Microstructure evolution of a SIMA processed AZ91D magnesium alloy based on repetitive upsetting-extrusion (RUE) process

Xu, Yan; Hu, Lianxi; Jia, Jianbo; Xu, Bingjie

doi:10.1016/j.matchar.2016.06.011

Cited by 35 publications

(17 citation statements)

References 39 publications

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“…Thus, the remelting behavior may start at Al-rich regions and no grain boundaries were wetted in the Al-poor areas when the temperature was below the solidus temperature, which could account for the inhomogeneous remelting microstructure at grain boundaries illustrated in Figure 4b inhomogeneous microstructure appeared in all three of the RE added alloys when the isothermal treatment was conducted at 570 °C for 5 min (as indicated by red arrows in Figure 4b-d) because the liquid phase was not infiltrated along the boundaries. This was similar to the investigation of the microstructure evolution during reheating of the extruded Mg-Al-Zn alloy by Kleiner et al [16]. As is well known, the initial liquid phase mainly originated from the melting of some low-melting point precipitates, which occurred at the triple points of grain boundaries firstly.…”

Section: Effect Of Y Addition On the Microstructure Evolution During supporting

confidence: 85%

“…It can be seen that some adjacent solid grains were interconnected to form bigger ones, as indicated by blue arrows in Figure 6. This was also demonstrated by Xu et al [16] and Chen et al [29] for the research on the semi-solid microstructure evolution of RUE-formed and ECPA-formed AZ91D alloy, and they suggested that the Ostwald ripening mechanism and the coalescence of solid particles operated simultaneously and independently for the grain coarsening.…”

Section: Effect Of Y Addition On the Microstructure Evolution During supporting

confidence: 53%

“…The results showed that the high-quality semisolid billets with fine and spherical solid particles can be successfully prepared by isothermally treating the ECAE-processed alloy. In addition, repetitive upsetting-extrusion (RUE) was employed by Xu et al [16] as the SIMA process to AZ91D magnesium alloy; it was found that the subsequent semi-solid feedstock with an ideal structure contains highly spherical and homogeneous solid grains. However, these methods are hard to apply in industrial production due to complex operations.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Y Addition on the Semi-Solid Microstructure Evolution and the Coarsening Kinetics of SIMA AZ80 Magnesium Alloy

Tang

Sun

Zhou

et al. 2017

Metals

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Semi-solid feedstock of AZ80 magnesium alloy modified by trace rare-earth Y element (0, 0.2, 0.4, 0.8 wt. %) was fabricated by strain-induced melting activation (SIMA) in the form of extrusion and partial remelting. The effect of Y addition on the microstructure evolution of the extruded and isothermally heat treated alloy was observed by using an optical microscope (OM), scanning electron microscope (SEM), X-ray diffraction (XRD) and quantitative analysis. The results show that the Y addition can refine the microstructure and make the β-Mg 17 Al 12 phases agglomerate. During the subsequent isothermal treatment at 570 • C, the average solid grain size, shape factor and liquid fractions increased with the prolonged soaking time. The smaller spheroidal solid grains and larger shape factor were obtained in the semi-solid microstructure due to Y addition. The coalescence and Ostwald ripening mechanism operated the coarsening process of solid grains simultaneously. The coarsening rate constants of AZ80M1 (0.2 wt. % Y addition) of 164.22 µm 3 ·s −1 was approximately four times less than the un-modified AZ80 alloy of 689.44 µm 3 ·s −1 . In contrast, the desirable semi-solid structure featured, with fine and well globular solid grains, an appropriate liquid fraction, and shape factor was achieved in AZ80M1 alloy treated at 570 • C for 20-30 min.

