Lower Cost Materials for Stiffness Driven Aerospace Applications

The usefulness of Aluminum-Beryllium alloys in high stiffness, weight constrained applications has been demonstrated in a number of aerospace applications.  However, the high cost of the traditional powder metallurgy process has prevented the wide-spread use of Al-Be alloys.  Lower cost options for stiffness driven applications include investment cast Al-Be and Al-SiC metal matrix composites.  Investment cast Al-Be (193 GPa)  and Al-SiC composites (140 GPa) can offer stiffness values close to that of traditional Al-Be alloys (193 GPa) at a significant cost reduction.  In investment casting, the reduction is from reduced processing steps compared with a powder metallurgy derived product, a decrease in the amount of required machining, and a reduction in material usage.   Al-SiC composites benefit from a significant reduction in material costs. This paper compares the cost and properties of investment cast Al-Be and Al-SiC composites with traditional Al-Be, Ti and Al.