Crystallization and Anomalous Thermal Expansion of Amorphous Ni-P Alloy

The relation between the crystallization and the specific linear expansion of an amorphous Ni-P alloy caused by heating was investigated. When the amorphous Ni-P was heated from 27°C to 450°C, Ni5P4 crystals containing Ni, NiP crystals containing Ni, and Ni3P and NiP2 crystals containing Ni grew at 270°C, 370°C and 410°C, respectively. Alternatively, when the amorphous Ni-P was heated under the same conditions as above, anomalous specific linear expansion was observed at the above-mentioned three temperatures. By the use of the results of the existence ratio of crystals and X-ray measurement of their thermal expansion, it was possible to calculate the anomalous specific linear expansion as a function of temperature.