  Using a variety of thermodynamic measurements made in magnetic fields, we
show evidence that the diffusionless transition (DT) in many shape-memory
alloys is related to significant changes in the electronic structure. We
investigate three alloys that show the shape-memory effect (In-24 at.% Tl,
AuZn, and U-26 at.% Nb). We observe that the DT is significantly altered in
these alloys by the application of a magnetic field. Specifically, the DT in
InTl-24 at.% shows a decrease in the DT temperature with increasing magnetic
field. Further investigations of AuZn were performed using an ultrasonic
pulse-echo technique in magnetic fields up to 45 T. Quantum oscillations in the
speed of the longitudinal sound waves propagating in the [110] direction
indicated a strong acoustic de Haas-van Alphen-type effect and give information
about part of the Fermi surface.
