Influence of sintering temperature on microstructure and mechanical properties of(Ti5Si3+TiC+TiB)/Ti composites
In order to obtain titanium matrix composites with excellent performance and to solve the problems such as limited relative performance enhancement of single reinforcement,in situ synthesized TiB,TiC and Ti5Si3 reinforced Ti composites at different sintering temperatures were produced by powder metallurgy of Ti powder,SiC powder,TiB2 powder and C powder.The microstructure and mechanical properties of the composites were analyzed by XRD,SEM and universal testing machine.The results showed that with the increase of sintering temperature,the density of the composites increased and the average grain size increased gradually.With the increase of sintering temperature,the number of reinforcement increased and the frequency of agglomeration phenomenon which occurs at lower sintering temperature decreased.The Rockwell hardness,yield strength and tensile strength of the composites firstly increased and then decreased as the sintering temperature increased,while there was no obvious decrease in the fracture strain.At 1 300 ℃,(Ti5Si3+TiC+TiB)/Ti composite had the best comprehensive mechanical properties.Moreover,the sintered sample had the highest compressive strength of 2 435 MPa,yield strength of 1 649 MPa,Rockwell hardness of 49.1 HRC and fracture strain of 28.7％.Based on the analysis,the synergistic effect of micron-sized TiC,TiB and sub-micron-sized Ti5 Si3 reinforcement can significantly improve the strength and maintain plasticity at the same time.The main strengthening methods of(Ti5 Si3+TiC+TiB)/Ti composites are fine crystal strengthening,dispersion strengthening and load transfer strengthening.
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