Microstructure evolution and mechanical properties of Mg−Gd−Zn alloy with and without LPSO phase processed by multi-directional forging  

含与不含LPSO相的Mg-Gd-Zn合金多向锻造过程中的显微组织演变及力学性能

作　　者：Jing-yi HUANG Yao-ling LIU Yu-xiang HAN Ying-chun WAN Chu-ming LIU Zhi-yong CHEN 黄静怡;刘窈伶;韩宇翔;万迎春;刘楚明;陈志永(中南大学材料科学与工程学院,长沙410083;中南大学轻合金研究院,长沙410083;湖南镁宇科技有限公司,岳阳414000)

机构地区：[1]School of Materials Science and Engineering,Central South University,Changsha 410083,China [2]Light Alloy Research Institute,Central South University,Changsha 410083,China [3]Hunan Meiyu Science and Technology Co.,Ltd.,Yueyang 414000,China

出　　处：《Transactions of Nonferrous Metals Society of China》2025年第4期1075-1091,共17页中国有色金属学报(英文版)

基　　金：the financial supports from the Key Research and Development Program of Hunan Province,China(No.2023GK2020)。

摘　　要：The homogenized Mg−5.6Gd−0.8Zn(wt.%)alloys were treated with water cooling and furnace cooling to obtain specimens without and with the 14H long-period stacking ordered(LPSO)phase.Subsequently,multi-directional forging(MDF)experiments were carried out.The microstructure and mechanical properties of different regions(the center,middle and edge regions)in the MDFed alloys were systematically investigated,and the effect of LPSO phase on them was discussed.The results show that the alloys in different regions undergo significant grain refinement during the MDF process.Inhomogeneous microstructures with different degrees of dynamic recrystallization(DRX)are formed,resulting in microhardness heterogeneity.The alloy with the LPSO phase has higher microstructure homogeneity,a higher degree of recrystallization,and better comprehensive mechanical properties than the alloy without the LPSO phase.The furnace-cooled alloy after 18 passes of MDF has the best comprehensive mechanical properties,with an ultimate compressive strength of 488 MPa,yield strength of 258 MPa,and fracture strain of 21.2%.DRX behavior is closely related to the LPSO phase and deformation temperature.The kinked LPSO phase can act as a potential nucleation site for DRX grains,while the fragmented LPSO phase promotes DRX nucleation through the particle-stimulated nucleation mechanism.对Mg-5.6Gd-0.8Zn(质量分数,%)合金进行均匀化水冷和均匀化炉冷两种热处理工艺,得到无14H长周期有序堆积(LPSO)相和有14H LPSO相的合金,随后对两种合金进行多向锻造。系统研究了多向锻造过程中合金不同区域(中心、次边部和边部)的显微组织和力学性能,并讨论了LPSO相对其影响。结果表明:在多向锻造过程中,合金的晶粒明显细化,各区域形成动态再结晶程度不同的不均匀组织,导致显微硬度的不均匀性;与不含LPSO相的合金相比,含LPSO相合金的再结晶程度和组织均匀性更高,综合力学性能更好。经18道次多向锻造的炉冷态合金的综合力学性能最佳,其抗压强度为488 MPa,屈服强度为258 MPa,断裂应变为21.2%。此外,多向锻造过程中的动态再结晶行为与LPSO相和锻造温度密切相关。扭折的LPSO相可以作为动态再结晶的潜在形核位点,而破碎的LPSO相则通过粒子刺激形核机制促进动态再结晶。

关 键 词：Mg−Gd−Zn alloy multi-directional forging LPSO phase twinning kink dynamic recrystallization 

分 类 号：TG146.2[一般工业技术—材料科学与工程]