Enhanced mechanical properties of as-cast AZ91 magnesium alloy by combined RE-Sr addition and hot extrusion

Afsharnaderi, Aria; Lotfpour, Mehrab; Mirzadeh, Hamed; Emamy, M.; Malekan, Mehdi

doi:10.1016/j.msea.2020.139817

Cited by 66 publications

(20 citation statements)

References 63 publications

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“…[ 42 ] Moreover, the extrusion process led to a remarkable grain refinement of the as‐cast Mg‐0.5Zr‐0.5Ca‐1Zn alloy due to the occurrence of dynamic recrystallization (DRX) during hot working. [ 43,44 ]…”

Section: Resultsmentioning

confidence: 99%

“…[42] Moreover, the extrusion process led to a remarkable grain refinement of the as-cast Mg-0.5Zr-0.5Ca-1Zn alloy due to the occurrence of dynamic recrystallization (DRX) during hot working. [43,44] Backscattered electron (BSE) images are shown in Figure 1g-k. The formation of secondary phases via Zn addition is evident.…”

Section: As-cast and Extruded Microstructuresmentioning

confidence: 99%

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Mechanical Properties and Corrosion Behavior of Biodegradable Mg–0.5Zr–0.5Ca–xZn Magnesium Alloys

et al. 2023

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Mechanical properties and in vitro corrosion behavior of biodegradable Mg–0.5Zr–0.5Ca–xZn alloys in the simulated body fluid (SBF) solution are investigated. Zinc addition leads to a remarkable grain refinement in the as‐cast condition, as well as the formation of Ca2Mg6Zn3 and Mg7Zn3 compounds. As a result, the lean Mg–0.5Zr–0.5Ca–1Zn alloy shows the best combination of mechanical properties with an ultimate tensile strength (UTS) of 182 MPa, total elongation of 9.5%, and tensile toughness of 13 MJ m−3, which reveals ≈80%, 72%, and 190% improvements compared to those obtained for the Mg–0.5Zr–0.5Ca alloy, respectively. This sample also exhibits improved corrosion behavior, where a decrease in the corrosion current density (iCorr) is recorded via the addition of 1 wt% Zn. However, higher Zn additions result in the formation of a quasi‐continuous eutectic network with the consequent deterioration of tensile properties and increased effect of microgalvanic couples. The extreme grain refinement induced by the dynamic recrystallization (DRX) remarkably improves the overall mechanical properties of the hot extruded alloy but increased the iCorr. Accordingly, the properties of Mg–0.5Zr–0.5Ca alloys can be tailored for biomedical applications via Zn addition and thermomechanical processing.

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Section: Resultsmentioning

confidence: 99%

Section: As-cast and Extruded Microstructuresmentioning

confidence: 99%

Mechanical Properties and Corrosion Behavior of Biodegradable Mg–0.5Zr–0.5Ca–xZn Magnesium Alloys

et al. 2023

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“…[9] Solid solution strengthening can better improve the strength of the alloy, but it is often detrimental to the improvement of the ductility of alloy. [10] To improve the properties of magnesium alloy, alloying elements such as rare earth elements [11] and alkaline earth elements [12] are usually added by fine grain strengthening, second phase strengthening, and solid solution strengthening caused by alloying elements. Wang et al [13] found that Al 8 Mn 4 Gd as heterogeneous nucleation particles of α-Mg and Mg 17 Al 12 can refine α-Mg and Mg 17 Al 12 , and improve the properties of alloy by causing fine grain strengthening and second phase strengthening.…”

