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Zinc (Zn) alloys, particularly those incorporating magnesium (Mg), have been explored as potential bioabsorbable metals. However, there is a continued need to enhance the corrosion characteristics of Zn-Mg alloys to fulfill the requirements for biodegradable implants. This work involves a corrosion behavior comparison between severe-plastic-deformation (SPD) processed cast Zn-Mg alloys and their hybrid counterparts, having equivalent nominal compositions. The SPD processing technique used was high-pressure torsion (HPT), and the corrosion behavior was studied as a function of the number of turns (1, 5, 15) for the Zn-3Mg (wt.%) alloy and hybrid and as a function of composition (Mg contents of 3, 10, 30 wt.%) for the hybrid after 15 turns. The results indicated that HPT led to multimodal grain size distributions of ultrafine Mg-rich grains containing MgZn2 and Mg2Zn11 nanoscale intermetallics in a matrix of coarser dislocation-free Zn-rich grains. A greater number of turns resulted in greater corrosion resistance because of the formation of the intermetallic phases. The HPT hybrid was more corrosion resistant than its alloy counterpart because it tended to form the intermetallics more readily than the alloy due to the inhomogeneous conditions of the materials before the HPT processing as well as the non-equilibrium conditions imposed during the HPT processing. The HPT hybrids with greater Mg contents were less corrosion resistant because the addition of Mg led to less noble behavior.
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Corrosion Behavior and Hardness of Binary Mg Alloys Produced via High-Energy Ball-Milling and Subsequent Spark Plasma Sintering
In this work, nine nanocrystalline binary Mg alloys were synthesized by high-energy ball milling. The compositions, Mg-5 wt% M (M-Cr, Ge, Mn, Mo, Ta, Ti, V, Y, and Zn), were milled with the objective of achieving non-equilibrium alloying. The milled alloys were consolidated via cold compaction (CC) at 25°C and spark plasma sintering (SPS) at 300°C. X-ray diffraction (XRD) analysis indicated grain refinement below 100 nm, and the scanning electron microscopy revealed homogeneous microstructures for all compositions. XRD analysis revealed that most of the alloys showed a change in the lattice parameter, which indicates the formation of a solid solution. A significant increase in the hardness compared to unmilled Mg was observed for all of the alloys. The corrosion behavior was improved in all of the binary alloys compared to milled Mg. A significant decrease in the cathodic kinetics was evident due to Ge and Zn additions. The influence of the alloying elements on corrosion behavior has been categorized and discussed based on the electrochemical response of their respective binary Mg alloys.
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- Award ID(s):
- 1846887
- PAR ID:
- 10219878
- Date Published:
- Journal Name:
- Corrosion
- Volume:
- 77
- Issue:
- 2
- ISSN:
- 0010-9312
- Page Range / eLocation ID:
- 228 to 241
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.5006/3633
