Effect of heat treatment on microstructure and mechanical properties of extruded ZM61 magnesium alloy

Abstract

The effects of T5 and T6 heat treatments on the microstructure and mechanical properties of extruded Mg–6Zn–1M n alloy were investigated in the present study. The results showed that T5 and T6 treatments could markedly improve the strengths of extruded ZM61 alloy, and the precipitate strengthening effect of double aging was better than that of single aging. The precipitates formed in the T6 treatment were much finer and more dispersive than the ones in the T5 treatment, resulting in stronger precipitation strengthening effect. However, due to additional grain size refinement strengthening effect, the T5 treatment could improve ductility without sacrificing strength over the T6 treatment. Scanning electron microscopy observation and tensile test indicated that different cooling methods after extrusion, such as air cooling and water quenching, had no obvious influence on the microstructure and strengths of extruded and subsequent heat treated Mg–6Zn–1Mn alloys. In addition, the Mn element mainly existed as fine Mn phase particles, which were well dispersed in the matrix. Dispersed Mn particles could be found in rod-like [Formula: see text] precipitates, but not in the disc shaped [Formula: see text] precipitates.

Effect of aging treatment on fracture toughness in ZM61 magnesium alloy

“…It is observed that two kinds of precipitates formed during aging treatment. It has been reported [16][17][18][22][23][24] that the two precipitates are rod shaped b' 1 and plate shaped b' 2 precipitates, respectively. Most of the precipitates in single aged alloy are rod shaped b' 1 with a dimension of 100 nm in length and 10 nm in width.…”

“…[11][12][13][14][15] According to our previous researches, after T6 treatment (solution treatment and double aging), the yield strength (YS), ultimate tensile strength (UTS) and elongation of ZM61 could reach more than 340 MPa, 370 MPa and 5%, respectively. 16 The age hardening response of ZM61 alloy is mainly from Mg-Zn intermetallic compounds, rod shaped b' 1 precipitates are the key age hardening precipitates while extensive precipitation of plate shaped b' 2 phase causes overaging. 17,18 By reason of the method to estimate fracture toughness is difficult, high cost and always time consuming.…”

Thermodynamic analysis of the formation reaction of second phases in Mg–Zn–Mn–Sn–Nd alloys

“…1,2 However, low absolute strength and poor formability have become the bottleneck which constrains Mg alloys application. [3][4][5][6] Currently, many researchers have performed a role in the development of high-strength wrought Mg alloys. Alloying has been widely used as one of the most effective ways to develop new high-strength wrought Mg alloys.…”

Microstructure and tensile properties of as extruded and as aged Mg–Al–Zn–Mn–Sn alloy

“…5 Alloying addition is an effective method to improve the microstructure and mechanical properties of magnesium alloys. 6 Sn, as an additional element to magnesium alloys, is of great importance due to its cheap price and potential to develop mechanical properties. 7 This element forms thermally stable Mg 2 Sn phase with a face centre cubic structure.…”