Strength increased by 40%: preparation results of new porous titanium alloy cold spray technology

What can porous titanium alloy materials do? How to make it? This can be answered by the latest 3D printing (cold spray) technology developed by the research team of Cornell University and MIT and other university cooperative projects. The research was published in the journal "Applied Materials Today." on November 9 this year under the title "Preparation of porous titanium alloys by supersonic impact 3D printing".
This picture shows the cells adhering to a titanium alloy made by cold spray 3D printing, which shows the biocompatibility of this material.
The basic concepts such as cold spraying and 3D printing are not repeated here because of the general knowledge structure of the readers of this official account. To put it simply, this technology mainly uses powder supersonic impact to form solid-state bonds to produce high-strength porous titanium alloys under conditions far below the melting temperature, and can further improve the mechanical properties through post heat treatment, and finally apply it In the field of orthopedic transplantation. As shown in FIG.
Normal metal 3D printing will result in large residual stress and poor mechanical properties due to the high temperature processing of powder melting and solidification layer by layer. Cold spray technology can make up for this defect. Usually the powder will choose an optimal speed between the critical speed (the speed at which dense solids are formed) and the erosion speed (overspeed will cause the powder to break and cannot be combined), and it will be launched through the nozzle. On the substrate. "Similar to painting, but 3D printing will accumulate more."
The research team used fluid mechanics calculations to determine a speed slightly lower than the critical speed of titanium alloy (about 600m/s), using high strain rate to dynamically print Ti-6Al-4V powder with a particle size between 45 and 106μm Finally, a porous structure material (apparent modulus 51.7±3.2gpa, apparent compressive yield strength 535±35mpa, porosity 30±2%) with 42% higher strength than other 3D printed titanium alloys was manufactured.
Although this process is technically called cold spraying, it does involve some heat treatment. When these particles collide and bond together, the researchers heat the metal to cause these components to diffuse into each other and settle down like a homogeneous substance.
The researchers mentioned, "If we use this porous structure to make implants and implant them in the human body, bones can grow in these pores and be biologically fixed." "This helps reduce the loosening of the implant. It’s a big deal. There are many patients who have to surgically remove the implant again, because the implant is loose and it will cause a lot of pain."
In addition to the orthopedic transplantation that the project focuses on, essentially any metal material that can withstand plastic deformation can benefit from this process. It brings many opportunities for larger-scale industrial applications such as construction, transportation and energy.