Section: Introductionmentioning

confidence: 99%

Formation Sequence of Compounds in AZ91‐0.9Ce Alloy and Its Role in Fracture Process

et al. 2022

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AZ91‐0.9Ce alloy with a thickness of 8 mm is prepared by die casting. The formation process of main compounds in the alloy, the role of main compounds in fracture process, the main crack source, and crack propagation path of the alloy are studied. Results show that AZ91‐0.9Ce alloy is mainly composed of α‐Mg matrix, Mg17Al12 compound, Al4Ce compound, and a small amount of Al–Mn–Ce ternary compound. Among them, Al4Ce is formed prior to the Mg17Al12 compound. Mg17Al12 is formed by eutectic reaction, and Al–Mn–Ce ternary compound is formed at a later stage of solidification. Mg17Al12 and Al4Ce are the main crack sources of the alloy during the fracture process. Crack locations in the alloy mainly include grain boundaries, phase boundaries, and Mg17Al12 and Al4Ce compounds. The fracture mechanism of the alloy is that with the increase of load cracks occur at Mg17Al12 and Al4Ce compounds and connect with each other through intergranular and a small amount of transgranular to form the main crack. With the load continues to increase, the main crack gradually expands until alloy fracture failure. The continuous network distribution along grain boundaries of the Mg17Al12 compound is an important reason for intergranular fracture.

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“…In particular, the thermodynamic stability of precipitates formed by rare-earth elements is generally much higher than that of conventional elements 16 . For example, researchers have explored the synthesis of precipitates with good thermodynamic stability by conventional alloying elements, such as Al 2 Ca, Mg 2 Si, and Al 4 Sr, which are formed by adding Ca, Si, and Sr elements, and their melting points are 1079°C 17,18 , 1087°C 19,20 , and 1040°C [21][22][23] , respectively. Although the thermodynamic stability of these precipitates is not bad, that of the precipitates composed of rare-earth elements such as Pr, Nd, Gd, Dy, La, Ce, Y, etc., is much higher.…”

Section: Introductionmentioning

confidence: 99%

Study on the Strengthening Mechanism of Rare-Earth Element Ce on the Laser Welded Joints of Magnesium Alloys

2022

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The thermomechanical stability of majority precipitates formed by conventional alloying elements in magnesium alloys is generally poor. Hence the morphology and structure of these precipitates are highly susceptible to the welding thermal cycle, which results in the softening of the heat-affected zone (HAZ). Rare-earth (RE) precipitates are generally thermodynamically stable. Therefore, it is necessary to conduct an in-depth discussion on whether RE precipitates reduce the softening of the HAZ. In this paper, Ce-containing magnesium alloy was successfully welded by fiber laser welding. Scanning electron microscope (SEM), X-ray diffraction (XRD), energy dispersive spectrometer (EDS), and micro-hardness tester were employed to analyze the welded joints. Consequently, the distribution characteristics of RE precipitates in both fusion zone (FZ) and HAZ were revealed. Moreover, based on the solution experiments of the welded joints, the evolution mechanism of the precipitates in welded joints during the thermal cycle was deduced, and the softening mechanism of the HAZ was clarified. Thereafter, the relative intrinsic mechanism of RE precipitates in reducing the softening of the HAZ and improving the mechanical properties of FZ was explored. The results showed that the HAZ was narrow, with a width of only 100-200 μm. The morphology and distribution of the less thermally stable Mg 17 Al 12 precipitated in HAZ changed significantly after the thermal cycle. In contrast, RE precipitates remained stable, which is extremely important for reducing the softening of the HAZ. In addition, the precipitates in FZ were transformed into micron-sized particles and precipitated at the edge of dendrites, resulting in a hardness improvement of the FZ.

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Enhanced mechanical properties of as-cast AZ91 magnesium alloy by combined RE-Sr addition and hot extrusion

Cited by 66 publications

References 63 publications

Mechanical Properties and Corrosion Behavior of Biodegradable Mg–0.5Zr–0.5Ca–xZn Magnesium Alloys

Mechanical Properties and Corrosion Behavior of Biodegradable Mg–0.5Zr–0.5Ca–xZn Magnesium Alloys

Formation Sequence of Compounds in AZ91‐0.9Ce Alloy and Its Role in Fracture Process

Study on the Strengthening Mechanism of Rare-Earth Element Ce on the Laser Welded Joints of Magnesium Alloys

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