Effect of Ag addition on microstructure and mechanical properties of Mg–14Gd–0.5Zr alloy

Li, R.G.; Xin, Renlong; Liu, Q.; Liu, J.A.; Fu, Guang; Zong, Liang; Yu, Yongmei; Guo, Shun

doi:10.1016/j.matchar.2015.09.022

Cited by 36 publications

(5 citation statements)

References 35 publications

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“…[15] Regarding the chemical composition of the Ag-bearing phase and the XRD results (Figure 2(b)) in this study, the newly formed Mg 16 Gd 2 YAg precipitates in the GW63-1Ag alloy could be classified as Mg 5 (Gd,X)-type compounds, which are also known as the ''equilibrium b phase'' in the literature [11,28,29] with a face-centered cubic crystallographic structure and a lattice parameter equal to 2.23 nm. A similar intermetallic phase has been reported elsewhere, [23] where Ag has been incorporated into the Mg-Gd alloys; addition of 2 wt pct Ag into a hot extruded Mg-14Gd-0.5Zr alloy led to the formation of Mg 5 Gd precipitates at the grain boundaries and a subsequent decrease in the grain size from 5 to 2 lm.…”

Section: A Microstructural Observations Of the Extruded Alloyssupporting

confidence: 75%

“…Ag is considered an effective grain refinement agent in the Mg-Gd-Y alloys, which can promote formability and strength at elevated temperatures. Movahedi-Rad and Mahmudi [22] and Li et al [23] reported significant grain size reduction and mechanical property enhancement in the extruded Mg-Gd-Y-Zr alloys by Ag addition. However, there is a lack of data in the literature on the effect of Ag addition on the hot deformation behavior of the Mg-Gd-Y alloys.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Ag Addition on the Hot Deformation, Constitutive Equations and Processing Maps of a Hot Extruded Mg-Gd-Y Alloy

Rezaei

Mahmudi

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2020

Metall Mater Trans A

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Hot deformation behavior of the extruded Mg-6Gd-3Y (GW63) and Mg-6Gd-3Y-1Ag (GW63-1Ag) alloys was assessed by shear punch testing (SPT) method in the temperature range of 623 K to 723 K and shear strain rate of 1.6 9 10 À2 to 1.3 9 10 À1 s À1. Microstructural examinations showed that Ag addition decreased the initial grain size from 10.1 to 2.9 lm. According to the hot deformation results, hyperbolic-sine exponents (n-values) of 3.39 and 2.54 were obtained for the Ag-free and Ag-containing alloys, respectively. The corresponding activation energies were found to be 321 and 178 kJ mol À1 for these alloys. Therefore, the controlling deformation mechanisms were defined as viscous glide of dislocation for the Mg-6Gd-3Y alloy and grain boundary sliding for Mg-6Gd-3Y-1Ag. Processing maps were developed based on the dynamic material model (DMM) to determine the flow instability domains during hot deformation. Accordingly, the optimum hot working conditions were found to be in the temperature range of 655 K to 723 K and shear strain rate of 3.3 9 10 À2 to 1.3 9 10 À1 s À1 for the GW63-1Ag alloy, whereas the safe deformation window for the GW63 alloy was narrowed down to a temperature range of 665 K to 705 K and shear strain rate of 7.2 9 10 À2 to 1.3 9 10 À1 s À1. The Ag-containing alloy exhibited flow instability regions only at low temperatures and high strain rates. On the other hand, the Ag-free alloy demonstrated other instability domains comprising the formation of mechanical twins and cracking. Electron back-scattered diffraction analysis was utilized to correlate the microstructural evolution of the alloys after shear deformation to the hot working parameters. Continuous dynamic recrystallization was suggested as the main mechanism for generation of the dynamically recrystallized grains during hot deformation of both alloys.

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Section: A Microstructural Observations Of the Extruded Alloyssupporting

confidence: 75%

Section: Introductionmentioning

confidence: 99%

Effect of Ag Addition on the Hot Deformation, Constitutive Equations and Processing Maps of a Hot Extruded Mg-Gd-Y Alloy

Rezaei

Mahmudi

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2020

Metall Mater Trans A

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“…Early in 1960s, Payne and Bailey found that the age hardening response of binary Mg-Nd alloys could be significantly improved by Ag addition, which subsequently led to the development of a commercial alloy designated QE22 (Mg-2.5Ag-2Nd-0.7Zr, wt pct) [14]. The addition of Ag to other Mg-RE based alloys, such as Mg-Gd-Zr alloys [17][18][19][20][21] and Mg-Y-Zn-Zr alloys [22][23][24], could also lead to a remarkable increase in age hardening response. QE22 alloy is well known for its good tensile properties at elevated temperature and creep resistance and has been used in the aircraft and aerospace industries [3,4].…”

