Precipitation Behavior in an Al-Mg Alloy with High Mg Composition

Takuya Yako¹, Koichiro Fukui¹, Mao Naito¹ and Mahoto Takeda^1,

¹Department of Materials Engineering, Yokohama National University, Yokohama 240-8501, Japan

Cite this paper:
Takuya Yako, Koichiro Fukui, Mao Naito and Mahoto Takeda. Precipitation Behavior in an Al-Mg Alloy with High Mg Composition. Materials Science and Metallurgy Engineering. 2018; 5(1):1-4. doi: 10.12691/msme-5-1-1

Abstract

We have investigated the precipitation phenomena which occur at high aging temperatures in an Al-Mg alloy with high Mg concentration by means of Vickers hardness (HV) testing, differential scanning calorimetry (DSC), transmission electron microscopy (TEM) and analytical scanning transmission electron microscopy (STEM-EDX). It was found that the hardness and heat changes are closely correlated, and that the size of the exothermic heat peak depends on the quantity of β'- phase formed during isothermal aging prior to the DSC measurements. This implies that the formation of β'-phase precipitates is mainly responsible for the increase in hardness. Our TEM observations showed that β'-phase precipitates are plate-like in morphology and form on matrix {100}planes, whilst stable β-phase precipitates are granular in shape. In-situ TEM using a heating holder revealed that β-phase precipitates grew by consumption of β'-phase platelets. Element-maps obtained by STEM-EDX indicated that the composition of β'-phase platelets was approximately Al-33at%Mg.

Keywords:
aluminum-magnesium alloy precipitation isothermal aging Vickers microhardness differential scanning calorimetry transmission electron microscopy

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