Precipitation induced room temperature superplasticity in Zn-Cu alloys

Mostaed, Ehsan; Ardakani, Morteza S.; Sikora-Jasinska, Malgorzata Urszula; Drelich, Jaroslaw

doi:10.1016/j.matlet.2019.02.084

Cited by 48 publications

(35 citation statements)

References 9 publications

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“…Interestingly, UTS achieved higher values after HT-3 and HT-5, which suggests that strain-softening was suppressed to some extent, but applied HT-15 caused the decrease in flow stresses. Nevertheless, a similar observation was reported for the Zn–1Cu alloy, where the gradual precipitates' dissolution and grain growth during short-time annealing resulted in the decrease in UTS during tensile tests [ 44 ].…”

Section: Discussionsupporting

confidence: 72%

“…Moreover, the observed decrease in strength compared to the HE state can be related to precipitation-induced softening. It has already been presented for the Zn–1Cu alloy that extensive cold deformation processing can contribute to the precipitation of fine secondary phases from non-equilibrium η-Zn(Cu) solid solution [ 44 ]. A similar situation may occur in the examined CR Zn–3Ag-0.5Mg alloy since the matrix is composed of η-Zn(Ag) solid solution, and similar precipitations of the ε-Zn 3 Ag intermetallic phase may occur.…”

Section: Discussionmentioning

confidence: 99%

“…This effect seems to be more pronounced in samples deformed with higher CR reductions. A high fraction of deformation-induced secondary precipitates could affect the observed mechanical properties by activating phase boundary sliding (PBS) at the matrix-precipitate interphase boundaries instead of dislocation – precipitate interaction [ 15 , 44 ].…”

Section: Discussionmentioning

confidence: 99%

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Fine-tuning of mechanical properties in a Zn–Ag–Mg alloy via cold plastic deformation process and post-deformation annealing

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et al. 2021

Bioactive Materials

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In recent years, Zn-based materials have been extensively investigated as potential candidates for biodegradable implant applications. The introduction of alloying elements providing solid-solution strengthening and second phase strengthening seems crucial to provide a suitable platform for the thermo-mechanical strengthening of Zn alloys. In this study, a systematic investigation of the microstructure, crystallographic texture, phase composition, and mechanical properties of a Zn–3Ag-0.5Mg (wt%) alloy processed through combined hot extrusion (HE) and cold rolling (CR), followed by short-time heat treatment (CR + HT) at 200 °C was conducted. Besides, the influence of different annealing temperatures on the microstructure and mechanical properties was studied. An adequate combination of processing conditions during CR and HT successfully addressed brittleness obtained in the high-strength HE Zn–3Ag-0.5Mg alloy. By controlling the microstructure, the most promising results were obtained in the sample subjected to 50% CR reduction and 5-min annealing, which were: ultimate tensile strength of 432 MPa, yield strength of 385 MPa, total elongation to failure of 34%, and Vickers microhardness of 125 HV0.3. The obtained properties clearly exceed the mechanical benchmarks for biodegradable implant materials. Based on the conducted investigation, brittle multi-phase Zn alloys' mechanical performance can be substantially enhanced to provide sufficient plasticity by grain refinement through cold deformation process, followed by short-time annealing to restore proper strength.

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Section: Discussionsupporting

confidence: 72%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Fine-tuning of mechanical properties in a Zn–Ag–Mg alloy via cold plastic deformation process and post-deformation annealing

Wątroba

Bednarczyk

Kawałko

et al. 2021

Bioactive Materials

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“…The phenomenon of room temperature dynamic precipitation was recently discovered by our group in the Zn-Cu alloy system [38]. In the case of the AM46 wire, as shown in Fig.…”

Section: Microstructural and Mechanical Characterizations Of The Wiresmentioning

confidence: 77%

“…As such, suppression of the strain softening is an essential consideration for stent materials. Moreover, Zn is highly strain rate sensitive even at room temperature [38,39]. Therefore, a stent made of Zn, which is under cyclic loading, may collapse due to creep-fatigue interaction regardless of the stress magnitude [13].…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2020

Self Cite

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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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A Novel High-Strength Zn-3Ag-0.5Mg Alloy Processed by Hot Extrusion, Cold Rolling, or High-Pressure Torsion

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Kawałko

et al. 2020

Metall Mater Trans A

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A novel Zn-3Ag-0.5Mg alloy was plastically deformed using 3 processing paths: hot extrusion (HE), HE followed by cold rolling (CR) and high-pressure torsion (HPT). The processed samples consisted of the η-Zn phase, ε-Zn3Ag precipitates within the matrix, and nanometric Zn2Mg precipitates within the Zn11Mg2 phase located at the grain boundaries. Both the η-Zn phase and Mg-rich phases were enriched in Ag. Electron backscattered diffraction was used to examine the effects of grain size and texture on mechanical behavior with tensile tests performed at room temperature (RT) at different strain rates. The coarse-grained (~ 6 µm) samples after HE exhibited high strength with brittleness due to dislocation interaction with dispersed precipitates and, to some extent, with twinning activation. Significant grain refinement and processing at RT gave an increase in elongation to over 50 pct in CR and 120 pct in HPT. Ductile CR samples with an average grain size of ~ 2 µm and favorable rolling deformation texture gave a yield strength of ~ 254 MPa, a tensile strength of ~ 456 MPa, and a reasonable strain rate sensitivity. These values for the CR samples meet the mechanical requirements for biodegradable stents in cardiovascular applications.

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Precipitation induced room temperature superplasticity in Zn-Cu alloys

Cited by 48 publications

References 9 publications

Fine-tuning of mechanical properties in a Zn–Ag–Mg alloy via cold plastic deformation process and post-deformation annealing

Fine-tuning of mechanical properties in a Zn–Ag–Mg alloy via cold plastic deformation process and post-deformation annealing

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

A Novel High-Strength Zn-3Ag-0.5Mg Alloy Processed by Hot Extrusion, Cold Rolling, or High-Pressure Torsion

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