In thispaper,threetypesofsand-castingM2052alloyssubjectedtodifferentheattreatmentshavebeen
designed andpreparedinordertoinvestigatetherelationshipbetweenMnsegregationanddamping
capacity usingdynamicmechanicalanalysis,opticalmicroscopy,X-raydiffraction,scanningelectron
microscopy,andenergydispersivespectroscopy.Theresultsshowthatdampingcapacityhasacrucial
dependence ontheMnsegregationinas-castM2052alloy.Theoriginalas-castalloywithoutsubsequent
heat treatmentshowsitsinternalfriction(Q
1) is1.5210
2 at astrainamplitudeof γ¼210
4, while
a remarkableenhancement(2.610
2) ofQ
1 can beobtainedbyageingoftheas-castalloyat435 °C
for 4h.ThisismainlyascribedtothefurtherformationofnanoscaleMnsegregationintheMndendrites
(so-called Mnmacrosegregation)byspinodaldecompositionduringtheageing.Onthecontrary,per-
forming theadditionalhomogenizationtreatmentat850 °C for24hpriortotheageingat435 °C for4h
for theas-castM2052alloycanresultintheobviousreductionofdampingcapacity(only6.510
3 for
Q
1), whichiscloselyassociatedwiththedistinctdecrementoflatticedistortionof γ′-Mn duringf.c.c-f.c.
t phasetransformationcausedbyweakeningofMnsegregationatthemacro/nano-scale.