A Study of Interfacial Reactions in Titanium/Sapphire (Al2O3) Composites

摘要

The reactions between sapphire filaments and Ti70A and Ti75A matrices were studied over the temperature range 600 to 1000C for various times. The filament decomposed through diffusion of both aluminum and oxygen into the Ti matrix, resulting in a series of Ti(x)Al(y) compounds formed adjacent to the filament with aluminum and oxygen diffusion gradients ahead of the zone. Two rate constants were measured for the reaction zone growth; an activation energy of 23 Kcal/mole was calculated above 800C and a value of 53 Kcal/mole below. It was determined from Microhardness measurements in the matrix that oxygen diffusion was primarily occurring. Unless the embrittling effects of the reaction can be controlled, it appears that Ti/al2O3 composites will not be a viable system as compared to Ti/B or ti/SiC composites. (Author)