Research on powder injection molding of Ti6Al4V alloys for biomedical application

Titanium and titanium alloys show the fantastic performances because of the high specific strength, low elastic modulus, good corrosion resistance, and excellent bio-compatibility. However, the application of titanium and titanium alloys is restricted due to the poor machinability. By integrating the advantages of traditional powder metallurgy and plastic injection molding technology, the metal injection molding (MIM) of titanium and titanium alloys overcomes the disadvantages of traditional machining and molding process. The parts of titanium and titanium alloys in complex structures are near net-shape manufactured by MIM in low-cost mass production, which increases the material utilization ratio. In this paper, the water soluble binder and spherical Ti6Al4V powders with particle size of 16 μm and 22 μm were employed to prepare the feedstock and specimens. An optimum process of atmosphere thermal debinding combined with vacuum sintering was determined by a series of experiments. In the results, the specimens with particle size of 16 μm fail to meet the surgical implant requirements for titanium and titanium alloys. In contrasts, the specimens with particle size of 22 μm demonstrate the properties as the relative density of 96.8%, ultimate tensile strength of 880 MPa, yield strength of 830 MPa, plastic elongation of 13.2%, oxygen mass fraction of 0.195%, nitrogen mass fraction of 0.020%, carbon mass fraction of 0.022%, meeting the surgical implant requirements for titanium and titanium alloys.