Dw. Donovan et al., X-RAY STUDY OF THE MARTENSITIC-TRANSFORMATION IN AN INDIUM-THALLIUM ALLOY, Acta metallurgica et materialia, 42(6), 1994, pp. 1985-1996
Single crystal X-ray measurements of the temperature dependence of the
lattice parameters of In0.73 Tl0.27 between 25 and 300 K were perform
ed in order to search for a pretransformation tetragonal phase above t
he fc.c.-fc.t. martensitic transformation at 165 K, as previously foun
d for Fe-Pd by Seto et al. [H. Seto, Y. Noda and Y. Yamada, J. Phys. S
oc. Japan 57, 3668 (1988); 59, 965 (1990)] and in order determine, in
conjunction with ultrasonically measured room temperature elastic data
, the parameters of the Landau free energy for the O(h)-D4h proper fer
roelastic transformation, The mechanical stability limit of the cubic
phase and the third and fourth order elastic moduli depend on thermal
cycling through the transformation, but their ratio and the transforma
tion temperature T0 remained constant. In the as-grown state of the cr
ystal all model parameters are consistent with those measured ultrason
ically by Brassington and Saunders [Proc. R. Soc. A387, 289 (1983)]. T
he directly measured volume change at T0 was found to be negative, con
sistent with the positive pressure coefficient of T0 for In0.77Tl0.23
[G. A. Saunders, J. D. Comins, J. E. Macdonald and E. A. Saunders, Phy
s. Rev. B34, 2064 (1986)]. No pretransformation tetragonal phase about
T0 was found.