ThediffusionbondingofAZ3\BMgalloyandQ235steelwasinvestigatedwithaZn-5AIalloyasinterlayerandunderdifferentholdingtimerangingfrom3to1200s.Themicrostructureandphasecompositionsofbondedjointswerecharacterizedbyscanningelectronmicroscopy(SEM),energydispersivespectrometer(EDS)andX-raydiffraction(XRD)methods.TheshearstrengthofMgalloy/steeljointswasmeasuredbytensiletester.Itwasfoundthatthemicrostructureofbondedjointsevolveddramaticallyalongwiththeprolongationofholdingtime.Undertheholdingtimeof3s,themainpartofjointwascomposedofMgZn2phaseanddispersedAl-richsolidsolutionparticles.Whenincreasedtheholdingtimemorethan60s,theexcessivesolutionofAZ3\Bintotheinterfacialreactionarealedtotheformationofcoarsephaseandeutecticmicrostructure,andalsothecomplexFe-AlandMg-Al-ZnIMCsattransitionlayerclosedtoQ235steelside.Accordingtothetensiletestingcharacterizations,thejointsobtainedunderholdingtimeof3sexhibitedthebestshearstrengthof84MPa,andthefractureoccurredattheintermediarypartofjointwheretheflexibleAl-richsolidsolutionparticlescouldhelptoimpedethemicrocrackpropagations.Withprolongingtheholdingtimeto600s,theshearstrengthofjointswasdeterioratedenormouslyandthefracturepositionwasshiftedtothetransitionlayerpartclosedtoQ235steel.