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Section: Effect Of Y Addition On the Microstructure Evolution During supporting

confidence: 85%

Section: Effect Of Y Addition On the Microstructure Evolution During supporting

confidence: 53%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Effect of Y Addition on the Semi-Solid Microstructure Evolution and the Coarsening Kinetics of SIMA AZ80 Magnesium Alloy

Tang

Sun

Zhou

et al. 2017

Metals

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“…Semi-solid metal process (SSMP) developed by Spencer and co-workers has been widely studied in recent years, which is an effective near-net-shape forming process [1][2][3][4]. Compared with conventional casting and forging processes, it offers significant advantages, such as easy forming, long die life, good microstructure and good mechanical properties [5].…”

Section: Introductionmentioning

confidence: 99%

“…The key requirement of SSMP process is that the semi-solid billet with fine and spherical solid grains uniformly distributed in the liquid phase. To prepare ideal semi-solid microstructures, many methods have been developed, such as, mechanical and electromagnetic stirring [6,7], cooling slope [8], mechanical vibration [9], strain-induced melt activation (SIMA) [2,10], and recrystallization and partial melting (RAP) [11]. Among these methods, RAP process consists of warm deformation and semi-solid isothermal treatment (SSIT) is a promising method, because that many alloys are always supplied in the deformed state.…”

Section: Introductionmentioning

confidence: 99%

Microstructure of Semi-Solid 6063 Alloy Fabricated by Radial Forging Combined with Unidirectional Compression Recrystallization and Partial Melting Process

Wang

Zhao

2017

MATEC Web Conf.

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Abstract. Radial forging combined with unidirectional compression (RFCUM) is introduced in recrystallization and partial melting (RAP) to fabricate semi-solid 6063 aluminum alloy, which can be defined as a process of RFCUM-RAP. In this study, the microstructures of semi-solid 6063 alloy prepared by semi-solid isothermal treatment (SSIT) and RFCUM-RAP processes are investigated. The results show that, the solid grains of semi-solid alloy prepared by SSIT are large and irregular. However, solid grains of semi-solid billet prepared by RFCUC-RAP are fine and spherical. Additionally, during RFCUC-RAP process, with the increase of isothermal holding time, the shape of solid grain is more and more spherical, but the size of solid grain is gradually increased. To obtain ideal semi-solid microstructure, the optimal isothermal holding temperature and time are 630 °C and 5~10 min, respectively.

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Mechanical Response and Microstructure Evolution of a Repetitive Upsetting Extrusion Processed AZ61 Magnesium Alloy in Semi‐Solid Compression

Zhang

et al. 2019

Adv Eng Mater

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Semi‐solid billets of an AZ61 magnesium alloy are prepared by a repetitive upsetting‐extrusion (RUE)‐based strain induced melt activation (SIMA) method. Mechanical response and microstructure evolution in compression of the semi‐solid slurry with high solid fraction are investigated. The results reveal that the SIMA‐processed thixotropic structure comprises of globular solid particles and liquid films. True stress–true strain curves experience a rapid increase to the peak within a small strain, a slow decline, and the final steady‐state flow. Three regions of the dense deformation region, the severe deformation region, and the free deformation region are detected in the compressed specimen with reference to microstructure observation. Liquid segregation is found in the free deformation region due to the exudation of the liquid phase. The compression of the semi‐solid slurry is achieved by the coordination of the solid particles’ rearrangement and the liquid flow. The initial deformation stage is governed by the sliding or rotating of the solid particles. Mechanisms of the sliding between solid particles and the plastic deformation of the solid particles are responsible for the second and the final deformation stages, and their relative contribution is closely related to the solid fraction and deformation strain.

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Microstructure evolution of a SIMA processed AZ91D magnesium alloy based on repetitive upsetting-extrusion (RUE) process

Cited by 35 publications

References 39 publications

Effect of Y Addition on the Semi-Solid Microstructure Evolution and the Coarsening Kinetics of SIMA AZ80 Magnesium Alloy

Effect of Y Addition on the Semi-Solid Microstructure Evolution and the Coarsening Kinetics of SIMA AZ80 Magnesium Alloy

Microstructure of Semi-Solid 6063 Alloy Fabricated by Radial Forging Combined with Unidirectional Compression Recrystallization and Partial Melting Process

Mechanical Response and Microstructure Evolution of a Repetitive Upsetting Extrusion Processed AZ61 Magnesium Alloy in Semi‐Solid Compression

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