LAUSR

Abstract The precipitation behavior of Mg-8Al-2Sn-1Zn (ATZ821) alloy was investigated. Sn addition to the AZ81 alloy greatly influenced the initial precipitation behavior in the following two aspects: (i) the segregation of Sn solutes at the interface of Mg17Al12 via Sn partitioning induced during the growth of Mg17Al12 and (ii) high interfacial energy at the edge-tip of growing Mg17Al12. According to the hardness profile and detailed microstructural analyses of ATZ821 cast samples artificially aged at 453 K for different times, it was confirmed that the initial precipitation of Mg17Al12 was delayed due to Sn partitioning at the interface, and all Mg2Sn without exception was nucleated at the edge-tip of pre-existing Mg17Al12 precipitates on the basal planes. In addition, a selected area diffraction pattern analysis confirmed that α-Mg, Mg17Al12, and Mg2Sn had the following orientation relationship: ( 0001 ) α // ( 110 ) M g 17 A l 12 , [ 1 2 ¯ 10 ] α // [ 1 ¯ 11 ] M g 17 A l 12 and ( 0001 ) α // ( 022 ) M g 2 S n , [ 1 2 ¯ 10 ] α // [ 1 1 ¯ 1 ] M g 2 S n .