Early-stage clustering and precipitation behavior in the age-hardened Al-Mg-Zn(-Cu) alloys
Early-stage clustering and precipitation behavior in the age-hardened Al-Mg-Zn(-Cu) alloys
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DOI：
10.1016/j.msea.2022.144015
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发表时间：
2022-09-24
期刊：
影响因子：
6.4
通讯作者：
Zhuang, Linzhong
中科院分区：
文献类型：
--
作者：
Geng, Yingxin;Zhang, Di;Zhuang, Linzhong
T-Mg-32（AlZnCu）（49）相强化的Al-Mg-Zn-Cu合金具有良好的时效硬化性能。然而，在早期沉淀期间，不同热处理的时效硬化机制尚不清楚。此外，缺乏早期沉淀的信息阻碍了该系列合金的发展。本研究利用透射电子显微镜和原子探针层析分析技术研究了新型Al-Mg-Zn（-Cu）合金在析出初期的Guinier-Preston（GP）区和T '相的形成。研究表明，Cu含量和热处理对合金的组织演变有显著影响。GP区被观察到作为网站的T '相的形成。较高的数密度的Cu掺入GP区导致较高的强度和烘烤硬化后的响应预老化。偶尔，观察到一些GPI区溶解到Al基体中，而没有进一步转化为T′沉淀物在自然时效（NA）。在NA之前的预老化促进了稳定的GP区的形成并减轻了NA的负面影响。此外，在180 ℃的单步时效后，析出物生长到可感知的尺寸，这对新型合金的机械性能产生不利影响。研究结果为交叉Al-Mg-Zn-（Cu）合金中T相的设计提供了有效的指导。
T-Mg-32(AlZnCu)(49) phase-strengthened Al-Mg-Zn-Cu alloys have shown a promising age-hardening response. However, the age-hardening mechanism underlying the different heat treatments is not clear during the early-stage precipitation. Additionally, the lack of information on the early-stage precipitation impedes the development of this series alloys. In this study, the formation of the Guinier-Preston (GP) zone and T'-phase of the novel Al-Mg-Zn(-Cu) alloys during the early-stage precipitation has been investigated using transmission electron microscopy and atom probe tomography analysis. Investigation revealed that the Cu content and thermal treatment had significant effects on the microstructure evolution of the alloys. GP zones were observed to act as sites for the formation of the T'-phase. The higher number density of Cu-incorporated GP zones led to higher strength and bake-hardening response after pre-aging. Occasionally, some GPI zones were observed to dissolve into the Al matrix without further transforming into T & PRIME; precipitates during natural aging (NA). Pre-aging prior to NA facilitated stable GP zone formation and mitigated the negative effect of NA. Furthermore, the precipitates were grown to an appreciable size after single-step aging at 180 C, which adversely affected the mechanical properties of the novel alloys. The present findings provide an efficient guideline for designing the T-phase in the crossover Al-Mg-Zn-(Cu) alloys.