Section: Introductionmentioning

confidence: 99%

On the Equilibrium Intermetallic Phase in Mg-Nd-Ag Alloys

Zhao

Chen

et al. 2019

Metall Mater Trans A

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The equilibrium intermetallic phase in Mg-Nd-Ag alloys has not been well understood. In this work, intermetallic particles in the solution-treated microstructure of commercial magnesium alloy QE22 (Mg-2.5Ag-2.0Nd-0.7Zr, wt pct) have been investigated using scanning electron microscopy, electron diffraction, atomic-resolution imaging and mapping techniques of scanning transmission electron microscopy (STEM) and thermodynamic modelling. The intermetallic particles are distributed in the inter-dendritic regions. They have coarse irregular shape and share the same crystal structure. The intermetallic phase (designated δ) is determined to have an orthorhombic structure (space group Cmcm, a = 1.02 nm, b = 1.18 nm, c = 1.00 nm) and a composition of NdAgMg11, which are different from those reported previously. An atomic model is proposed for the δ phase based on atomicresolution STEM images and atomic-scale energy-dispersive X-ray spectroscopy maps. The δ lattice is structurally related to that of Mg12Nd phase in binary Mg-Nd alloys. The Gibbs energy of formation of NdAgMg11 is determined from the equilibrium study at 793 K (520 °C), including the entropy of formation using the present experimental phase analysis data obtained at lower temperature.Implications to the formation temperature range and thermal stability of this phase and alloy solidification are discussed based on the calculated Mg-Nd-Ag phase diagram and Scheil solidification paths of alloys.

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“…Since the alloy is designed to be implanted in the human body, like bone screw, the biological safety is greatly important for designing consideration, which means to select bio-functional elements with non-toxicity and degradation. In previous works, researchers [16][17][18][19][20] found that the addition of some biological functional elements such as Ca, Sr, Zn and Ag could benefit by not only refining alloy grain size, but also playing the role of solid solution strengthening, age hardening and sterilization. Du et al [21] reported that the addition of the alloying element Ca inhibited dynamic recrystallization and grain growth and promoted dynamic precipitation during the extrusion process, which raised the yield strength of Mg-6Zn from 125 MPa to 230 MPa.…”

Section: Introductionmentioning

confidence: 99%

The Mechanical Properties and Corrosion Resistance of Magnesium Alloys with Different Alloying Elements for Bone Repair

et al. 2018

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In order to make a rational design of magnesium alloys for bone repair, four kinds of Mg alloy ingots were prepared by vacuum induction furnace, namely Mg-3Zn-0.2Ca (wt.%) (ZX30), Mg-3Zn-0.8Zr (wt.%) (ZK30), Mg-3Zn-0.8Zr-0.3Sr (wt.%) (ZKJ300) and Mg-3Zn-0.8Zr-0.3Ca-0.3Ag (wt.%) (ZKXQ3000) alloys. The four ingots were extruded into bar materials through a hot-extrusion process under different temperatures with different extrusion ratios, the mechanical performances and the corrosion behaviors in the simulated body fluid (SBF) of the four alloys were investigated, and the mechanism of fracture and corrosion was characterized by scanning electron microscopy (SEM). The results showed the ultimate compressive strength (UCS) of all the alloys were found to be around 360 MPa, while ultimate tensile strengths (UTS) of ZKJ300 (334.61 ± 2.92 MPa) and ZKXQ3000 (337.56 ± 2.19 MPa) alloys were much higher than those of ZX30 (298.17 ± 0.93 MPa) and ZK30 (293.26 ± 2.71 MPa) alloys. The electrochemical noise and immersion tests in the SBF indicated that ZK30 alloy performed better in corrosion resistance.

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Effect of Ag addition on microstructure and mechanical properties of Mg–14Gd–0.5Zr alloy

Cited by 36 publications

References 35 publications

Effect of Ag Addition on the Hot Deformation, Constitutive Equations and Processing Maps of a Hot Extruded Mg-Gd-Y Alloy

Effect of Ag Addition on the Hot Deformation, Constitutive Equations and Processing Maps of a Hot Extruded Mg-Gd-Y Alloy

On the Equilibrium Intermetallic Phase in Mg-Nd-Ag Alloys

The Mechanical Properties and Corrosion Resistance of Magnesium Alloys with Different Alloying Elements for Bone Repair

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