Deformation Mechanisms of Nano-Porous Hexagonal Metals

Hexagonal materials such as Titanium or Magnesium are frequently applied for medical implants due to their low density. However, there are several challenges for such application: the mismatch to bone in terms of stiffness, and the poor formability of hexagonal metals, to name the two most prominent ones. The stiffness can be adjusted by use of porous materials, but the formability/ductility remains a limitation.

In this work, we explore the size dependent deformation mechanisms of hexagonal metals in order to identify structural dimensions where the increase in strength due to structural refinement allows for activaiton of additional deformation schemes, thereby increasing the ductility of the porous material.

Therefore, we study the influence of size on the deformation behavior of different sized samples in tension and compression by miniaturized in situ experiments in the SEM and TEM, in conjunction with detailed post mortem analysis of the sample microstructure. Below, a FIB fabricated single crystal Mg compression sample is shown before and after testing, along with a video of the corresponding in situ SEM compression experiment of the only 4 µm diameter specimen.

These micromechanical experiments in the SEM were complemented by quantitative in situ TEM compression experiments, as well as post mortem crystal orientation mapping in the SEM and TEM, respectively. The image analysis in conjunction with the mechanical data enabled to determine the competing behavior between prismatic slip and twinning.

 

The most significant insights related to this project are detailed in the publications linked to the bullet points below. Dokuments for academic purpose only can be found at the bottom of the page.

 

Acknowledgement: This work is supported by the FWF (I-1020: Deformation Mechanisms of Nano-Porous Hexagonal Metals) and the NRF in a joint call.