Wear Behavior of the Multiheterostructured AZ91 Mg Alloy Prepared by ECAP and Aging.

Bingqian Xu,Jing Han,Zhenquan Yang,Aibin Ma,Jinghua Jiang,Dan Song,Jiapeng Sun

doi:10.1155/2020/4873286

Bingqian Xu, Jing Han + Show 5 more

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https://doi.org/10.1155/2020/4873286

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Abstract

The microstructure design based on the development of heterostructure provides a new way for high strength and ductility Mg alloys. However, the wear property, as an important service performance, of Mg alloys with heterostructure is scarcely investigated. In this work, a high strength and ductility AZ91 Mg alloy with multiheterostructure was prepared via a processing route combined industrial-scale equal channel angular pressing (ECAP) and aging. The multiheterostructure consists of the heterogeneous grain structure and heterogeneous precipitates. The dry sliding wear behavior of this multiheterostructured (MH) alloy is investigated compared to the as-cast alloy. The impacts of the applied load and duration time on the wear volume and coefficient of friction (COF) are analyzed, and the wear mechanism is further discussed. The result indicates that although the MH alloy exhibits high-desirable strength-ductility synergy, it shows a poorer wear resistance but a relatively lower COF compared to the as-cast alloy at the present condition. The wear mechanism of both alloys mainly involves abrasive wear, as well as mild adhesion, delamination, and oxidation. In comparison, the MH alloy shows relatively severe adhesion, delamination, and oxidation. The poor wear resistance of the MH alloy at the present dry sliding wear condition is linked to the abundant grain boundaries and fine precipitates. Therefore, one should reasonably use the MH Mg alloy considering the service conditions to seek advantages and avoid disadvantages.

Highlights

According to the need for lightweight of the structural materials, magnesium (Mg) alloys, as the lightest structural metallic materials, are widely applied in the automobile, aerospace, biomedicine application, and electronics industries [1,2,3,4,5]
This alloy is featured with a typical dendritic structure which consists of a coarse α-Mg matrix with an average grain size of 180 μm, γ-phase precipitates (Mg17Al12), and interdendritic eutectic phase
Some cobblestone-like γphase particles can be found on the grain boundaries, which are dynamically precipitated during equal channel angular pressing (ECAP) processing

Summary

Introduction

According to the need for lightweight of the structural materials, magnesium (Mg) alloys, as the lightest structural metallic materials, are widely applied in the automobile, aerospace, biomedicine application, and electronics industries [1,2,3,4,5]. The absolute strength and ductility of Mg alloys at room temperature are still much lower than that of Al alloys, Ti alloys, and steels, which restrict their widespread commercial applications. Due to the well-known Hall-Petch law, the ultrafine/nanograined Mg alloys are intensely pursued to address the issues of poor strength and ductility [14,15,16,17,18,19]. The microstructure design based on the development of the heterostructure provides a new way for the high-performance materials [20,21,22,23]. Many studies indicate that the heterostructure brings into much higher strength and ductility in several Mg alloys than the generally developed ultrafine grain structure [24, 25]. %) alloy with finegrained bimodal microstructures via multiaxial forging.

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