The influence ofdefectbandonthetensilefailureinhighpressurediecastingofAM60Bmagnesium
alloy wasstudiedby in situ scanning electronmicroscope.Resultsshowedthatthesizeanddistribution
of theexternallysolidified crystals(ESCs)hadasignificant influence onthetensilebehaviorinducedby
defect bandinthespecimen.InthespecimenwithfewESCs,thecrackwouldinitiateatthegas-
shrinkage poreinthecenterofthespecimen.Furthercrackpropagationatthedefectbandwashindered
by thesurroundingdensemicrostructure,andtheeffectofdefectbandonthetensilefailurewasjust
reducing theefficient forcebearingarea.InthespecimenwithlargeandcomplexESCs,themicro-
structure aroundthedefectbandwouldbecomecoarseandcomprisedoflargeporositieswithcomplex
morphology.Thedefectbandwouldactascrackinitiationsiteandfacilitatethecrackpropagationto
both centerandsurfaceofthespecimen,leadingtothe final fracture.