Model experiment on reactive phase formation and solidification of B4C-BN composites via nanosecond pulse laser processing.

In the present work we describe results of a model experiment on reactive phase formation of B4C-BN composites on a steel substrate using high-energy short laser pulses. The model experiment opens a way for high quality laser joining of boron based ceramics with steels through the reactive phase formation at the steel-ceramic interface. The study was focused on changes in microstructure, chemical and phase compositions in surface layers of the resulting B4C-BN-Fe composites. Ultrafine powders of boron carbide and boron nitride were spread on a steel surface and subjected to laser processing with nanosecond pulses. The reactions occur as a result of elevated temperature under action of laser short pulses. Subsequent rapid solidification leads to highly nonequilibrium solidification and metastable phase formation. [ABSTRACT FROM AUTHOR]