锻压技术

等温往复镦粗-挤压对Mg-Re-Zn合金微观组织和室温力学性能的影响

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

作者：张思杨于建民张治民徐文龙贾蕾琛吴国琴王洪海

单位：1.中北大学材料科学与工程学院 2.西安近代化学研究所

关键词：Mg-Gd-Y-Zn-Zr合金等温往复镦挤晶粒细化微观组织力学性能

分类号：TG164.22

出版年,卷(期):页码：2021,46(3):126-130

摘要：

对Mg-9Gd-3Y-2Zn-0.5Zr合金在420 ℃恒定温度下进行了4道次等温往复镦挤变形实验，研究了等温往复镦挤过程中合金微观组织和室温力学性能的变化规律。研究表明:随着等温往复镦挤变形道次的逐渐增加，动态再结晶发生，晶粒细化效果明显，这是主要是因为LPSO相附近产生的应力集中阻碍了位错运动，产生位错堆积，从而促进了动态再结晶。4道次加工后，初始态合金中在晶界处不连续分布的大块状相转变为在基体中均匀分布、沿挤压方向排列的小尺寸块状相。在整个变形过程中，合金内部的析出相较初始态合金并未明显变化，这表明在整个变形过程中没有新相生成。此外，经过4道次等温往复镦挤加工，合金的力学性能较初始态合金得到了显著提高，其极限抗拉强度、屈服强度和伸长率分别为327.70 MPa、247.95 MPa和9.60%,这是位错增殖、细晶强化、第二相LPSO相强化综合作用的结果。

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.

基金项目：

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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