Abstract
Ongoing investigations have highlighted Mg-alloys as highly suitable for powder metallurgy (PM) processing regarding medical and lightweight 3C applications. In particular, metal injection moulding (MIM) possesses high potential for near net shape mass production of small sized and complex shaped parts. Previous developments have been conducted successfully by pressing and sintering, as well as MIM processing using pure Mg and Mg-Ca alloys. However, aiming towards medical and other applications more complex alloys are of great interest. Therefore, conventional Mg alloys like AZ81 and a quaternary Mg-RE-Zn alloy are tested for their implementation into the MIM process in this work. Using AZ81, tensile strength of 215 MPa and elongation around 5% was achieved with a reduced sintering time of 4 hours in contrast to 64 hours for Mg and Mg-0.9Ca. In addition, the possibility of simplifying the crucible setup and omitting the getter material are highlighted.
MIM of Mg-alloys possesses a high potential for the economic mass production of small sized and sophisticated shaped implant parts, as well as, other applications in an industrial scale.
Using sintering technique, no coarsening effect is reported. Hence sintering of Mg enables the production of small parts with very small grain size. In comparison, cast techniques of Mg-alloys are suffering from coarse microstructure.
The challenge of sintering magnesium is its high affinity to oxygen and its high vapor pressure. Oxygen affinity means that Mg is able to reduce stable oxide ceramics like e.g. alumina or zirconium oxide. This limits the usage of furnace high temperature materials. Hence, the manageability of these material skills is an outstanding challenge and can be performed by the researcher from the Helmholtz-Zentrum Geesthacht.
