Staff Members - Benha University
First- and second-order phase transitions in Fe-(17-19)at.%Ga alloys
Materials Letters • 2020
Publication Information
Authors
A.K. Mohamed, V.V. Cheverikin, S.V. Medvedeva, I.A. Bobrikov, A.M. Balagurov, I.S. Golovin
Keywords
Fe-Ga, Phase transformations, Cooling rates, Grain boundaries, TTT diagram, Diffusion
Journal
Materials Letters
Publisher
Elsevier BV
Volume
279
Issue
Not Available
Pages
128508
publication.type
International
Paper Link
Open Link
Supplementary Materials
Not Available
Abstract
The structure of the Fe-(17.5–19.5)at.%Ga alloys in as-cast and nearly equilibrium states is studied using
XRD, ND, and EBSD. In disagreement with the existing phase diagrams, the long-term isothermally
annealed at 450–500 C Fe-17.5%Ga alloy has a two-phase structure with two co-existing ferromagnetic
phases: bcc-originated A2(D03) as a matrix and a fcc-originated A1(L12) needle-shaped precipitates. The
phase transitions during cooling of 17.5 and 19.5%Ga alloys from the A2 range of the phase diagram with
different cooling rates were used to plot, at least partly, Time-Temperature-Transformation (TTT) diagrams.
The critical cooling rates for starting first- and second-order transitions are determined for the
Fe-19.5%Ga alloy. The effect of long-term annealing on magnetostriction is reported.
XRD, ND, and EBSD. In disagreement with the existing phase diagrams, the long-term isothermally
annealed at 450–500 C Fe-17.5%Ga alloy has a two-phase structure with two co-existing ferromagnetic
phases: bcc-originated A2(D03) as a matrix and a fcc-originated A1(L12) needle-shaped precipitates. The
phase transitions during cooling of 17.5 and 19.5%Ga alloys from the A2 range of the phase diagram with
different cooling rates were used to plot, at least partly, Time-Temperature-Transformation (TTT) diagrams.
The critical cooling rates for starting first- and second-order transitions are determined for the
Fe-19.5%Ga alloy. The effect of long-term annealing on magnetostriction is reported.