Decomposition of amorphous phase in Ni70Mo10B20 alloy above glass transition temperature

Phase transformation of amorphous Ni70Mo10B20 alloy (numbers indicate at.%) upon heating above the glass transition temperature Tg have been studied by X-ray diffraction, transmission and high resolution electron microscopy and differential scanning calorimetry. Decomposition of amorphous phase to the regions depleted and enriched in Mo and/or in B occurs at heating above Tg. Each type of these regions has been found to crystallize independently of others by primary crystallization mechanism. The crystallization above glass transition temperature leads to nanocrystalline structure formation. The crystallization mechanism and specific feature of the crystallization above Tg are discussed.