Damping mechanisms of Fe–Mn alloy with ( γ + ɛ ) dual phase structure

The objective of the present study is to propose damping mechanisms for Fe–Mn alloys containing austenite (face centred cubic) and ɛ martensite (hexagonal close packed), and to analyse the individual contribution of damping mechanisms to the total damping capacity of an Fe–17 wt-%Mn alloy with respect to volume fraction of ɛ martensite. On the basis of substructural characteristics of γ and ɛ phases, it is suggested that damping mechanisms of Fe–Mn alloys with (γ + ɛ) dual phase structures involve stress induced movement of various boundaries such as stacking fault boundaries in austenite and ɛ martensite, ɛmartensite variant boundaries, and γ/ɛ interphase boundaries. The damping capacity of the Fe–17Mn alloy increases with increasing ɛ martensite content. The quantitative analysis shows that in the as quenched state, the ɛ martensite phase is responsible for a major part of the damping capacity.