Microstructure and Mechanical Properties of As-Aged Mg-Zn-Sn-Mn-Al Alloys

Abstract

The microstructure and mechanical properties of as-aged Mg-6Zn-4Sn-1Mn-xAl (ZTM641-xAl, x = 0, 0.2, 0.5, 1, 2, 3 and 4 wt.%) alloys are studied in this paper. In terms of microstructure, the results reveal that the addition of Al mainly leads to the formation of the Al8Mn5, Al11Mn4, Al2Mg5Zn2 and Mg32(Al,Zn)49 phases. With increases in the addition of Al, the average grain size first decreases and then increases, while the undissolved phases increase. The average grain size of the ZTM641-0.5Al alloy is the smallest, and the single-aged and double-aged grain size is 14 μm and 12 μm, respectively. As for mechanical properties, with increases in the Al element, the strength decreases, and the elongation first increases and then decreases. The double-aged ZTM641-0.2Al alloy exhibits favorable mechanical properties at room temperature, and the UTS, YS and elongation are 384 MPa, 360 MPa and 9%, respectively. Further, the double-aged ZTM641-0.2Al alloy exhibits the comprehensive mechanical properties at 150 °C, that is, the UTS, YS and elongation are 212 MPa, 196 MPa and 29%, respectively, which is about 45% higher than that of the elongation of ZTM641. The ZTM641-xAl alloys exhibits mixed fracture at room temperature, and, with increases in the addition of Al, the fracture mechanisms of alloys are mixed fracture, ductile fracture and mixed fracture at 200 °C.

Study on the Microstructure of Mg-4Zn-4Sn-1Mn-xAl As-Cast Alloys

“…The results show that the grain sizes decrease and then increase with the increase in Al element content, and the addition of Al elements can promote the formation of second phases such as Al 8 Mn 5 , Al 11 Mn 4 , Mg 32 (Al,Zn) 49 , Al 2 Mg 5 Zn 2 , and MgZn. However, in this study, the Al-Mn phases possess an Al 3 Mn 2 structure, which is not consistent with that reported in the literature [46][47][48][49]. And the combination of Mn and Zn would be changed for the Al addition.…”

“…Secondly, it can be found that the α-Mn dispersoids disappear and are replaced by Al 3 Mn 2 particles. Ye, Hou, and Deng reported the Al 8 Mn 5 and Al 11 Mn 4 in the Mg-6Zn-4Sn-1Mn-xAl alloys [46][47][48][49]. However, no studies have been reported on the formation of the Al 3 Mn 2 phase in Mg-Zn-Sn-Mn-Al alloy.…”

“…Studies on the microstructure of Mg-6Zn-4Sn-1Mn-xAl (wt.%) alloys have been reported [46][47][48]. These studies focused on the second phase and properties of the extruded and aged states of the Mg-6Zn-4Sn-1Mn-xAl series alloys after homogenization heat treatment.…”

Influence of Al Addition on the Microstructure and Mechanical Properties of Mg-Zn-Sn-Mn-Ca Alloys

“…From Figure (a), we can see that the one-stage aged ZTM641-0.2Ca alloy has the highest strength, with the UTS and YS being 392 MPa and 365 MPa, respectively. According to our previous research [ 21 ], the UTS and YS of the one-stage aged ZTM641-0.2Al alloy are 382 MPa and 352 MPa, and the UTS and YS of one-stage aged ZTM641-0.5Al alloy are 350 MPa and 299 MPa. When 0.5% Al is added to the alloy, the strength and plasticity show a decreasing trend, while the UTS and YS are 365 MPa and 325 MPa, respectively.…”

“…When the alloy is deformed, the coordinating deformation ability of the alloy is poor, resulting in a decrease in the strength of the alloy. [21], the UTS and YS of the onestage aged ZTM641-0.2Al alloy are 382 MPa and 352 MPa, and the UTS and YS of one-stage aged ZTM641-0.5Al alloy are 350 MPa and 299 MPa. When 0.5% Al is added to the alloy, the strength and plasticity show a decreasing trend, while the UTS and YS are 365 MPa and 325 MPa, respectively.…”