X-ray spectrum study of borosilicide coating on niobium alloy

Using the methods of ultramild X-ray spectroscopy and diffractometry element and phase profile of borosilicide coating on niobium alloy at the stage of its formation and after high-temperature annealing in the air in the temperature range 1100-1400 deg C for 1.5-10 h have been investigated. It is established, that after annealing upon the coating surface SiO2 oxide film is formed, alloyed by oxides of coating and sublayer elements. Then, threre is a thin transition layer of Nb5Si3, transforming into disilicide, under which up to initial alloy the layer of niobium diboride is located. It is noted, that with the temperature and annealing duration increase the growth of oxide layer thickness and interaction between disilicide and boride phases inside the coating, as well as coating-alloy boundary blurring, are observed