A novel cost-effective process for the fabrication of AI-MMCs with improved mechanical properties for aerospace and other applications has been developed, using the in-situ creation of the reinforcing TiB2 particles by a reaction of the components in an aluminium melt. After solidification the fine particles (size: 1-2 mu m) remain homogeneously distributed in the aluminium alloy (2xxx and 7 xxx series) providing the desired increase of stiffness and suffcient ductility compared to the unreinforced alloy.
For practical application various secondary processing, such as casting, thixoforming, extrusion, and forging, was performed on the material in order to test the fabricated prototype components for their relevant mechanical properties and wear resistance.
Compared to conventional aluminium alloys, the addtion of only 5 vol.% of TiB2 has produced a significant improvement of the strength properties, e.g. an increase of Young`s modulus (+15%), ultimate tensile strength (+20%), and yield strength (+30%). At this stage, porosity and impurities limit a further improvment.
Different demostrator parts (seat track for aircraft, helicopter blade sleeve, conrod for automotive engine) have been manufactured and characterised in order to evaluate in-serivce properties. The obtained results clearly indicate the material`s promising capabilities, but for aerospace industry the improvement of the material achieved
so far is still not sufficient to meet the high requirements for structural parts.
Thus, a further process improvment, in particular clearness of the material and further increase of reinforcement volume percentage, will be the key issue of a future project to reach the areospace requirements.
The ISRPAM project was funded by the European Community under the Brite/EuRam III programme (BE 95-1902).