The results show the possibility to design CFRM composites with a combination of good to excellent properties including elastic modulus, tensile and flexural strength, fatigue and creep resistance. The new process employed has shown its capability to produce fibre composites with a high efficiency in relation to theoretical values. The choice of the matrix alloy, however, has a strong influence on properties. Conventional casting alloys like AA357 (Al-7%Si-based) or AA203 (Al-4%Cu-based) are not appropriate for achieving high composite strength in longitudinal direction. The development of new aluminium alloys for use as matrices is necessary. Promising candidates are solid solution hardenable alloys such as low alloyed Al-Cu or Al-Zn-Mg matrices. The favourable character of these composite materials opens up new possibilities in the selective fibre reinforcement of aluminium castings. With strength values of more than 200 MPa transverse to the fibres and in non-reinforced areas, these types of MMCs could match requirements of structural applications that are not possible with fibre reinforced polymers or carbon fibre reinforced metals.
Owing to its high design flexibility the newly developed precision casting route opens up new possibilities for the use of light weight metal matrix composites. Aluminium alloys with a continuous fibre reinforcement seem to be highly appropriate for structural and engineering applications with high requirements on load transfer and stiffness in both, static and dynamic loading conditions.
The proposed research project will modify the precision casting process regarded as a classic near-net-shape production technique, for the manufacture of long-fibre reinforced aluminium castings (MMC's). Alongside development of the process, the subsequent steps of materials testing and assessment, application and recycling will be investigated, to ensure integrated planning of the entire product cycle.
Primary performance aims are significantly enhanced strength and stiffness and reduced thermal expansion. In the area of materials testing and assessment, particular attention will be paid to the use of non-destructive test methods and applications-oriented mechanical testing techniques developed specifically for FRM's. Development of the recycling process will concentrate on means of separating and re-utilizing the matrix and the reinforcing elements. The main field of application will lie in the production of selective reinforced components for the civil aircraft and helicopter production, but there are also interesting potential applications in the automotive sector, in mechanical engineering and power station construction and in the sport and leisure industries.
The project embrace the following main areas of research :
1. Further development of the investment casting process for the manufacture of long-fibre reinforced castings using modified process steps for wax pattern fabrication, shell mould construction and casting.
2. Postprocessing with development of suitable heat treatment parameters and improved methods of corrosion protection.
3. Structural analysis, particularly of the fibre-matrix interface, using optical microscope, SEM and TEM.
4. Development of suitable mechanical test methods for determining strength, stiffness, fatigue and creep behaviour, taking applications-oriented requirements into account (multiaxial tests, elevated temperature tests, testing of real components etc.).
5. Development of a suitable non-destructive test technology employing X-ray microtomography with a resolution of less than 10 um.
6. Development of a technique for separating fibres and matrix, re-utilizing the recovered aluminium and investigating possible means of re-utilizing the recovered reinforcing material.
Following successful completion of the project research, extensive substitution options for aircraft manufacturing applications with cost savings up to 40% per component are predicted.
Funding SchemeCSC - Cost-sharing contracts
SW7 2BP London
6800 ET Arnhem
5600 AN Eindhoven
5600 MB Eindhoven