期刊
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
卷 91, 期 -, 页码 78-89出版社
JOURNAL MATER SCI TECHNOL
DOI: 10.1016/j.jmst.2021.01.096
关键词
Aluminum-lanthanum-cerium alloys; Nanostructured alloys; Reverse Hall-Petch relationship; Precipitation hardening; Dislocation hardening
资金
- Light Metals Educational Foundation of Japan
- Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan [19H05176, 21H00150]
- Russian Science Foundation [17-19-01311]
The study achieved nanograin sizes in an Al-La-Ce alloy through ultra-SPD followed by aging, and identified two breaks in the Hall-Petch relationship. Detailed analysis confirmed that nanograin formation alone is not sufficient for extra hardening, and additional strategies such as grain-boundary segregation and precipitation are necessary to address the issue of softening.
To have an insight into the occurrence of inverse Hall-Petch relationship in ultrafine-grained (UFG) aluminum alloys produced by severe plastic deformation (SPD), ultra-SPD (i.e. inducing several ten thousand shear strains via high-pressure torsion, HPT) followed by aging is applied to an Al-La-Ce alloy. Average nanograin sizes of 40 and 80 nm are successfully achieved together with strain-induced Lomer-Cottrell dislocation lock formation and aging-induced semi-coherent Al-11(La,Ce)(3) precipitation. Analysis of hardening mechanisms in this alloy compared to SPD-processed pure aluminum with micrometer grain sizes, SPD-processed Al-based alloys with submicrometer grain sizes and ultra-SPD-processed Al-Ca alloy with nanograin sizes reveals the presence of two breaks in the Hall-Petch relationship. First, a positive up-break appears when the grain sizes decrease from micrometer to submicrometer which is due to extra hardening by solute-dislocation interactions. Second, a negative down-break and softening occur by decreasing the grain sizes from submicrometer to nanometer which is caused by weakening the dislocation hardening mechanism with minor contribution of the inverse Hall-Petch mechanism. Detailed analyses confirm that nanograin formation is not necessarily a solution for extra hardening of Al-based alloys and other accompanying strategies such as grain-boundary segregation and precipitation are required to overcome such a down-break and softening. (C) 2021 Published by Elsevier Ltd on behalf of Chinese Society for Metals.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据