Dispersion technique studies on Pd43Ni10Cu27P20

Crystallization of undercooled Pd43Ni10Cu27P20 melts is studied by dispersing the sample into about 300 particles that are processed simultaneously. The size is chosen in such a way that crystallization of each individual particle can be detected. In isothermal experiments at high temperatures, above the nose of the time–temperature–transformation (TTT) diagram, the onset of crystallization of individual particles is spread out over up to 104 s. In contrast, all particles crystallize simultaneously below the nose and the crystallization is not distinguishable from that of one large sample. The results suggest that the dominant crystallization mechanism changes in a very narrow temperature range from a nucleation-controlled process at high temperatures to a growth-controlled process at low temperatures. The dispersed sample setup together with the nature of the nucleation and crystal growth process enable to directly measure the nucleation and growth rates in the nucleation controlled temperature region as a function of temperature.