Process And Properties Of Ti-Si-C Ceramic Reinforced Titanium Matrix Composites Prepared Based On Electron Beam Treatment

Titanium alloys have excellent properties such as high specific strength,corrosion resistance and high temperature resistance,and received extensive attention in the aerospace industry.Titanium matrix composites make titanium alloy higher strength and wear resistance,and are expected to meet more demanding service environments.However,the traditional casting method and the powder metallurgy method can form large reinforcement grains,then easily cause wear and scratch on the surface of the material during the friction process.For this reason,the plasma pre-sintering and high energy electron beam processing technology are used in this paper.A Ti-Si-C ceramic reinforced titanium matrix composite with a network structure and fine reinforcements was in situ synthesized to improve the friction and wear properties of Ti6Al4 V titanium alloy.Ti6Al4V titanium alloy powder was used as the matrix and SiC powder as the pre-additive.After the plasma pre-sintering,the titanium matrix composites were prepared by electron beam processing technology.The titanium matrix composites were analyzed by X-ray Diffraction,X-ray Photoelectron Spectroscopy,Optical Microscopy and Scanning Electron Microscopy,Microhardness and friction test were carried out to investigate the phase composition,microstructure,microhardness and wear resistance of titanium matrix composites to explore the effect of the electron beam current,the electron beam moving speed and particle size of SiC powder on the regularity and mechanism of the composite microstructure and properties.The results showed that the reactions between Ti and SiC in the electron beam treatment generated in-situ synthesized plate/dendritic TiC,ultra-fine needle-like Ti5Si3 and lath-like Ti3SiC2 three ceramic reinforcements,and the lath-like Ti3SiC2 connected with each other,forming a peculiar network structure.The network structure was more obvious when the beam current was higher or the electron beam moving speed was smaller.The larger the SiC particle size was,the better the network structure was formed.When the beam current was too large or the electron beam moving speed was too small,coarse crystal grains were likely to be formed,and when the SiC particle size was small,rod-like structures which were uniformly distributed were formed.Through the microhardness and friction tests,it was found that as the beam current increased or the electron beam moving speed decreased,the microhardness first increased and then decreased,the wear rate decreased first and then rised.When the composite material prepared with large sized SiC particles,the microhardness was high and the wear resistance was superior.Therefore,the SiC particle size with the best wear resistance was 50μm.The optimal process parameter was the beam current of 10 mA and electron beam moving speed of 10mm/s.The prepared titanium matrix composite formed a complete network structure and plate/ dendritic structure and ultrafine needle like reinforcements.The microhardness increased by 58% and the wear rate decreased by 54% compared with the titanium alloy without SiC additive.