摘要
通过多道次热旋锻,成功制备了AZ61镁合金棒丝材,经细晶强化及纳米级颗粒强化显著提高了AZ61镁合金强度,并讨论了动态沉淀析出机理。结果表明:旋锻AZ61镁合金平均晶粒直径约为8μm,YS为302 MPa,UTS达376MPa,具有中等延伸率(7%)。纳米级沉淀相在旋锻变形过程中动态析出,这些沉淀相包括:晶内析出直径50~140 nm的球形β-Mg17Al12相(体积分数约6.5%)、平均直径10nm的球形Al6Mn相。大量细小纳米级第二相动态析出的机理为:旋锻是塑性变形-静态时效-塑性变形-静态时效交替进行的高频(锻打频率通常在1500~6000次/min)脉冲式热力加工过程。塑性变形产生的位错、空位等缺陷,为第二相析出提供了大量优先形核位置。并且每一脉冲周期中静态时效的时间很短(约为0.05 s数量级),所以析出的第二相不会长得过大。
The AZ61 magnesium alloy sticks and wires were prepared through multi-step hot rotary swaging,and the strength of AZ61 alloy was enhanced by grain refinement and dynamic precipitation during rotary swaging process.The dynamic precipitation mechanism during hot rotary swaging was also discussed.The results show that the rotary swaged AZ61 alloys exhibit a high YS of 302 MPa,a high UTS of 376 MPa and an elongation of 7%.The means grain size in rotary swaged AZ61 alloy is 8μm.The dynamically precipitated nanophases during rotary swaging process of AZ61 alloy include spherical Mg17Al12 particles(average size of 110 nm,~6.5 vol%)and spherical Al6 Mn particles(average size of 10 nm).The dynamic precipitation mechanism during rotary swaging process is as follows:rotary swaging is a high-frequency pulse forging process(the pulse forging frequency is between 1500 and 6000 strokes per min)during which plastic deformation intervals alternate with aging intervals.These crystal defects produced during plastic deformation such as dislocations and vacancies provide a large amount of nucleation sites for precipitation.The aging interval during each pulse period is as short as 0.05 s and hence the dynamic precipitate phases do not grow to a very large size.
作者
荣莉
聂祚仁
梁霄鹏
Rong Li;Nie Zuoren;Liang Xiaopeng(Beijing University of Technology,Beijing 100124,China;Central South University,Changsha 410083,China;College of Materials Science and Engineering,Beijing University of Technology,Beijing 100124,China)
出处
《稀有金属材料与工程》
SCIE
EI
CAS
CSCD
北大核心
2020年第10期3479-3483,共5页
Rare Metal Materials and Engineering
基金
国家自然科学基金创新研究群体项目(51621003)
中南大学有色金属材料科学与工程教育部重点实验开放课题(2019KFKT-02)。
关键词
镁合金
热变形
旋锻
析出强化
力学性能
magnesium alloy
hot deformation
rotary swaging
precipitation strengthening
mechanical properties
