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Lecture

Packing changes of Ti nanoparticles in sintering from atomic simulations

Wednesday (06.11.2019)
09:55 - 10:15
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There is a continuous challenge in searching for artificial materials used for dental and orthopedic implants to replace diseased tooth, bone or even the joints inside the human or animal body. Pure titanium (Ti) has be used as raw materials in orthopedic prosthesis fabrication owing to its excellent properties including biocompatibility, adequate strength, corrosion resistance in the living environment, and no toxicity to human body. This has created a need to not only improve mechanical properties of the pure titanium to a level comparable with other Ti alloys, but also reduce stress shielding from the mismatch of elastic modulus between them and natural bones, which simultaneously retaining the purity of the metal. Ti implants with porous structure would be a clinically alternative option in order to match the mechanical properties of bone and increase integration, and the porous structure can offer space for bond regeneration without the aid of additional coating. Thus, the design and development of Ti products should have an overall consideration of processing-structure-property-performance combinations.

Until now, nano-sized particles have been used in the additive manufacturing (AM) processes. The shape and structural evolution of sintering particles has important consequences for the morphology-compact or ramified-depends, thus leading to whether or not to obtain a smooth, uniform structure and composition distribution of the products. The knowledge about the size dependence of packing changes for these nanoparticles in sintering, should be provided from atomic movements and rearrangements accounting for the temperature effect.

Atomic simulations using an embedded atom method (EAM) potential are performed to explore the microscopic details of packing changes of unsupported titanium nanoparticles in sintering. The interparticle distances between contact particles and contact facets are of significance in the packing changes with different particle size. Several analytical tools are used to demonstrate the changes in the connection regions and interior of the sintered particles.

 

Speaker:
Dr. Lin Zhang
Northeastern University