The Effect of Equal-Channel Angular Pressing on Microstructure, Mechanical Properties, and Biodegradation Behavior of Magnesium Alloyed with Silver and Gadolinium

Abstract

The effect of equal channel angular pressing (ECAP) on the microstructure, texture, mechanical properties, and corrosion resistance of the alloys Mg-6.0%Ag and Mg-10.0%Gd was studied. It was shown that ECAP leads to grain refinement of the alloys down to the average grain size of 2–3 μm and 1–2 μm, respectively. In addition, in both alloys the precipitation of fine particles of phases Mg54Ag17 and Mg5Gd with sizes of ~500–600 and ~400–500 nm and a volume fraction of ~9% and ~8.6%, respectively, was observed. In the case of the alloy Mg-6.0%Ag, despite a significant grain refinement, a drop in the strength characteristics and a nearly twofold increase in ductility (up to ~30%) was found. This behavior is associated with the formation of a sharp inclined basal texture. For alloy Mg-10.0%Gd, both ductility and strength were enhanced, which can be associated with the combined effect of significant grain refinement and an increased probability of prismatic and basal glide. ECAP was also shown to cause a substantial rise of the biodegradation rate of both alloys and an increase in pitting corrosion. The latter effect is attributed to an increase in the dislocation density induced by ECAP and the occurrence of micro-galvanic corrosion at the matrix/particle interfaces.

Improved Mechanical Properties of Biocompatible Zn-1.7%Mg and Zn1.7%Mg-0.2%Zr Alloys Deformed with High-Pressure Torsion

“…A similar texture was formed in the Zn-0.5Cu alloy processed using high-pressure torsion, which also led to a significant increase in ductility [22]. A notable enhancement in ductility is also observed in Mg-based alloys where a basal texture is formed after deformation [42][43][44]. The presence of fine-dispersed (Mg, Zr) 2 Zn 11 particles in the Zn-1.7%Mg-0.2%Zr alloy after HPT can hinder the improvement of ductility during deformation.…”

Реологические Исследования Сплава МА14

“…Одной из важных задач для магния и его сплавов является выбор технологических условий деформационной обработки, т.к. они имеют гексагональную плотноупакованную решетку, в силу особенностей данного типа кристаллической решетки, а именно ограниченного количества плоскостей скольжения, зависящих от условий обработки [10][11][12]. Минимальная температура деформационной обработки магниевых сплавов начинается с 200 °С [9], а максимальная температура достигает 400-450 °C согласно литературным данным [3,4].…”

Effects of Severe Plastic Deformation and Ultrasonic Treatment on the Structure, Strength, and Corrosion Resistance of Mg-Al-Zn Alloy

“…To increase the number of possible slip systems, it is usually required to increase the deformation processing temperature, which has a natural effect on the level of resulting properties. The latest trend is to decrease the deformation processing temperature to achieve the highest final strength [ 6 , 7 , 8 ].…”