Research On The Self-assembly Synthesis Technology Of Ti-Al Layered Composites

Ti-Al layered composites have high strength and high plasticity of TiAl intermetallics.They have high density and high specific strength.In recent years,TiAl layered composites have been used in the field of aerospace and can be used as an armed helicopter Excellent equipment for armor.However,the Ti-Al layered composites prepared by conventional methods such as pure Ti and pure Al as the substrate have low toughness and toughness,and Ti and Al are required to form intermetallic compound by long-term high temperature annealing.The preparation efficiency is low,which seriously limits the wide application of this kind of composite material.In this study,the activation properties of amorphous materials were introduced.The Al-Ti-based amorphous-Al and Ti-Al-based amorphous-Ti modules were used as the object of study to explore the possibility of directly fabricating layered composites by hot pressing.The microstructure and the growth kinetics of the layered composites are of great significance to the engineering application of Ti-Al layered composites.In this paper,Ti-based amorphous foil and Al-based amorphous foil were prepared by vacuum quenching method.The Al-TiAl intermetallic compound-Al and Ti-TiAl intermetallics were prepared by hot pressing method using Gleeble thermal simulation tester.Compound-Ti laminated composite.The TiAl intermetallic compound layer is obtained by reacting a Ti-based amorphous-Al foil and an Al-based amorphous-Ti foil,respectively.At the same time,the microstructures of the prepared composite composites were analyzed by SEM,and the influence of hot pressing temperature and holding time on the microstructure of the layered composites was determined.The reaction product type was determined.Finally,the diffusion reaction layer of the growth dynamics model.The main conclusions are as follows:(1)The reaction products of Ti-based amorphous and Ti-Al and Al-Ti composites were TiAl3,which was consistent with the thermodynamic analysis results in the temperature and holding time range.(2)560?,the amorphous foil and metal Ti or Al layer did not react;when the temperature rose to 600?,the amorphous foil and metal Ti or Al began to react,and with the temperature and holding time,The thickness of the reaction layer is increased.Ti-AlTi-Al layered composites were formed after the Ti-based amorphous alloy was mixed with Al for 4h at 640?.Al-Ti-TiAl-Ti layered composites were formed when the Al-based amorphous was combined with Ti for 6h at 620?.(3)The kinetic model of the growth of the reaction layer in Al-TiAl-Al and TiTiAl-Ti layered composites was fitted.From this model,it was found that the activation energy Q?7.32×106J?mol-1and the new phase growth rate K0?1.80×109,Ti-TiAl-Ti in the reaction layer growth activation energy Q?1.42×105J?mol-1,the new phase growth rate K0?3.34×109.(4)Ti-Al layered composites were prepared by the reaction of pure Ti and pure Al directly.When Ti-based amorphous and pure Al and Al-based amorphous and pure Ti were reacted,the latter TiAl intermetallic reaction The growth rate of the layer is higher than that of the former,and the activation energy of the reaction layer is lower than that of the former,which indicates that the heat released from the crystallization of the amorphous material during the hot pressing process does promote the growth of the TiAl intermetallic compound reaction layer And the preparation efficiency of the layered composite material is improved to a certain extent.(5)The yield strength of Al-TiAl-Al layered composites at room temperature is 220 MPa,the tensile strength is 850 MPa,the fracture strain is 35.9%,and the comprehensive mechanical properties are better.The tensile stress-strain curve appears serrated,indicating that the layers in the composites are not broken at the same time.The fracture order of each layer should be: TiAl intermetallic compound layer,Al layer and Ti-based amorphous layer after crystallization.A large number of dimples appear in the fracture of the material,indicating that it is broken in a ductile mode,that is,it has better plastic toughness than TiAl intermetallics.