Microstructure and properties of Ti/(TiB+TiC)composites prepared by low-cost TiH2 powders
Ti/(TiB+TiC)titanium matrix composites with the excellent mechanical properties were prepared by vacuum pressureless sintering and hot extrusion by using low-cost TiH2 powders instead of pure titanium powders and adding B4C to in-situ produce TiB and TiC reinforcements.The effects of preparation technology and reinforcements on the microstructure and properties of the Ti/(TiB+TiC)composites were analyzed.The results show that the TiH2 powders have the good sintering activity,and the relative density of the sample after dehydrogenation and sintering can reach 97.7%,which is further increased to 99.9%after the hot extrusion as closed to full density.The TiB reinforcements are short fibrous,and the TiC reinforcements are granular,which are uniformly distributed in the equiaxed α-Ti matrix,restraining the growth of equiaxed grains and refining the grains.The hot extrusion process can further refine the grains and make the microstructure more uniform and compact,the as-extruded titanium matrix composites show the high hardness and good matching of strength and ductility.The TiH2+4%B4C(volume fraction)extruded composites have the Vickers hardness of Hv0.3 310,yield strength of 683 MPa,tensile strength of 851 MPa,and elongation of 15.1%after fracture.
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