Unidirectional Solidification of Eutectic Cast Iron

Abstract

High intrinsic damping in alloys finds many applications in the elimination of unwanted vibrations and reduction of acoustic noise. The increasing interest in these materials has resulted in the development of a new class of engineering alloys, the HIDAMETS (high-damping metals), specifically tailored for use in vibration-resistant structures. Numerous different physical mechanisms (usually controlled by the alloy microstructure) can be responsible for the level of internal friction or damping in a candidate alloy for a particular application. Consequently, alloy selection depends mainly upon the conditions to be encountered in service, i.e. temperature, frequency of vibration, amplitude of vibration, magnetic field, etc. Characterization of the internal friction in high damping alloys is described and some of the mechanisms involved are discussed. Results obtained for two different alloys are presented. The first is a commercial Mn-Cu alloy used for marine propellers and the second is a die-cast Zn-Al alloy with possible application in the automotive industry.