The tailoring of material properties requires the design of the alloy composition and of the microstructure resulting from the manufacturing process. Also environmental constraints and new regulations constantly require the adaptation or revision of alloy compositions and consequently of the manufacturing processes. Thus, materials processing of cemented carbides has been revisited with alternative binders to Co or with less strategic metallic carbides than WC, in order to optimize sintering and microstructure and ultimately the mechanical properties. Additive manufacturing by selective melting required adapting the alloy compositions to the rapid cooling rates and conversely, it made it possible to design specific microstructures in connection with the process. Finally, it was shown that the design of alloy compositions was essential for obtaining metallic glasses and controlling their properties, as it was for controlling the biodegradability of magnesium alloys for medical implants.
Since the development of rapid cooling solidification techniques, bulk metallic glasses (BMG) have attracted much attention for industrial applications. Thanks to the amorphous structure and therefore the lack of defects linked to crystalline structures (e.g. dislocations, grains boudaries etc.), BMG exhibit peculiar properties. Among them, one can mention high strengh, good hardness or excellent micro moulding ability (down to a few micrometers) as well as appealing biocompatibility making them of particular interest for medical applications. Yet improvements in terms of properties are still numerus. In order to improve corrosion resistance, we have performed Nb micro-alloying on a ZrCoAl amorphous alloys. This greatly improved corrosion behaviour in saline solution, closing the gap with titanium alloys.
(left) schematic representation of the Nb micro-alloying, (right) polarisations curves of (i) ZrCoAl BMG, (ii) ZrCoAlNb BMG and (iii) TA6V. Thesis Eliott Guerin (2018-2021)
mise à jour le 20 novembre 2019