Study On The Reaction Mechanism And Properties Of Ti-Al-B And Ti-Al-C Composites Fabricated In-situ By Microwave Thermal Explosion Method

In this paper,the titanium aluminum matrix composite reinforced by TiB2/TiC particles is fabricated by microwave thermal explosion in situ synthesis method from Ti-Al-B/Ti-Al-C system.The DSC curve and the microwave thermal explosion reaction heating curves are used to analyze the thermodynamic and kinetic process of Ti-Al-B and Ti-Al-C reaction.The reacted products are identified by XRD(X-ray diffraction),SEM(scanning electron microscope),EDS(energy dispersive spectrometer).What’s more,the oxidation properties and compression properties of the fabricated products are tested in this article.The results show that:all of these two system can react following the direction of thermodynamic.There are two main reaction steps in both Ti-Al-B/C system.The activation energy of Ti-Al-B system is 723.8kJ/mol and 310.1kJ/mol respectively.And the activation energy of Ti-Al-C system is 435.6kJ/mol and 466.3kJ/mol respectively.But there is only one reaction peak in microwave synthesis period both in two reaction system.The activation energy of Ti-Al-B and Ti-Al-C system is 43.2kJ/mol and 27.0kJ/mol respectively.Micro structure analyses show that:in thermal explosion reaction products,the reinforcement is TiB2 and TiC particle respectively and the matrix is consisted by TiAl and Ti3Al.Meanwhile,there are some reaction zone left in the Ti-AI-B system products.The reinforcement in 5vol.%Ti-Al-B/C is less,while that is more in 10vol.%Ti-Al-B/C.But there are more micro pits in 10vol.%Ti-Al-B/C.What’s more,the products made by 2h-milling-time are better than 6h-milling-time.And higher sintering temperature and longer warm-keeping time can do better to the mesophase to decompose.The property studies shows that:the property of TiAl matrix composite(5vol.%)is better than that made by traditional preparation method and TiAl matrix made by microwave method.The density of the products can promote to 82-85%,the highest HBW is 44.92N/mm2.The Kp in 900 ℃reduces to 0.010628-0.014618 mg2/(mm4·h).The compression strength of 5vol.%Ti-AI-B/C can promotes to 450MPa and 760MPa,compression ratio reaches to 9.98%.The improvement of compression property mainly roots from dislocation strengthening mechanism and load-wearing strengthening mechanism.