Microstructure And Properties Of Ti-3Cu Alloy Fabricated By Selective Laser Melting

Ti-Cu alloy has been widely concerned in the field of biomedical implant materials for its excellent mechanical and biocompatibility.Ti-Cu alloy can be prepared by Selective Laser Melting（SLM）,which can form complex metal parts and avoid subsequent difficult machining operations.In this study,Ti-3Cu alloy was prepared by SLM,and the effects of SLM process parameters on the density,surface morphology,hardness and microstructure of Ti-3Cu alloy,the process parameters of SLMed Ti-3Cu alloy were investigated,and the microstructure,mechanics,electrochemical and antibacterial properties of SLMed Ti-3Cu alloy were characterized.SLMed Ti-3Cu alloy with good mechanical properties,corrosion resistance and antibacterial properties was prepared under the optimum technological parameters.The main research contents and conclusions are as follows:（1）The technological parameters of SLMed Ti-3Cu alloy were explored.The results shows that when the thickness of the SLMed Ti-3Cu alloy decreases from 50μm to 30μm,the connection between the layers becomes more compact,the porosity decreases,and the microstructure becomes more uniform.The density of the SLMed Ti-3Cu alloy increases from 99.20%to 99.34%,and finally P=180 W,v=1000 mm/s,t=30μm were selected as the optimal process parameters.（2）The microstructure and mechanical properties of SLMed Ti-3Cu alloy were investigated.The results show that the grain size of SLMed Ti-3Cu alloy obtained by fast cooling is smaller than as-forged Ti-3Cu,resulting in solid solution strengthening.The nano-sized Ti₂Cu alloy is entangled with dislocation.The yield strength,tensile strength and elongation of the alloy are 807 MPa,901 MPa and 10.3%,respectively.Compared with as-forged Ti-3Cu,the yield strength and tensile strength of the alloy can be increased twice by adjusting the process parameters of SLM without significantly reducing the plasticity.The strength of SLMed Ti-3Cu alloy increases and the elongation decreases gradually with the aging time.The maximum strength of SLMed Ti-3Cu alloy reaches when it is aged at 400℃for 8 h,and the yield strength,tensile strength and elongation are 993 MPa,1077 MPa and 5.4%,respectively.（3）The electrochemical properties of SLMed Ti-3Cu alloy were evaluated in simulated body fluid environment,and the antibacterial properties of SLMed Ti-3Cu alloy against Streptococcus mutans and Porphyromonas gingivalis were explored.The results show that the charge transfer resistance of SLMed Ti-3Cu alloy is twice that of CP-Ti,and SLMed Ti-3Cu alloy has better corrosion resistance than CP-Ti.When the co-culture time of SLMed Ti-3Cu with Streptococcus mutans and Porphyromonas gingivalis was extended from 24 h to 72 h,the antibacterial rate increased from 45.0%and 54.5%to 62.8%and 68.6%,respectively.With the extension of co-culture time,the bactericidal effect of SLMed Ti-3Cu material on both bacteria became more and more obvious.SLMed Ti-3Cu effectively inhibits bacterial adhesion to its surface,reduces surface biofilm formation,and plays a bactericidal role by destroying bacterial cell membranes.