The thermoelastic martensitic transformation and the stress-strain behaviour
associated with the transformation in manganese-rich Mn-Cu alloys have been
examined by tensile testing using single crystals grown by the Bridgman method.
In the case of the deformation below the martensitic transformation temperature,
twinning deformation in f.c.t. martensite has preceded dislocation glide, and the
strain due to twinning showed a shape-memory effect. Regarding the continuous
lattice parameter change, which can be observed in the temperature region
extending over 100 K below the transformation temperature, the twinning strain
decreased gradually by increasing the deformation temperature. It is shown that
the shape-memory strain can be estimated by assuming the configuration of the
twin-related domains of the f.c.t. martensite. Just above the transformation
temperature, a stress-induced transformation has been found in the tensile testing.
The characteristics of the stress-induced transformation from cubic to tetragonal
structure in this alloy is discussed.