A TIME-RESOLVED X-RAY-DIFFRACTION STUDY OF TI5SI3 PRODUCT FORMATION DURING COMBUSTION SYNTHESIS

Time-resolved x-ray diffraction (TRXRD) was performed during Ti5Si3 sy nthesis by the self-propagating high-temperature synthesis mode for di fferent Ti size fractions. It was determined that the time for product formation (ca. 15 s) was independent of Ti particle size. However, th e formation of Ti5Si4 phase occurred when relatively large titanium pa rticles were used. A simultaneous measurement of the temperature and T RXRD allowed us to attribute the shifting of XRD peaks at high tempera ture to thermal expansion of tile Ti5Si3 product, The thermal expansio n coefficients differ for different crystal planes, and their numerica l values compare well with those report-ed previously in the literatur e.