Influence of secondary phases on crack initiation and propagation during fracture process of as-cast Mg-Al-Zn-Nd alloy

Cui, Xiaoming; Yu, Zhilei; Liu, Fei; Du, Zhongjie; Bai, Peng

doi:10.1016/j.msea.2019.05.062

Cited by 26 publications

(7 citation statements)

References 24 publications

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“…As shown in figure 1(a), many coarse Mg 17 Al 12 phases are distributed at the grain boundaries and then dissolved in the matrix after homogenization (figure 1(b)). In our previous study, the residual precipitate phase particles should be rareearth-containing phases [22,24].…”

Section: Resultsmentioning

confidence: 90%

“…Therefore, rare earth compounds also play a positive role in improving the plasticity of the alloy. The authors [21,22] studied the microstructure evolution and mechanical properties of Mg-Al-Zn-Nd casting alloy in the early stage. They found small-sized high-melting Al-Nd compounds in the alloy, which can hinder the dislocation movement and play the role of secondary phase strengthening.…”

Section: Introductionmentioning

confidence: 99%

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Effect of twinning and Al–Nd phase on dynamic recrystallization in rolled Mg–Al–Zn–Nd alloy at the moderate strain rate

Cui

Wang

et al. 2021

Mater. Res. Express

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The dynamic recrystallization of Mg-Al-Zn-Nd alloy during moderate strain rate rolling was studied using electron backscatter diffraction (EBSD) and an energy dispersive spectrometer (EDS). The results showed three kinds of twinnings produced in the alloy in the strain rate range of 4.2 s-1 ~ 7.3 s-1, including {101 ̅2} extension twinning, {101 ̅1} contraction twinning, and {101 ̅1}-{101 ̅2} double twinning. The extension twinnings decreased gradually with the increase of strain rate. The dynamic recrystallization mechanisms during hot rolling under moderate strain rate conditions mainly include grain boundary nucleation, twinning nucleation, and secondary particle assistant nucleation. The dynamic recrystallization mechanism induced by twinning is mainly {101 ̅1}-{101 ̅2} double twinnings. In addition, the strain value near the Al-Nd phase and grain boundary is higher than in grain. The Al-Nd particles in Mg-Al-Zn-Nd alloy play an auxiliary nucleation effect on dynamic recrystallization during hot rolling deformation.

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Section: Resultsmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Effect of twinning and Al–Nd phase on dynamic recrystallization in rolled Mg–Al–Zn–Nd alloy at the moderate strain rate

Cui

Wang

et al. 2021

Mater. Res. Express

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“…There are some coarse second phases, which are as a result of the breaking of the bulk phase in the as-cast alloys during extrusion. In the tensile process, the coarse second phase causes stress concentration and develops into a crack source, resulting in a low strength of the alloy [36]. In particular, the addition of Zn allows the bulk phase to be solid-dissolved into the matrix, while promoting the precipitation of small-sized precipitates during extrusion.…”

Section: Discussionmentioning

confidence: 99%

Effect of Zn Content on the Microstructure and Mechanical Properties of Mg–Al–Sn–Mn Alloys

Zhao

Pan

et al. 2019

Materials

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High performance Mg–6Al–3Sn–0.25Mn–xZn alloys (x = 0, 0.5, 1.0, 1.5, and 2.0 wt %) without rare earth were designed. The effects of different Zn contents on the microstructure and mechanical properties were systematically investigated. The addition of Zn obviously refines the as-cast alloys dendritic structure because of the increase in the number in the second phase. For the as-extruded alloys, an appropriate amount of Zn promotes complete recrystallization, thus increasing the grain size. As the Zn content increases, the texture gradually evolves into a typical strong basal texture, which means that the basal slip is difficult to initiate. Meanwhile, the addition of Zn promotes the precipitation of small-sized second phases, which can hinder the dislocation movement. The combination of texture strengthening and precipitation strengthening is the main reason for the improvement of alloys’ strength.

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“…Casting defects and intermetallics are two main factors that promote crack initiation in light alloys [5,20,35]. During the casting process in AC4B alloy, casting defects were closely related with casting techniques especially cooling rate.…”

Section: Crack Initiation Mechanismsmentioning

confidence: 99%

Crack Initiation Mechanism in Casting AC4B Aluminum Alloy Parts with Complex Structure

Yang²,

Deng³

et al. 2021

Metals

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Hot tears were frequently formed in Aluminum (Al) parts with complex structure. In this study, OM (optical microscope), SEM (scanning electron microscope), EDS (energy dispersive spectrometer), and FDM (finite difference method) were used to reveal the hot tears mechanisms in the casted AC4B Al engine. Shrinkage porosities with the size of 300–500 μm were found in casted specimens near the parts’ surface. Many cracked brittle Fe-bearing phase were also found in crack section. The secondary dendrite arm spacing observation in five typical positions showed that the cooling rate in position 5 was faster than that in position 1. The impropriety solidification sequence in position 5 and position 1 impeded the solidification feeding of position 1, and it might lead to casting defects or even casting cracks. Numerical simulation also showed that solidification sequence promoted casting defects, which was accordant with microstructure observation. Impurity may concentrate at position 5 during filling. It is concluded that large β-Fe intermetallics and improper solidification sequence together contributed to crack initiation in the engine.

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Influence of secondary phases on crack initiation and propagation during fracture process of as-cast Mg-Al-Zn-Nd alloy

Cited by 26 publications

References 24 publications

Effect of twinning and Al–Nd phase on dynamic recrystallization in rolled Mg–Al–Zn–Nd alloy at the moderate strain rate

Effect of twinning and Al–Nd phase on dynamic recrystallization in rolled Mg–Al–Zn–Nd alloy at the moderate strain rate

Effect of Zn Content on the Microstructure and Mechanical Properties of Mg–Al–Sn–Mn Alloys

Crack Initiation Mechanism in Casting AC4B Aluminum Alloy Parts with Complex Structure

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