| Laminated metal composite materials have attracted attention at home and abroad for their good mechanical properties.The layered Ti-based composite material combined the ductility of the metal matrix and the high strength of the reinforcing material significantly improve the room temperature and high temperature mechanical properties.It can not only retain the excellent characteristics of traditional titanium alloys,but also improve the various properties of the titanium matrix.Such as strength,wear resistance and corrosion resistance,etc.Most of the reinforcements in the previous researches are evenly distributed in the titanium matrix,and the strength enhancement of the composite material is low(?15%).In order to further improve the strength of the composite material,it is necessary to distribute the reinforcements heterogeneously,thereby increasing the volume fraction of the reinforcements,which has important scientific significance and application value for layered titanium-based composites.In this paper,layered pure Ti is used as the substrate,and GO and Si are deposited on the surface by electrophoretic deposition(EPD).A layered structure of Ti-based composite material is prepared by spark plasma sintering(SPS),using metallographic microscope and scanning electron microscope and XRD analyzed the microstructure of layered Ti-based composites,and tested its mechanical properties.The effects of deposition time,Si/GO ratio and Ti foil thickness on the microstructure and mechanical properties of layered Ti-based composites were studied.The strengthening and toughening mechanism of layered metal composites were discussed,which played a guiding role for its preparation.(1)During the SPS process,the GO and Si deposited on the surface of the Ti foil react with Ti respectively,and then generate TiC and Ti5Si3 reinforcements in-situ between the Ti foil layers.The content of the reinforcements has a linear relationship with the electrophoretic deposition time.As the deposition time increases,the volume fraction of the reinforcement increases;the volume fraction of Ti5Si3 and TiC reinforcement phases increase with the increases of the ratio of Si/GO in the deposition solution;the thickness of Ti foil increases,and the volume fraction of Ti5Si3 and TiC reinforcement phases decreases.When the reinforcement is continuous,the grain size of the Ti matrix decreases,and the layered structure of the Ti-based composite material becomes more and more obvious.(2)As the volume fraction of the reinforcement increases,the strength of the Ti-based composite material increases.When the GO is deposited alone,the maximum yield strength of the composite material can reach 696 MPa,which is?133.5%higher than that of pure titanium(298 MPa),and the composite material maintains an elongation of 6.1%.When Si/GO=2:1,the maximum yield strength of the composite material can reach 969 MPa,which is?225.2%higher than that of pure titanium,39.2%higher than that of the GO deposited alone,and the elongation of the composite material is 5.1%.When the thickness of the Ti foil layer is 0.2 mm,the lowest yield strength of the composite material is 491 MPa,which is?53.9%higher than that of pure titanium(319 MPa),and the composite material maintains an elongation of 25.2%.(3)The strengthening of the layered(Ti5Si3+TiC)/Ti composite material is attributed to the solid solution strengthening,grain boundary strengthening,including the strength provided by the reinforcement itself and the strengthening of the load transferred from the matrix,and the strengthening caused by component mismatch,including heat Residual stress and synergistic strengthening.The fracture mechanism is:cracks are first formed in(Ti5Si3+TiC),and as the load increases,these cracks extend into the Ti matrix along the network boundary of the(Ti5Si3+TiC)composite layer.With the cracking of the(Ti5Si3+TiC)/Ti composite layer and the local plastic necking and the local shear bands in the Ti layer,the layered(Ti5Si3+TiC)/Ti composite material fails. |
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