Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8002070 | Journal of Alloys and Compounds | 2014 | 7 Pages |
Abstract
Age hardening at 160 °C was performed in an Al-6.0 wt.%Zn-2.3 wt.%Mgâ1.8 wt.%Cuâ0.1 wt.%Zr alloy. It was found that metastable ηⲠphases played a very important role in controlling this behaviour. The alloy reached the 193 HV peak hardness aged for 6 h. Transmission electron microscopy was used to characterise the morphology of ηⲠphases as main strengthening precipitates, and then the high-resolution transmission electron microscopy, combining with Transition Matrix calculation, was used to analysis the orientations and electron diffraction patterns of ηⲠprecipitates. It was found that the ηⲠphases in four variants had only three different zone axis: [24¯23]ηâ², [101¯0]ηⲠand [2¯42¯3]ηâ², parallel to the [1 1 0]Al direction of Al matrix when they were precipitated. By integrating the atomic coordinates, structure factors and double diffraction effect, a new diffraction patterns model under the [1 1 0]Al zone axis was established, which was good in agreement with the experimental result. Simultaneously, Moiré fringes analytical technique was also used to quantitatively verify the lattice parameters and orientation variants of ηⲠprecipitates, and demonstrated that Moiré fringes with about 0.7 nm spacing were the results of the interaction between the 0004ηâ²/0004¯ηⲠdiffraction of ηⲠprecipitates in variants 3/4 under the [101¯0]ηⲠzone axis and the 11¯1Al/11¯1¯Al of Al matrix under the [1 1 0]Al zone axis. Furthermore, the high-resolution transmission electron microscopy image simulation for Moiré fringes of ηⲠprecipitates in the Al matrix presented a good match with the experimental result.
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Physical Sciences and Engineering
Materials Science
Metals and Alloys
Authors
Wenchao Yang, Shouxun Ji, Mingpu Wang, Zhou Li,