Annealing effects on the crystallization and shape memory effect of Ti50Ni25Cu25 melt-spun ribbons

Crystallization of amorphous NiTiCu thin films

“…1 shows our DSC curves of NiTi and NiTiCu thin films under different heating rates with the peak crystallization temperature, T p , indicated. Previous research has shown a decrease in crystallization temperatures and activation energies with a significant amount of copper addition (≥10 at%) [7][8][9][10][11][12][13][14]. The peak crystallization temperatures appear to remain nearly the same after adding a small amount of copper (of 1.3 at.%).…”

“…Preliminary studies on the crystallization behavior of NiTiCu have been done using differential scanning calorimetry (DSC) and X-ray diffraction [7][8][9][10][11][12][13][14]. However, most studies describe only the overall crystallization process rather than determining the individual contributions of nucleation and growth.…”

Shape memory characteristics of as-spun and annealed Ti51Ni49 crystalline ribbons

“…Recently, melt-spinning technique has been utilized to fabricate amorphous or crystalline Ti-Ni binary and Ti-Ni-Cu ternary SMA ribbons for various applications. Among them, Ti 50 Ni 25 Cu 25 ribbon was widely studied because of its unique properties, such as small transformation hysteresis, low flow stress level in the martensite state, low sensitivity of the martensitic transformation start (Ms) temperature and easy fabrication for fully amorphous melt-spun ribbons [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. These advantages make Ti 50 Ni 25 Cu 25 ribbon a good candidate for applications, such as actuator and sensor that require short response time at thermal cycle.…”

“…Nevertheless, it is very difficult to control the appropriate annealing conditions for Ti 50 Ni 25 Cu 25 ribbon [17,18]. This is because no obvious martensitic transformation can be observed before Ti 50 Ni 25 Cu 25 ribbon is sufficiently crystallized.…”

Annealing behaviour of nanocrystalline NiTi (50 at% Ni) alloy produced by high-pressure torsion

“…One prominent example is the size effect that can significantly shift the transformation from the cubic B2 high temperature phase to the monoclinic B19' martensite; grains with a size less than 50 nm can even lead to the complete suppression of the transformation [15,16]. [17][18][19][20], melt spinning (MS) [21][22][23][24] and cold rolling [25,26].…”