The long-range order parameter of the fcc ordered ${\mathrm{Fe}}_3$Al structure, as measured by x-ray scattering, varies as ${(T_c-T)}^{\beta }$, with $\beta =0.307\mathrm{}$, in the range between 1 and about 10 K below $T_c$ (823 K).

• Received 20 November 1968

DOI:https://doi.org/10.1103/PhysRevLett.22.517