Due to its excellent physical properties and resistance to infection, titanium alloys are a prime choice for the manufacture of orthopedic devices such as knee/hip implants. The team found that using titanium and tantalum powders with interesting properties could 3D print customized implants with better stress absorption. So far, researchers have used the selective laser melt (SLM) technique and titanium-aluminum powder to 3D-print biological prototypes. SLM technology usually USES high-power lasers to build 3D objects layer by layer based on computer design models. But because aluminum has a long history of damaging effects on human nerves, scientists hope to find other materials to replace it.
In theory, titanium and tantalum alloys are perfectly fine because both metals are biocompatible and their mechanical properties are due to pure titanium. But tantalum has a very high melting point (more than 3, 000 degrees Celsius), which means it is not economically feasible to turn titanium into a spherical metal powder that can be used for SLM technology. The tantalum powder commonly used in the market is usually a long coarse particle formed by gas atomization.
To overcome this problem, the team mixed the rough tantalum powder with another off-the-market micro-spherical titanium powder. After mixing the two materials for half a day, they observed that the mixture could be laid more evenly, making it easier to use with SLM technology. Microscope experiments revealed that the titanium's spherical shape remained after mixing, which was key to the mixture's success in 3D printing.
The researchers expect the titanium-tantalum alloy to reduce the "stress blocking" effect, in which the implant is too hard to give enough mechanical stimulation to neighboring bones, leading to osteoporosis. "These alloys are specifically designed for skeletal applications and may even show some shape memory after deformation.