Effect of Solution Pretreatment on Homogeneity and Corrosion Resistance of Biomedical Mg–Zn–Ca Alloy Processed by High Pressure Torsion

Abstract

Orthopedic Mg-Zn-Ca alloy is prepared by solution pretreatment and then processed by high pressure torsion (HPT). The results show that the second phases in solution treated (ST) alloy processed by HPT disperse uniformly. While the second phases in HPT-treated cast alloy without solution pretreatment are not completely fragmented and distributed non-uniformly. After five revolutions, the grain refinement is completed. The microhardness of the alloys is significantly improved after HPT, and the microhardness distribution is homogeneous in HPT-treated ST alloy. The corrosion resistance of HPTtreated ST alloy is more excellent than that of HPT-treated cast alloy in physiological environment.

The Effect of High‐Pressure Torsion on Microstructure, Hardness and Corrosion Behavior for Pure Magnesium and Different Magnesium Alloys

“…There are many reports of significant improvements in the corrosion resistance of magnesium alloys due to HPT processing but these reports of corrosion behavior are generally for magnesium alloys in solutions that simulate biological environments . The present results show no clear improvement in the corrosion resistance in a 3.5 wt% NaCl solution for magnesium alloys processed previously by extrusion or through a solution treatment.…”

Processing Magnesium and Its Alloys by High‐Pressure Torsion: An Overview

“…A transition from pitting to homogeneous corrosion was reported in a Mg‐2% Zn‐0.24% Ca alloy and this change in behavior was attributed to homogenization in the precipitate distributions during HPT . The degradation rate was evaluated in a similar alloy using hydrogen evolution tests and the results are shown in Figure for an alloy tested in a simulated body fluid . Thus, a decrease in the degradation rate with increasing numbers of HPT turns is observed in the material processed from the as‐cast condition or after a solution treatment (ST).…”

“…Corrosion rate in Mg–Zn–Ca alloy processed by different number of turns of HPT in simulated body fluid. Reproduced with permission . Copyright 2016, John Wiley and Sons.…”

Electrochemical behavior of a magnesium ZK60 alloy processed by high-pressure torsion

“…However, high-pressure torsion (HPT) is an SPD process that has an established capability in producing significant grain refinement in a range of Mg alloys and, more important, the processing can be effectively conducted at room temperature without the development of segmentation or cracking in the base metal [17,18]. Although the effect of various SPD processes on corrosion of magnesium was investigated thoroughly [5,6,8,12,[19][20][21], nevertheless little attention was devoted to the development of electrochemical behavior in the HPT-processed Mg alloys [9,10,[22][23][24] where reports have centered mainly on noting that more refined grains lead to a more homogenous corrosion. In practice, processing by HPT permits a study of corrosion behavior over a wide range of grain sizes and grain size distributions [25,26].…”