Anas-castmagnesiumalloywithhighAlcontentMg15Alwassubjectedtoequal-channelangularpressing(ECAP)throughadiewithanangleofφ=90?at553KfollowingrouteBc.Itisfoundthatthenetworkβ-Mg17Al12phasesintheas-castMg15Alalloyarebrokenintosmallblocksanddisperseduniformlywithincreasingnumbersofpressingpasses.Moreover,manynano-sizedMg17Al12particlesprecipitateintheultra-fineα-Mgmatrix.Thegrainsareobviouslyrefined.However,thegrainstructureisinhomogeneousindifferentareasofthealloy.Theaveragesizeoftheprimaryphaseα-Mgisreducedtoabout1μmwhilegrainsofaround0.1-0.2μmareobtainedinsometwo-phaseareas.WithadditionalECAPpasses(upto8),coarseningofthegrainsoccursbydynamicrecovery.RoomtemperaturetensiletestsshowthatthemechanicalpropertiesofMg15Alalloysaremarkedlyimprovedafter4ECAPpasses.Theultimatetensilestrengthandelongationtofailureincreasefrom150MPato269.3MPaandfrom0.05%to7.4%,respectively.Comparedwiththatafter4passes,theelongationtofailureofthealloyincreasesbutthestrengthofthealloyslightlydecreasesafter8ECAPpasses.FracturemorphologyoftheECAP-processedalloyexhibitsdimple-likefracturecharacteristicswhiletheas-castalloyshowsquasi-cleavagefractures.
