Microstructure and mechanical property of high strength Mg–Sn–Zn–Al alloys

Abstract

This paper aims to reveal the microstructure and mechanical properties of as-cast and hot-rolled Mg–Sn–Zn–Al based alloys. Three alloys, Mg–5Sn–2Zn (TZ52), Mg–5Sn–2Zn–2Al (TAZ522) and Mg–5Sn–5Al–1Zn–0.2Mn (TAZM5510) alloys were studied. The results revealed that the as-cast alloys showed fine dendritic structures. The TAZM5510 alloys exhibited moderate yield strength of 98 MPa with good elongation of ∼15%, which was comparable to several commercially used Mg die-castings. Mechanical properties were significantly improved after multi-pass rolling. The TZ52 sheet showed a high yield strength of 277 MPa with excellent ductility exceeding 30%, and the TAZM5510 sheet exhibited the highest tensile strength of 386 MPa while keeping desirable elongation of 16.6%. These sheets are termed as strong and ductile Mg–Sn–Zn–Al wrought alloys.

Microstructure, Texture and Mechanical Properties of Mg-6Sn Alloy Processed by Differential Speed Rolling

“…As a result of ageing treatment at 150-200 °C, Mg2Sn phase precipitates are formed in the shape of laths or short rods lying on the basal plane [42,43]. After annealing or plastic deformation at a higher temperature, the spherical or polygonal-shaped precipitates are rather formed [16,17], which can be observed in our work as well (see the inset in Figure 3d). Mg2Sn particles were also present in the as-rolled sheets.…”

“…The intensity of basal texture gradually decreased from 8.2, multiples of random distribution (MRD) for R = 1 to 8.0, 7.3 and 5.0 MRD for R = 1.25, 2 and 3, respectively. The spread of (0002) and (11)(12)(13)(14)(15)(16)(17)(18)(19)(20) poles became more significant with higher speed ratio. This corresponded to the higher fraction of grains with a tilted c-axis from the ND observed in the IPF maps (represented by the purple and yellow colors).…”

“…A predominant basal texture (0002)//ND also developed in the Mg-6Sn sheets. Since the EBSD measurements of the as-rolled sheets were performed on the RD-ND plane, the two dominant orientations of grains visible on the IPF maps in Figure 1 are (10-10) and (11)(12)(13)(14)(15)(16)(17)(18)(19)(20) represented by blue and green color, respectively. The (0002) and (11)(12)(13)(14)(15)(16)(17)(18)(19)(20) pole figures corresponding to this RD-ND plane are shown in Figure 5.…”

“…Theoretical assumptions have been proved by some researchers for a dilute (up to 1 wt.%) [ 11 , 12 , 13 , 14 ] as well as higher Sn contents (5–8 wt.%) [ 15 , 16 , 17 ]. The extruded and hot rolled Mg-0.4Sn-0.7Y alloy sheets investigated by Wang et al [ 12 , 13 ] exhibited high ductility (around 33 and 32%, respectively) which has been attributed to the significant texture weakening and basal texture splitting.…”

“…Zeng et al [ 11 ] confirmed that the rollability of solutionized Mg-Sn alloys (with varying Sn addition from 0.5 to 3.5 wt.%) and the ductility of as-extruded Mg-Sn sheets increase with increasing amount of Sn. Higher Sn content (5–8 wt.%) is still sufficient to obtain Mg alloy with a good combination of strength and formability [ 15 , 16 , 17 ]. Yoon and Park [ 15 ] observed that Mg-Sn-based alloys (TAZ541, TAZ711, TAZ811) exhibit superior forgeability at elevated forming temperature as compared to conventional Mg-Al-Zn alloys (AZ61, AZ80).…”