Transactions of Materials and Heat Treatment

Title：Influences of isothermal reciprocating upsetting-extrusion (RUE) on microstructure and mechanical properties at room temperature for Mg-Re-Zn alloy

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ClassificationCode：TG164.22

year,vol(issue):pagenumber：2021,46(3):126-130

Abstract：

Mg-9Gd-3Y-2Zn-0.5Zr alloy was subjected to four-pass isothermal reciprocating upsetting-extrusion (RUE) deformation experiments at the steady temperature of 420 ℃, and the change laws of microstructure and mechanical properties at room temperature of alloy during isothermal RUE process was studied. The research shows that with the gradual increasing of isothernal RUE passes, the dynamic recrystallization occurs, and the grain refinement effect is obvious. This is because that the stress concentration generated near the LPSO phase hinders the dislocation movement and generates dislocation accumulation to promote the dynamic recrystallization. After four passes of processing, the bulky phase discontinuously distributed at the grain boundary in the initial state of alloy becomes a small-size bulky phase uniformly distributed in the matrix and arranged along the extrusion direction. In the whole deformation process, the precipitated phase inside the alloy does not change significantly compared to the alloy in the initial state, which indicates that no new phase is generated during the whole deformation process. In addition, after four passes of isothermal RUE, the mechanical properties of alloy are significantly improved with the ultimate tensile strength of 327.70 MPa, the yield strength of 247.95 MPa and the elongation of 9.60% comparing to the alloy in the initial state, which is the result of the combined effect of dislocation multiplication, grain refinement strengthening and the second phase of LPSO strengthening.

Funds：

山西省自然科学基金资助项目 (201901D111176)；山西省重点研发计划 (201903D421036)

张思杨（1996-），女，硕士研究生 E-mail：736456527@qq.com 通讯作者：于建民（1974-），男，博士，教授 E-mail：minyu@163.com

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