Grain size and texture dependence on mechanical properties, asymmetric behavior and low temperature superplasticity of ZK60 Mg alloy

Fabrizi, Alberto; Dellasega, David; Bonollo, Franco; Vedani, Maurizio

doi:10.1016/j.matchar.2015.06.009

Cited by 49 publications

(17 citation statements)

References 28 publications

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“…However, the m value and fracture elongation significantly decrease at higher strain rates (region III), suggesting that the ratecontrolling deformation process is dislocation slip [54]. It is well documented that grain refinement in metals enhances the superplastic ductility [55,56]. Superplasticity is a diffusion-controlled process requiring temperatures above 0.5Tm and grain size smaller than 10 μm [57].…”

Section: Microstructural and Mechanical Characterizations Of The Wiresmentioning

confidence: 97%

Towards revealing key factors in mechanical instability of bioabsorbable Zn-based alloys for intended vascular stenting

et al. 2020

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Zn-based alloys are recognized as promising bioabsorbable materials for cardiovascular stents, due to their biocompatibility and favorable degradability as compared to Mg. However, both low strength and intrinsic mechanical instability arising from a strong strain rate sensitivity and strain softening behavior make development of Zn alloys challenging for stent applications. In this study, we developed binary Zn-4.0Ag and ternary Zn-4.0Ag-xMn (where x= 0.2-0.6wt%) alloys. An experimental methodology was designed by cold working followed by a thermal treatment on extruded alloys, through which the effects of the grain size and precipitates could be thoroughly investigated. Microstructural observations revealed a significant grain refinement during wire drawing, leading to an ultrafine-grained (UFG) structure with a size of 700 nm and 200 nm for the Zn-4.0Ag and Zn-4.0Ag-0.6Mn, respectively. Mn showed a powerful grain refining effect, as it promoted the dynamic recrystallization. Furthermore, cold working resulted in dynamic precipitation of AgZn3 particles, distributing throughout the Zn matrix. Such precipitates triggered mechanical degradation through an activation of Zn/AgZn3 boundary sliding, reducing the tensile strength by 74% and 57% for Zn-4.0Ag and Zn-4.0Ag-0.6Mn, respectively. The observed precipitation softening caused a strong strain rate sensitivity in cold drawn alloys. Short-time annealing significantly mitigated the mechanical instability by reducing the AgZn3 fraction. The ternary alloy wire showed superior microstructural stability relative to its Mn-free counterpart due to the pinning effect of Mn-rich particles on the grain boundaries. Eventually, a shift of the corrosion regime from localized to more uniform was observed after the heat treatment, mainly due to the dissolution of AgZn3 precipitates.

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Section: Microstructural and Mechanical Characterizations Of The Wiresmentioning

confidence: 97%

Towards revealing key factors in mechanical instability of bioabsorbable Zn-based alloys for intended vascular stenting

et al. 2020

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“…As is well-documented in the literature [115,116], hexagonal close packed (hcp) metals and related alloys with c/a (where c is the elementary cell extension along hexagonal axis and a is the dimension along the hexagons) ratios close to the ideal value of 1.633 tend to form basal fiber textures during extrusion due to the high activity of basal slip systems. Fig.…”

Section: Discussion and Comparative Summerymentioning

confidence: 99%

“…EBSD maps and the corresponding inverse pole figures of (a) ZK60 and (b) Zn-0.5Mg alloys. Reprinted with permission [43,116]. …”

Section: Figmentioning

confidence: 99%

Zinc-based alloys for degradable vascular stent applications

et al. 2018

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Numerous studies on magnesium and iron materials have been reported to date, in an effort to formulate bioabsorbable stents with tailorable mechanical characteristics and corrosion behavior. Crucial concerns regarding poor ductility and remarkably rapid corrosion of magnesium, and very slow degradation of iron, seem to be still not desirably fulfilled. Zinc was introduced as a potential implant material in 2013 due to its promising biodegradability and biocompatibility. Since then, extensive investigations have been made toward development of zinc alloys that meet clinical benchmarks for vascular scaffolding. This review critically surveys the zinc alloys developed since 2013 from metallurgical and biodegradation points of view. Microstructural features, mechanical, corrosion and in vivo performances of these new alloys are thoroughly reviewed and evaluated.

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“…Although ECAP can refine grains, the high strength and toughness may not be necessarily achieved. The yield strength of Mg alloys may be reduced after ECAP, especially those with strong basal textures [17,[25][26][27][28][29]. How to ensure the reasonable match between microstructure refinement and texture modification during ECAP is the critical point to improve strength and toughness.…”

Section: Introductionmentioning

confidence: 99%

Influence of Texture on the Mechanical Properties of a Mg-6Al-1Zn-0.9Sn Alloy Processed by ECAP

Hong¹,

Guo²,

Zhang³

et al. 2021

Materials

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The microstructure and mechanical properties of a Mg-6Al-1Zn-0.9Sn alloy processed by equal channel angular pressing (ECAP) at temperatures of 250 °C and 300 °C were investigated. It was found that the refinement of the microstructure was very dependent on the processing temperature. The main reason for the difference in grain refinement was the precipitation of secondary-phase particles. Texture information obtained by electron back-scatter diffraction (EBSD) showed the gradual formation of a 45° texture during the ECAP process, while the maximum intensity was different for processing temperatures at 250 °C and 300 °C. By calculating the contribution from different strengthening mechanisms, it was found that a 45° texture had a huge influence on grain boundary strengthening and thus the yield strength.

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Grain size and texture dependence on mechanical properties, asymmetric behavior and low temperature superplasticity of ZK60 Mg alloy

Cited by 49 publications

References 28 publications

Towards revealing key factors in mechanical instability of bioabsorbable Zn-based alloys for intended vascular stenting

Towards revealing key factors in mechanical instability of bioabsorbable Zn-based alloys for intended vascular stenting

Zinc-based alloys for degradable vascular stent applications

Influence of Texture on the Mechanical Properties of a Mg-6Al-1Zn-0.9Sn Alloy Processed by ECAP

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