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11 pages, 5802 KiB

Open AccessArticle

Microstructure and Mechanical Properties in a Gd-Modified Extruded Mg-4Al-3.5Ca Alloy

by Jixue Zhou, Dongqing Zhao, Shouqiu Tang, Yu Liu, Suqing Zhang, Yunteng Liu, Jianhua Wu, Xiaocun Song, Hongtao Liu, Xinfang Zhang, Pengfei Yan and Xitao Wang

Metals 2023, 13(8), 1333; https://doi.org/10.3390/met13081333 - 26 Jul 2023

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Abstract

In the present study, the microstructure and mechanical properties of a new Mg-4Al-3.5Ca-2Gd (AXE432) alloy are investigated. The microstructure of the as-cast AXE432 alloy consists of α-Mg, C14 (Mg₂Ca), and C36((Mg, Al)₂Ca) phases. After the heat treatment at 480 [...] Read more.

In the present study, the microstructure and mechanical properties of a new Mg-4Al-3.5Ca-2Gd (AXE432) alloy are investigated. The microstructure of the as-cast AXE432 alloy consists of α-Mg, C14 (Mg₂Ca), and C36((Mg, Al)₂Ca) phases. After the heat treatment at 480 °C for 8 h, the C14 with fine lamellar structure changes from narrow stripes to micro-scale particles, and part of the C36 and the C14 dissolve into the α-Mg matrix, with many short needle-shaped C15 (Al₂Ca) phase precipitating in the primary a-Mg grains. The AXE432 alloy extruded at a temperature as high as 420 °C exhibits a refined dynamically recrystallized (DRXed) microstructure with grain sizes less than 1.5 ± 0.5 μm and a strong {0001}<10

\bar{1}

0> basal texture with a maximum intensity of 5.62. A complex combination of the effects from grain size, texture, second-phase particles, and strain hardening results in balanced mechanical properties, with the tensile yield strength (TYS), ultimate tensile strength (UTS), elongation (El), compressive yield strength (CYS), and ultimate compressive strength (UCS) of 331.4 ± 2.1 MPa, 336.9 ± 3.8 MPa, 16.1 ± 2.3%, 270.4 ± 1.6 MPa and 574.5 ± 12.4 MPa, respectively. Full article

(This article belongs to the Special Issue Advance of Carbon Reinforced Metal-Matrix Composites)

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7 pages, 15480 KiB

Open AccessCommunication

Investigation of Copper–Carbon Composite Microstructure and Properties

by Elizaveta Bobrynina, Tatiana Koltsova and Tatiana Larionova

Metals 2023, 13(6), 1052; https://doi.org/10.3390/met13061052 - 31 May 2023

Cited by 3 | Viewed by 1055

Abstract

This paper presents a study of microstructures and properties of pure copper and copper–fullerene-soot (Cu-FS) composite materials produced by mechanical milling followed by hot pressing. The electrochemical etching method was successfully applied to reveal the fragmented structure of the specimens produced by high-energy [...] Read more.

This paper presents a study of microstructures and properties of pure copper and copper–fullerene-soot (Cu-FS) composite materials produced by mechanical milling followed by hot pressing. The electrochemical etching method was successfully applied to reveal the fragmented structure of the specimens produced by high-energy ball milling. It is shown the carbon nanoparticles are involved in the composite microstructure formation. Copper–fullerene-soot composite materials have a complex microstructure with a bimodal grain distribution. Both recrystallized (average 3 μm) and polygonized (155 nm) grains are observed in the microstructure. Thus, in the case of pure copper, due to the absence of carbon nanoparticles, only recrystallized grains are observed in the microstructure. The Cu-FS composite has a hardness up to 160 HV and thermal stability up to 700 °C. Full article

(This article belongs to the Special Issue Advance of Carbon Reinforced Metal-Matrix Composites)

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13 pages, 14900 KiB

Open AccessArticle

Effects of Mold Temperature on the Microstructures and Tensile Properties of the Thixoforged Graphite/AZ91D Composite

by Kejian Geng, Haipeng Jiang, Suqing Zhang, Xin Gao, Jianhua Wu, Cuicui Sun, Jixue Zhou and Xinfang Zhang

Metals 2023, 13(5), 1000; https://doi.org/10.3390/met13051000 - 21 May 2023

Cited by 1 | Viewed by 1117

Abstract

The effects of mold temperatures on the microstructures and mechanical properties of thixoforged Grp (graphite particles)/AZ91D composites have been investigated, followed by partial remelting and thixoforging technology. The results indicate that the best semi-solid microstructure could be obtained after being partially remelted at [...] Read more.

The effects of mold temperatures on the microstructures and mechanical properties of thixoforged Grp (graphite particles)/AZ91D composites have been investigated, followed by partial remelting and thixoforging technology. The results indicate that the best semi-solid microstructure could be obtained after being partially remelted at 600 °C and held for 60 min. Correspondingly, under a mold temperature of 300 °C, the best tensile properties were obtained by thixoforging. The UTS (ultimate tensile strength) and elongation of the thixoforged Grp/AZ91D were up to 304.1 MPa and 13.9%, respectively, which increased 11.3% and 43.1% in comparison with the thixoforged AZ91D, respectively. The variation of the tensile properties responded to the influences of mold temperatures on the amount of eutectic phase, the distribution of Grp, and the grain size of α-Mg. Meanwhile, HRTEM (High Resolution Transmission Electron Microscope) showed good bonding between Grp and AZ91D, and many edge dislocations were found in the inverse FFT (Fast Fourier Transform) image. And the result showed that the increase in tensile properties is attributed to the synergistic effect of load transfer, dislocation strengthening, and Orowan looping mechanisms from the Grp strengthening the matrix. Full article

(This article belongs to the Special Issue Advance of Carbon Reinforced Metal-Matrix Composites)

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