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1

Effect of Cooling Rate on the Microstructure and Mechanical Properties of Al-33 wt.% Cu Alloy

Lee Yeon-Joo, Kwon Do-Hun, Cha Eun-Ji, Song Yong-Wook, Choi Hyun Joo, Kim Hwi-Jun

Archives of Metallurgy and Materials

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2023

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Vol. 68, iss. 1

43--46

EN

Directed energy deposition (DED) is an additive manufacturing process wherein an energy source is focused on a substrate on which a feedstock material is simultaneously delivered, thereby forming a small melt pool. Melting, solidification, and subsequent cooling occur at high rates with considerable thermal gradients compared with traditional metallurgical processes. Hence, it is important to examine the effects of cooling rates on the microstructures and properties of the additive manufactured materials. In this study, after performing DED with various energy densities, we investigated the changes in the microstructures and Vickers hardness of cast Al-33 wt.% Cu alloy, which is widely used to estimate the cooling rate during processing by measuring the lamellar spacing of the microstructure after solidification. The effects of the energy density on the cooling rate and resultant mechanical properties are discussed, which suggests a simple way to estimate the cooling rate indirectly. This study corresponds to the basic stage of the current study, and will continue to apply DED in the future.

2

Fabrication of Aluminum Matrix Composite Reinforced with Al0.5CoCrCuFeNi High-Entropy Alloy Particles

Kim Min Sang, Son Han Sol, Joo Gyeong Seok, Kim Young Do, Choi Hyun Joo, Kim Se Hoon

Archives of Metallurgy and Materials

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2022

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Vol. 67, iss. 4

1543--1546

EN

The aluminum composite with dispersed high entropy alloy were developed by stir casting involving the powder-in-tube method. First, Al0.5CoCrCuFeNi high entropy alloy (HEA) powder was made by mechanical alloying, and the powder was extruded in a tube-type aluminum container to form HEA precursor. The extruded HEA precursor was then dispersed in the aluminum matrix via stir casting. As a result, Fe-Cr-Ni based high-entropy phases was uniformly formed in the aluminum matrix, revealing ~158, 166, 235% enhancement of tensile strength by incorporating 1, 3, and 5 wt% HEA particles, respectively.

3

Effect of Fe-Mn Solid Solution Precursor Addition on Modified AA 7075

Kim Min Sang, Kim Dae Young, Kim Young Do, Choi Hyun Joo, Kim Se Hoon

Archives of Metallurgy and Materials

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2021

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Vol. 66, iss. 3

783--787

EN

This study suggests a new way to modify the size and morphology of Al-Fe phases in modified AA 7075 by using an Fe-Mn solid solution powder as the precursor. When Fe and Mn are added in the form of a solid solution, the diffusion of Fe and Mn toward the Al is delayed, thus altering the chemical composition and morphology of the precipitates. The fine, spherical precipitates are found to provide a good balance between strength and ductility compared to the case where Fe and Mn are separately added.