Thermodynamic Study Of TiC_p/Al Composite By Argon Arc Melting

Since the21st century, the development of particle reinforced aluminum composites technology is very active. TiC particles with a high melting point and thermal stability, high hardness, high elastic modulus, high bending strength, and good compatibility with the Al matrix, is reinforced materials’ideal for the aluminum alloy, and TiCp/Al composite has important applications in aerospace, precision instrument, automobile engine, sports equipment, electronic packaging etc.fields.But the research on the basic theory of TiCp/Al composites is still relatively weak, such as enhancing the prediction and control of the size of particles.The finer particles, the better the effects of reinforcement. Therefore, using appropriate techniques to reduce the formation of harmful intermediate products such as brittle Al3Ti, and to enhance the refinement of grain size, is always the goal of researchers in composite field.In this experiment, Al,C,Ti powders are evenly mixed according to a certain proportion, and pressed into blocks, then melting Al-Ti-C precast blocks with argon arc welding heat, and in-situ producing TiCp/Al composite. Select water-cooled copper mold and graphite crucible as the reaction vessel, and set different welding current and duration of preparation. Analysis the thermodynamic process of argon arc in-situ reaction,and calculate the solubility product of titanium and carbon under different temperatures in molten aluminum, and then discuss the free energy of all the reactions and its relationship with temperature. At the same time, by the DSC, XRD analysising and OM, SEM characterization methods, confirm the components of reaction products, test their properties, and verify the thermodynamic extrapolations.Results show that, products of in-situ reaction of Al-Ti-C alloy system may be generated by the TiC, Al3Ti and Al4C3, and the reaction free energy of synthesis TiC of solid carbon and solid titanium is minimum. Meanwhile TiC is the most stable in thermodynamics, so the trend of the maximum TiC synthesis reaction. It confirmed that the contents of components of each element in TiCp/Al composite are basically in accord with the preparation of Al-Ti-C mixed powder. At the beginning of Argon arc melting, the exothermic reaction made the temperature of system rise rapidly and accelerated the diffusion of C and Ti, so Ti and C synthesis of TiC.What’s more, it increased the reaction intermediate of TiAl3and Al4C3being transformed into TiC. When increasing the current to a certain degree, it will no longer obvious benefits for reaction process of composite.Thermodynamic study helps to reduce the formation of brittle AlTi, increase the content of TiC to achieve better effect, and make the composite appear to have better quality by controlling the temperature and the ratio of raw materials. The study provided the theoretical guidance and technical support for production in the preparation of TiCp/Al composite with high efficiency and no pollution.