Biomedical Engineering Reference
In-Depth Information
Generally mechanical alloying consists of repeated fracture,
mixing, and cold welding of a ine blend of elemental particles,
resulting in size reduction and chemical reactions. The sintering
results in compacts, used for the next treatment, respective for the
pores formation. The compacts with relatively low density (90% of
the theoretical density) are attractive material for the electrochemi-
cal etching, due to the large volume of the grain boundaries, which
state the easy paths for the electrolyte penetration and diffusion. For
that reason the nanocrystalline compacts are etched fast and easy.
Figure 9.63
Mechanically alloyed Ti-6Al-4V after sintering and
electrochemical etching (a, b — different magniications);
for comparison is shown electrochemically etched bulk
microcrystalline sample (c) [29].
The electrolyte applied by Jakubowicz and Adamek [29]
contained H
3
PO
4
with small HF addition, enhancing dissolution [28]
and resulting in porous Ti-6Al-4V compacts (Fig. 9.63a,b). After
