The effect of size and distribution of rod-shaped β′1 precipitates on the strength and ductility of a Mg-Zn alloy
The effect of size and distribution of rod-shaped β′1 precipitates on the strength and ductility of a Mg-Zn alloy
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DOI：
10.1016/j.msea.2012.01.087
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发表时间：
2012-03-30
期刊：
影响因子：
6.4
通讯作者：
Mukai, Toshiji
中科院分区：
文献类型：
--
作者：
Rosalie, Julian M.;Somekawa, Hidetoshi;Mukai, Toshiji
我们报告了对棒状 13 的尺寸和分布的影响的定量研究；析出物对 Mg-Zn 合金强度和延展性的影响尽管沉淀强化对于镁合金的实际应用至关重要，但这项研究首次系统地研究了受控变形对沉淀物尺寸分布以及由此产生的镁合金强度和延展性的影响。利用预时效变形，通过异质形核获得不同分布的棒状β'(1)析出物。对合金进行挤压以获得织构，以避免形成孪晶，从而确保位错是主要成核位点。预时效应变细化了沉淀物的长度和直径，平均长度从440 nm减小到60 nm，直径从14 nm减小到9 nm。通过显微照片测量颗粒间间距，表明沉淀物分布存在一定的不均匀性。合金的屈服应力从273 MPa增加到309 MPa。屈服应力随着颗粒间间距的倒数而线性增加，但增长率低于 Orowan 强化的预测值。预时效变形还导致延展性显着损失（伸长率从 17% 降至 6%）。失效时的真实应变和均匀伸长率均与颗粒间距呈线性关系，与非变形障碍物周围位错累积的模型一致。与未变形材料相比，经过 3% 预时效变形的样品显示出显着增加的老化响应；然而，额外的变形（至 5% 应变）仅导致析出物分布和机械性能发生适度变化。 (C) 2012 Elsevier B.V. 保留所有权利。
We report on a quantitative investigation into the effect of size and distribution of rod-shaped 13; precipitates on strength and ductility of a Mg-Zn alloy. Despite precipitation strengthening being crucial for the practical application of magnesium alloys this study represents the first systematic examination of the effect of controlled deformation on the precipitate size distribution and the resulting strength and ductility of a magnesium alloy. Pre-ageing deformation was used to obtain various distributions of rod-shaped beta'(1) precipitates through heterogeneous nucleation. Alloys were extruded to obtain a texture so as to avoid formation of twins and thus to ensure that dislocations were the primary nucleation site. Pre-ageing strain refined precipitate length and diameter, with average length reduced from 440 nm to 60 nm and diameter from 14 nm to 9 nm. Interparticle spacings were measured from micrographs and indicated some inhomogeneity in the precipitate distribution. The yield stress of the alloy increased from 273 MPa to 309 MPa. The yield stress increased linearly as a function of reciprocal interparticle spacing, but at a lower rate than predicted for Orowan strengthening. Pre-ageing deformation also resulted in a significant loss of ductility (from 17% to 6% elongation). Both true strain at failure and uniform elongation showed a linear relationship with particle spacing, in agreement with models for the accumulation of dislocations around non-deforming obstacles. Samples subjected to 3% pre-ageing deformation showed a substantially increased ageing response compared to non-deformed material; however, additional deformation (to 5% strain) resulted in only modest changes in precipitate distribution and mechanical properties. (C) 2012 Elsevier B.V. All rights reserved.