An important physical property of an alloy is its damping capacity in response to an imparted mechanical force. High damping in iron-ruthenium alloys is closely linked to the amount of ε martensite present.

Scientists at Yonsei University, Seoul, Korea, have investigated the damping capacity of iron-ruthenium alloys, containing 25 and 13 per cent Ru at room temperature, using samples processed to contain various amounts of ε martensite (H.-C. Shin, J.-H. Jun and C.-S. Choi, Scr. Mater ., 2000, 42, (10), 981–986).

Fe-13% Ru, which undergoes a γ→α′ martensite transformation to give α′ single phase, showed poor damping capacity. Fe-25% Ru undergoes a γ→ε martensite transformation and has high damping capacity, dependent on the strain amplitude. For Fe-25% Ru, damping capacity increases with increasing E martensite content at < 3 × 10⁻⁴ strain amplitude. At strain amplitude > 4 × 10⁻⁴ it reached a peak for a volume fraction of ∼ 42 per cent of ε martensite. Stacking fault boundaries inside the ε martensite plates act as damping sources.