Damping mechanisms of Fe - Mn alloy with (γ + ε) dual phase structure

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