Official Answer
Answer
Elgiloy is a 'super-alloy' used in medical implants (like heart valves or stents) due to its exceptional biocompatibility, high fatigue strength, and resistance to corrosion in bodily fluids. It has a high modulus of elasticity ($E \approx 190$ GPa) and can be heat-treated to very high hardness levels. For wave springs, Elgiloy provides a combination of high spring force and the ability to withstand billions of cycles without failure. Its resistance to 'pitting' and 'crevice corrosion' exceeds that of 316L stainless steel. The material is also non-magnetic, which is crucial for patients who may require MRI scans. Processing involves cold-working followed by a precipitation hardening cycle at approximately $480^{\circ}C$.
