摘要
Mg-6Zn-x Ce(x = 0, 0.6, 1.0, 2.0) alloy ingots with diameter of 50 mm were extruded into bars with diameter of 12 mm at 300 ℃. The microstructures were analyzed by X-ray diffraction, optical microscopy, scanning electron microscopy and transmission electron microscopy, and mechanical properties were tested at room temperature. The results showed that major intermetallic composition in as-cast Mg-6Zn and Mg-6Zn-0.6Ce alloys was Mg_4Zn_7 phase, during extrusion Mg_4Zn_7 phase was dissolved into matrix and then precipitated as MgZn_2. In as-cast and as-extruded Mg-6Zn-1Ce and Mg-6Zn-2Ce alloys the major intermetallic composition was T phase. The microstructure of as-extruded alloy was refined due to complete dynamic recrystallization, the average grain size decreased with increasing Ce content, which were 12.1, 11.7, 11.0 and 10.0 mm, respectively. High density MgZn_2 precipitated in Mg-6Zn and Mg-6Zn-0.6Ce alloys. The broken T phase particles were distributed linearly along extrusion direction. Mg-6Zn-0.6Ce alloy exhibited a high yield strength of 226.3 MPa that was about 24 MPa higher than Mg-6Zn alloy. However, with increasing Ce contents, the strengths were decreased slightly because the effects of precipitation strengthening of MgZn_2 and solid solute strengthening of Zn were weakened though the strengthening effect of T phase was enhanced.
Mg-6Zn-x Ce(x = 0, 0.6, 1.0, 2.0) alloy ingots with diameter of 50 mm were extruded into bars with diameter of 12 mm at 300 ℃. The microstructures were analyzed by X-ray diffraction, optical microscopy, scanning electron microscopy and transmission electron microscopy, and mechanical properties were tested at room temperature. The results showed that major intermetallic composition in as-cast Mg-6Zn and Mg-6Zn-0.6Ce alloys was Mg_4Zn_7 phase, during extrusion Mg_4Zn_7 phase was dissolved into matrix and then precipitated as MgZn_2. In as-cast and as-extruded Mg-6Zn-1Ce and Mg-6Zn-2Ce alloys the major intermetallic composition was T phase. The microstructure of as-extruded alloy was refined due to complete dynamic recrystallization, the average grain size decreased with increasing Ce content, which were 12.1, 11.7, 11.0 and 10.0 mm, respectively. High density MgZn_2 precipitated in Mg-6Zn and Mg-6Zn-0.6Ce alloys. The broken T phase particles were distributed linearly along extrusion direction. Mg-6Zn-0.6Ce alloy exhibited a high yield strength of 226.3 MPa that was about 24 MPa higher than Mg-6Zn alloy. However, with increasing Ce contents, the strengths were decreased slightly because the effects of precipitation strengthening of MgZn_2 and solid solute strengthening of Zn were weakened though the strengthening effect of T phase was enhanced.
基金
Funded by the National Natural Science Foundation of China(No.51571086)
China Postdoctoral Science Foundation(No.2013M541973)
The Research Fund for Doctoral Program of Henan Polytechnic University(No.B2015-14)
