The two-way shape memory effect (TWSME) has been studied in an amorphous–crystalline thin ribbon
of Ti40.7Hf9.5Ni44.8Cu5 shape memory alloy with different volume fractions of the crystalline phase. It is
found that an increase in the volume fraction of the crystalline phase results in a non-monotonic
variation in the value of the TWSME. A maximum strain of 1.1% is observed in the thin ribbon with a 50%
crystalline phase. It is found that the TWSME in amorphous–crystalline Ti40.7Hf9.5Ni44.8Cu5 alloy is due to two mechanisms: the formation of high internal stresses on the amorphous/crystalline interfaces due to
incompatible strain in amorphous and crystalline phases and the stress caused by defects induced in the
crystalline phase during deformation. If the volume fraction of the crystalline phase is 50% or less, then
the main contribution to the total TWSME is given by the formation of the internal stresses on the
amorphous/crystalline interfaces. In this case, the TWSME value depends on the density of the
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