Microstructure evolution during heat treatment of Mg–Gd–Y–Zn–Zr alloy and its low-cycle fatigue behavior at 573 K

Wu, Lijun; Li, Hao-tian; Yang, Zhong

doi:10.1016/s1003-6326(17)60120-1

Cited by 17 publications

(5 citation statements)

References 38 publications

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“…By taking a closer look at the microstructure around the indents, imprinted grains without LPSO lamellae consist of more blocky LPSO phases, and the grains are larger than the indent size, so the imprint is not affected by grain boundaries. Furthermore, imprints in grains with lamellar LPSO phases are of larger size than the grain itself, so micro-cracks are inclined to nucleate and propagate at the grain boundaries as well as at lamellar LPSO/Mg-matrix interface, as seen in [32]. This behavior is most pronounced in the heat-treated condition for 48 h, which also supports the highest fracture toughness: sub-cracks form more easily, which extends the crack length and absorbs energy.…”

Section: Discussionmentioning

confidence: 69%

“…While some microstructural features cause crack initiation under mechanical loading or stress corrosion [27], these features also hinder crack propagation and increase the fracture toughness: low angle grain boundaries [28], twinned grains [29,30], second phases [28], LPSO structures [31,32], and crystallographic planes [33]. Charpy tests [34], slow rate tensile tests [35] or U-bent tests [36] are often used to determine the fracture toughness under stress corrosion.…”

Section: Introductionmentioning

confidence: 99%

“…Cracks can pass through grain boundary (gb) LPSO phases into the adjacent grain. The generation of cavities and crack blunting was observed when the cracks propagation direction deviated remarkably from the orientation of the LPSO slip bands [32].…”

Section: Introductionmentioning

confidence: 99%

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Crack Propagation in As-Extruded and Heat-Treated Mg-Dy-Nd-Zn-Zr Alloy Explained by the Effect of LPSO Structures and Their Micro- and Nanohardness

et al. 2021

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The investigation of the crack propagation in as-extruded and heat-treated Mg-Dy-Nd-Zn-Zr alloy with a focus on the interaction of long-period stacking-ordered (LPSO) structures is the aim of this study. Solution heat treatment on a hot extruded Mg-Dy-Nd-Zn-Zr (RESOLOY®) was done to change the initial fine-grained microstructure, consisting of grain boundary blocky LPSO and lamellar LPSO structures within the matrix, into coarser grains of less lamellar and blocky LPSO phases. C-ring compression tests in Ringer solution were used to cause a fracture. Crack initiation and propagation is influenced by twin boundaries and LPSO lamellae. The blocky LPSO phases also clearly hinder crack growth, by increasing the energy to pass either through the phase or along its interface. The microstructural features were characterized by micro- and nanohardness as well as the amount and location of LPSO phases in dependence on the heat treatment condition. By applying nanoindentation, blocky LPSO phases show a higher hardness than the grains with or without lamellar LPSO phases and their hardness decreases with heat treatment time. On the other hand, the matrix increases in hardness by solid solution strengthening. The microstructure consisting of a good balance of grain size, matrix and blocky LPSO phases and twins shows the highest fracture energy.

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Section: Discussionmentioning

confidence: 69%

Section: Introductionmentioning

confidence: 99%

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Crack Propagation in As-Extruded and Heat-Treated Mg-Dy-Nd-Zn-Zr Alloy Explained by the Effect of LPSO Structures and Their Micro- and Nanohardness

et al. 2021

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“…The solute partition coefficients of RE elements and other solute elements are all less than 1, so they are easy to be enriched at solid-liquid interface during solidification [35]. With the decrease of cooling rate, the diffusion distance of solute elements becomes longer [36], resulting in the weakening of the enrichment degree of solute elements. The weaker the enrichment is, the lower the content of solute is.…”

Section: Discussionmentioning

confidence: 99%

Effect of cooling rate on microstructure and mechanical properties of Mg-9Gd-4Y-1Zn-1Al alloy

Wang

Feng

et al. 2023

Materials Science and Technology

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In this paper, the effect of cooling rate on solidification behaviour, microstructure evolution and mechanical properties of Al-refined Mg-9Gd-4Y-1Zn was studied. As cooling rate decreased, grain size increased and when cooling rate was 32.5°C/s, grain size was the smallest (30.57 µm). The second phases included lamellar LPSO, block-like Mg3 (Zn, RE), granular Al2RE and acicular Al2RE. As cooling rate decreased, the content of granular Al2RE increased, while that of other phases decreased. As cooling rate decreased, ultimate tensile strength (UTS), yield strength (YS) and elongation all decreased. When cooling rate was 32.5°C/s, the mechanical properties were the best, and UTS, YS and elongation were 228.2 MPa, 158.2 MPa and 8.8%, respectively.

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“…High strength Mg–Gd–Y–Zn–Zr series rare-earth magnesium alloys will generate LPSO phase after heat treatment, and the existence of LPSO phase has obvious strengthening and toughening effects on the alloy [ 33 ]. Most studies focused on the structure of LPSO phase and its effects on the microstructure and mechanical properties of the alloy [ 34 , 35 ].…”

Section: Introductionmentioning

confidence: 99%

The Formation of 14H-LPSO in Mg–9Gd–2Y–2Zn–0.5Zr Alloy during Heat Treatment

Liu

Yang

et al. 2021

Materials

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There is a new long-period stacking ordered structure in Mg–RE–Zn magnesium alloys, namely the LPSO phase, which can effectively improve the yield strength, elongation, and corrosion resistance of Mg alloys. According to different types of Mg–RE–Zn alloy systems, two transformation modes are involved in the heat treatment transformation process. The first is the alloy without LPSO phase in the as-cast alloy, and the MgxRE phase changes to 14H-LPSO phase. The second is the alloy containing LPSO phase in the as-cast state, and the 14H-LPSO phase is obtained by the transformations of 6H, 18R, and 24R. The effects of different solution parameters on the second phase of Mg–9Gd–2Y–2Zn–0.5Zr alloy were studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The precipitation mechanism of 14H-LPSO phase during solution treatment was further clarified. At a solution time of 13 h, the grain size increased rapidly initially and then decreased slightly with increasing solution temperature. The analysis of the volume fraction of the second phase and lattice constant showed that Gd and Y elements in the alloy precipitated from the matrix and formed 14H-LPSO phase after solution treatment at 490 °C for 13 h. At this time, the hardness of the alloy reached the maximum of 74.6 HV. After solution treatment at 500 °C for 13 h, the solid solution degree of the alloy increases, and the grain size and hardness of the alloy remain basically unchanged.

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Microstructure evolution during heat treatment of Mg–Gd–Y–Zn–Zr alloy and its low-cycle fatigue behavior at 573 K

Cited by 17 publications

References 38 publications

Crack Propagation in As-Extruded and Heat-Treated Mg-Dy-Nd-Zn-Zr Alloy Explained by the Effect of LPSO Structures and Their Micro- and Nanohardness

Crack Propagation in As-Extruded and Heat-Treated Mg-Dy-Nd-Zn-Zr Alloy Explained by the Effect of LPSO Structures and Their Micro- and Nanohardness

Effect of cooling rate on microstructure and mechanical properties of Mg-9Gd-4Y-1Zn-1Al alloy

The Formation of 14H-LPSO in Mg–9Gd–2Y–2Zn–0.5Zr Alloy during Heat Treatment

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