Improvement of Thermal Stability and Evaluation of Fatigue Behavior of an Ultra fine-Grained Al-Mg-Sc Alloy Using ECAE

利用 ECAE 提高超细晶 Al-Mg-Sc 合金的热稳定性并评估疲劳行为

基本信息

批准号：
14550652
负责人：
MONZEN Ryoichi
金额：
$ 1.73万
依托单位：
Kanazawa University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2003
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-14550652/
关键词：
Al-Mg-Sc alloy ECAE thermal stability ultra fine grain fatigue behavior dislocation structure coherent Al_3Sc precipitate particle

项目摘要

The microstructure evolution of an ultrafine grained Al-3wt%Mg-0.2wt% Sc alloy produced by equal channel angular pressing during annealing at 573 K or 623 K has been examined. Annealing at 623 K for a short time caused complete recrystallization of the ultrafine grains. The structure development at 573K can be divided into three stages as follows :(1)Initial stage (〜30min). The hardness decreases rapidly with annealing time and the grain size increases from 300 to 600 nm. The dislocation, density becomes lower by recovery, The grain growth and the reduction in dislocation density bring about the decrease in hardness.(2)Intermediate stage (30min〜11h). The hardness increases and the grain size remains almost unchanged. Fine precipitated Al_3Sc particles are formed in grain interiors. These particles cause primarily the increase of the hardness. The small Al_3Sc particles on grain boundaries pin grain boundaries and restrict their migration.(3)Later stage (11h〜). At this stage, again the … More grain growth occurs and the hardness decreases. This is because the pining force and the particle strengthening gradually decrease with increasing the Al_3Sc particle size. From the linear relationship between the grain size and Al_3Sc particle radius, it is concluded that the grain growth is controlled by the rate of coarsening of the Al3Sc particles.Plastic-strain-controlled low-cycle fatigue tests of an Al-Mg-Sc alloy containing Al_3Sc particles with average diameters 4 nm and 11nm were carried out. The results and conclusions are summarized as follows :(1)Specimens with Al_3Sc particles of 4nm in diameter show cyclic softening at higher plastic-strain amplitudes (ε_<pl>【greater than or equal】1×10^<-3>). All other specimens show cyclic hardening to saturation.(2)Dislocations were very uniformly distributed in specimens with Al_3Sc particle of 11nm in diameter. At higher strain amplitudes, the slip bands were observed in specimens with Al_3Sc particles of 4nm in diameter.(3)The fatigue softening of specimens with 4 nm Al_3Sc particles is unambiguously related to the dissolution of the Al_3Sc particles within the slip bands. Less

已经检查了在573 K或623 K时在退火过程中相等的河道角压力产生的超细粒状Al-3Wt％mg-0.2wt％MG-0.2WT％SC合金的微观结构演变。在短时间内在623 K处退火导致超细晶粒的完全重合。 573K处的结构发展可以分为三个阶段，如下所示：（1）初始阶段（〜30分钟）。硬度随着退火时间而迅速降低，晶粒尺寸从300 nm增加到600 nm。脱位，密度通过恢复，晶粒生长和脱位密度降低而变得较低。（2）中间阶段（30分钟至11小时）。硬度增加，晶粒尺寸几乎保持不变。细珍贵的Al_3Sc颗粒在谷物内部形成。这些颗粒会导致硬度增加。晶界的小al_3sc颗粒固定晶粒边界并限制其迁移。（3）后期（11H〜）。在此阶段，……更多的谷物生长发生，硬度降低。这是因为夹紧力和颗粒增强随着AL_3SC粒径的增加而逐渐减小。从晶粒尺寸和Al_3SC粒子半径之间的线性关系来看，得出的结论是，晶粒的生长受Al3SC颗粒的变色速率控制。塑料控制的低周期疲劳测试的Al-MG-SC合金含有AL_3SC合金，其中含有AL_3SC含量为4 nm和11 nm的平均直径4 nm和11 nm。结果和结论总结如下：（1）直径为4 nm的Al_3SC颗粒的样品显示在较高的塑料固定放大器（ε_<pl> [大于或等于] 1×10^<-3>）下的环状软化。所有其他标本均表现出循环硬化至满意度。（2）脱位非常均匀地分布在直径为11nm的Al_3SC粒子的样品中。在较高的应变幅度下，在直径为4nm的Al_3SC颗粒的样品中观察到滑动带。（3）用4NM AL_3SC颗粒对样品的疲劳软化与滑移带中的Al_3Sc颗粒的溶解明确相关。较少的