fe-27 at.% Ga. • D0₃ → L1₂ (limited amount) → A2(B2) was recorded at instant heating in Fe-25 at.% Ga • The D0₃ → L1₂ transition generates internal stresses and leads to elastic and anelastic response