The Formation Of Al-Ti-C Composites Via Combustion Synthesis

Al-Ti-C grain refiner was produced by combustion synthesis. In this reaction, aluminum, titania and graphite were used as reactants. The adiabatic temperature of Al-Ti-C in the combustion synthesis reaction was calculated and theoretically analyzed on the base of thermodynamics theory. Reaction mechanism was studied by the Combustion Front Quenching (CFQ) experiment , the influence of changing the reactants' component and combustion mode on the reaction results.The ability of grain refine of Al-Ti-C composites for pure aluminum was tested.Thermodynamics analysis indicated that the reaction was promoted by increasing the warm-up temperature and the warm-up temperature should not low at 623K.The influence of changing the reactants; component and combustion mode on the reaction process was investigated by analyzing temperature change during the reaction process and X-ray Diffractometer(XRD) and Scanning Electron Microscope(SEM) for the reaction products. The results shows,content of titania and graphite and the ratio of Ti:C and the combustion mode all have obvious influence on the grain size, configuration and distribution of the phase in the finally products of reaction.According to the CFQ experiment, the finally produts were Al3Ti and TiC . No any other phase exist, and the reaction equation was deduced. The different area of CFQ samples was observated and analyzed through XRD and SEM. Under the SHS( self-propagating high-temperature synthesis) mode, firstly, solide Al3Ti was formed by reaction of solide Al and Ti, the temperature increseed and aluminum melt to met the graphite. Then the graphite diffused and reacted with Al3Ti . So TiC was produced. During the cause of cooling ,the solid TiC was separated out. In the mode of TE, the Al3Ti was melt after produced . TiC was separated out from Al next to being separated out from Al3Ti. Nearly no diffusion of the graphite was needed.Via performance testing of every sample, the optimal prescription was worked out. The role of each composity in the alloy was also determined. On the meanwhile,comparatiom of permance of the best sample with the imported Al-5Ti-B wire was compeleted.