The　aim　of　this　study　is　to　enhance　the　interfacial　bonding　strength　of　carbon　nanotubes　(CNTs)/AZ91　composites　by　heat　treatment　(HT).　Ternary　carbides　(Al2MgC2)　were　in　situ　formed　and　uniformly　dispersed　between　CNTs　and　AZ91　matrix　by　823K　heat　treatment　of　CNTs/AZ91　composites　for　12　h.　In　situ　synthesized　Al2MgC2　can　strengthen　the　interfacial　bonding　of　CNTs/AZ91　composites,　and　guarantee　an　effective　load　transfer　between　matrix　and　CNTs.　The　HT-CNTs/AZ91　composites　showed　outstanding　mechanical　properties　due　to　the　excellent　interface　enhancing　effect　of　Al2MgC2.　Compared　with　pure　AZ91　alloy,　HT-CNTs/AZ91　composites　exhibit　improved　ultimate　tensile　strength　and　0.2%　yield　strength　by　7%　and　22%　respectively.　©　2017　Trans　Tech　Publications,　Switzerland.