Microstructures, corrosion and mechanical properties of as-cast Mg–Zn–Y–(Gd) alloys

Shi, Fei; Wang, Chunqing; Zhang, Zhongming

doi:10.1016/s1003-6326(15)63829-8

Cited by 54 publications

(24 citation statements)

References 22 publications

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“…This means the gray microstructure is eutectic Mg and the Zn/RE ratio (at.%) of the lamellar white eutectic phase was close to 1.5, suggesting that the white lamellar eutectic phase is the W phase. This is in accordance with the XRD results [33,34].…”

Section: Resultssupporting

confidence: 92%

The Influence of Holding Time on the Microstructure Evolution of Mg–10Zn–6.8Gd–4Y Alloy during Semi-Solid Isothermal Heat Treatment

Nie

Gao

Wang

et al. 2019

Metals

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A semi-solid microstructure of Mg–10Zn–6.8Gd–4Y alloys is acquired via an isothermal heat treatment process, and the effects of the holding time on the microstructure evolution of Mg–10Zn–6.8Gd–4Y alloys are investigated. The results show that the microstructure of the cast alloy is composed of primary α-Mg dendritic grains with a eutectic structure (W-phase and eutectic Mg) distributed at the grain boundaries. The primary α-Mg dendritic grains grow in size with increasing holding time, and they tend to grow into more globular structures in the initial stage; they then become a bit more dendritic, as small branches grow from the grain boundaries after holding the sample at 580 °C for 10 min. Meanwhile, the interdiffusion of magnesium atoms within the eutectic region, and between the primary α-Mg and eutectic structure, leads to the formation of fine and relatively globular eutectic Mg grains in the eutectic structure after holding for 10 min. The eutectic Mg grains begin to grow, coarsen, coalesce, or be swallowed by the surrounding primary grains, causing fluctuations of the general grain size. Over the whole isothermal heat treatment process, two mechanisms—coalescence and Ostwald ripening—dominate the grain coarsening.

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Section: Resultssupporting

confidence: 92%

The Influence of Holding Time on the Microstructure Evolution of Mg–10Zn–6.8Gd–4Y Alloy during Semi-Solid Isothermal Heat Treatment

Nie

Gao

Wang

et al. 2019

Metals

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“…The potential engineering applications of magnesium alloy are thus hindered, due to this poor corrosion resistance [2][3][4][5].…”

Section: Introductionmentioning

confidence: 99%

Formation Process of an LDHs Coating on Magnesium Alloy by a CO2 Pressurization Method

et al. 2019

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The formation process of LDHs (layered double hydroxides) coating on magnesium alloy by the CO2 pressurization method was studied. The micro-structure was observed by OM, SEM and GAXRD. The weighted gain curve, apparent activation energy, and CO2 solubility curve were all calculated by equations. The potentiodynamic polarization curve, hydrogen evolution data, and immersion were analyzed by an electrochemical method. The results show that the LDHs coating was formed layer-by-layer. The formation positions were initially on the α-Mg phase, and then on the β-Mg17Al12 phase. It was found to be the most compact after 30 min. The LDHs coating began to appear to have severe cracks and holes over time. The formation process of the LDHs coating can be divided into three stages: a rapid growth stage (0–10 min), slow growth stage (10–20 min), and periodic growth stage (30 min, 1 h). The apparent activation energies in each of the three stages are 21.78, 31.86 and 34.92 kJ mol−1, respectively. The LDHs coating has a compact micro-structure and better anti-corrosion at a pressure of 3 MPa, a temperature of 50 °C and a time of 30 min. The CO2 pressurization promotes a formation reaction rate and achieves a high formation efficiency and good formation stability under the condition of zero pollution.

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“…The β-phase melting point was reported to be 437 • C [48]. Therefore, at 480 • C, the grain boundary segregations dissolved to the solid solution and re-precipitated in the form of thin elongated β-phase particles, which can for this material be characterised as Mg 17 (AlZnDy) 12 . This significant change is also advantageous for mechanical properties since grain boundary segregations of brittle Mg 17 (Al) 12 -type phases have repeatedly been reported to deteriorate strength, as well as the plasticity of Mg-based alloys [19,48,49].…”

Section: Discussionmentioning

confidence: 99%

“…The alloying elements can positively affect the mechanical properties of Mg-based alloys in many ways: for example, by grain refinement, solid solution strengthening, and precipitation hardening [16,17]. Aluminium, a common alloying element, provides strengthening via solid solution and precipitation of secondary phases, especially Mg 17 Al 12 [18,19].…”

Section: Introductionmentioning

confidence: 99%

Comprehensive Characterisation of a Newly Developed Mg–Dy–Al–Zn–Zr Alloy Structure

Kunčická

Kocich

2018

Metals

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This is a report on the structure phases and precipitates in a newly developed Mg-10Dy-3Al-1Zn-0.2Zr alloy. Specimens from the cast alloy were heat treated at temperatures of 480 • C, 520 • C and 560 • C, all for 8 and 16 h, and subsequently quenched. The structures were then analysed using scanning and transmission electron microscopy, while the mechanical properties were investigated using microhardness measurements. The results showed the different temperatures, as well as times, influence both the chemical composition and morphology of the precipitated phases. The occurrence of the β-phase changed with increasing temperature and time from grain boundary segregations through fine elongated particles to coarse plate-like precipitates. Polygon-shaped Dy-rich precipitates were observed in all the samples; however, their size decreased and their distribution homogenised with increasing annealing temperature and time. The samples annealed at 520 • C and 560 • C exhibited the presence of lamellar 18R-type long period stacking ordered (LPSO) phases. Microhardness measurements were in accordance with results of the microscopic analyses; although the values varied between 60 and 65 HV for all the material states, the most uniform distribution was observed for the 560 • C/8-h sample, which featured the finest precipitates and LPSO phases.

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Microstructures, corrosion and mechanical properties of as-cast Mg–Zn–Y–(Gd) alloys

Cited by 54 publications

References 22 publications

The Influence of Holding Time on the Microstructure Evolution of Mg–10Zn–6.8Gd–4Y Alloy during Semi-Solid Isothermal Heat Treatment

The Influence of Holding Time on the Microstructure Evolution of Mg–10Zn–6.8Gd–4Y Alloy during Semi-Solid Isothermal Heat Treatment

Formation Process of an LDHs Coating on Magnesium Alloy by a CO2 Pressurization Method

Comprehensive Characterisation of a Newly Developed Mg–Dy–Al–Zn–Zr Alloy Structure

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