Research On Microstructure And Properties Of Ti6Al4V-xB₄C Matrix Composites Using Selective Laser Melting

This subject aims to improve the hardness,strength and toughness of Ti6Al4V.The Ti6Al4V-xB₄C composite material(x=0.01wt%,0.1wt%,1wt%,10wt%)was successfully prepared using selective laser melting technology.By analyzing the microstructure and strengthening and toughening mechanism of Ti6Al4V-xB₄C composites,The Ti6Al4V-xB₄C composite material with improved hardness,strength and toughness was obtained.By comparing the relative density of Ti6Al4V-xB₄C composites prepared under different laser energy densities,it was found that too high or too low energy density will lead to the decrease of relative density;At the same time,when the B₄C content is low,the relative density of the composite material increases significantly,and the relative density of the Ti6Al4V-0.01wt%B₄C composite material prepared with the laser energy density of 60 J/mm³reached the highest value of 99.49%.The microstructure of Ti6Al4V-xB₄C composites was analyzed,and it was found that in the 4 groups of Ti6Al4V-xB₄C composites,Ti and B₄C all reacted in situ,and the products were Ti B₂and Ti C.When the B₄C content is 0.01wt%and 0.1wt%,Ti B₂and Ti C generated in situ are mainly dispersed in the Ti6Al4V matrix in the form of small-size associative structures and independent particles,and the Ti6Al4V matrix structure is obviously refined;When the B₄C content increases to 1wt%and 10wt%,the Ti B₂and Ti C generated in situ mainly exist in the form of cluster-like associative organization and network-like associative organization.The grain refinement effect of Ti6Al4V is more obvious.But at the same time,the defects such as pores and cracks increase.The mechanical properties of Ti6Al4V-xB₄C composites were tested,The results showed that the microhardness of the Ti6Al4V matrix can be significantly improved by adding B₄C.When the B₄C content is 10wt%,the microhardness of the composite material reached the highest value of 790 HV,and the improvement rate reaches 120%;When the addition amount of B₄C is 0.01wt%and 0.1wt%,the static compression performance of the composite material is affected by the effects of fine-grain strengthening and dispersion strengthening,and the compressive strength and plasticity are significantly improved,the strength is increased by12.8%,and the plasticity is increased by 72.9%.But when the amount of B₄C added exceeds1wt%,the brittleness of the composite material will increase,and fracture will occur before the plastic stage;The addition of 0.01wt%and 0.1wt%of B₄C can also significantly improve the dynamic compression performance of the composite material,the dynamic compressive strength is increased by 14.4%,and the dynamic plasticity is increased by 52.2%.