Burst Character of Thermoelastic Deformation of Shape Memory Alloys in Single Crystal Ni-Fe-Ga-Co and Cu-Al-Ni

Thermoelastic deformations during martensetic transformation in SMA based on NiFeGa and CuAlNi have been studied. It was shown that in the Ni-Fe-Ga-Co alloy such effect is highly anisotropic. In case of compression along [100] axis (6%) shape recovery is starts at 297 K and takes 4 K interval. In another case, when compression is conduct along axis [110], shape recovery starts at 361 K and takes about  10^-3 K interval, i.e. has a burst behavior. As a result, free standing on firm ground crystal weighing 1.2 g and a volume of 4x4x9mm³under the influence of floor reaction acquires a velocity of 22 m/s and reaches a height of 23 m. While the velocity of specimen that was deformed along [100] direction is less than 1.8 mμ/s. Similar result has been obtained by compressing (8%) of crystals of the alloy CuAlNi in the crystallographic direction [100], where a burst recovery occurred at 390 K, it is by 66 K higher than the martensitic transformation temperature in initial samples. The authors believe that such effect can be observed in any SMA, which may form the γ’ martensite, in one of crystallographic directions.  It is assumed that the observed phenomenon can be used to create fast shape memory drivers and other devices.