J. Phys. IV France 112 (2003) 731
Crystallization studies of amorphous melt-spun Ti Ni CuP. Schlossmacher1, N. Boucharat2, H. Rösner2, 2 and A.V. Shelyakov3
1 Forschungszentrum Karlsruhe GmbH, Institut für Materialforschung, P.O. Box 3640, 76021 Karlsruhe, Germany
2 Forschungszentrum Karlsruhe GmbH, Institut für Nanotechnologie, P.O. Box 3640, 76021 Karlsruhe, Germany
3 Moscow Engineering Physics Institute, Department of Solid State Physics, Kashirskoe Shosse 31, 115409 Moscow, Russia
Amorphous ribbons of the ternary shape memory alloy Ti 50Ni 25Cu 25 crystallize polymorphously upon heating. The subsequent growth proceeds isotropic resulting in the formation of perfectly spherical grains in an amorphous matrix at intermediate stages of the transformation. These experimental results match exactly with the idealized preconditions that are employed in various models describing nucleation- and growth kinetics at deep undercooling. Therefore, amorphous Ti 50Ni 25Cu 25 is an ideal candidate to study the crystallization by calorimetry in conjunction with microstructure analyses and to compare the results with theoretical predictions. It was found, that the isothermal crystallization process of Ti 50Ni 25Cu 25 near the glass transition can be adequately described by Johnson-Mehl-Avrami-Kolmogorov (JMAK) kinetics using an Avrami exponent of . Kissinger analysis of nonisothermal crystallization using different heating rates revealed an activation energy of kJ/mol.
© EDP Sciences 2003