Key Laboratory of Light Alloy Preparation and Processing in Nanchang City

Nanchang, China

Key Laboratory of Light Alloy Preparation and Processing in Nanchang City

Nanchang, China
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Yan H.,Nanchang University | Yan H.,Key Laboratory of Light Alloy Preparation and Processing in Nanchang City | Rao Y.,Nanchang University | Rao Y.,Key Laboratory of Light Alloy Preparation and Processing in Nanchang City | And 2 more authors.
Journal of Materials Processing Technology | Year: 2014

The application of ultrasonic vibration treatment (UVT) produced a nearly non-dendritic and refined semi-solid microstructure of Mg2Si/AM60 composite. The effects of UVT temperature and time on microstructure of the semi-solid slurry were studied. A good semi-solid slurry with average grain size of 75 μm and shape coefficient of 0.53 could be obtained by applying UVT at 620 C for 60 s, which were decreased by a factor of 17/20 and increased by a factor of 3 respectively as compared to the sample without treatment. The Mg2Si and Mg17Al12 intermetallics are mainly located along the grain boundaries or dispersed uniformly in the metallic liquid matrix with network morphology. Mechanisms involved in the development of microstructure are discussed. © 2013 Elsevier Inc. All rights reserved.


Chen X.-H.,Nanchang University | Chen X.-H.,Key Laboratory of Light Alloy Preparation and Processing in Nanchang City | Yan H.,Nanchang University | Yan H.,Key Laboratory of Light Alloy Preparation and Processing in Nanchang City
International Journal of Cast Metals Research | Year: 2015

Aluminium alloy matrix composites reinforced with 0.5, 1.0, 1.5 and 2.5 wt-% nanoparticle Al2O3 were fabricated by low frequency mechanical vibration combined with multi-frequency ultrasonic treatment. A microstructural study was carried out by optical, scanning electron and transmission electron microscopy and X-ray diffraction. The effect of reinforcements on the microstructural feature of the composites was investigated. Tensile and compression tests were carried out in order to identify the mechanical properties. The results of the microstructural study revealed a uniform distribution of nanoparticles in the matrix and dendrite refinement of the matrix alloy. It was also found that adding reinforcement content beyond 1.5 wt-% led to an increase in dendrite size values. Compared to the 7075 alloy, the yield strength, ultimate tensile strength and 0.2 compressive yield strength of 1.5 wt-% nano-Al2O3/7075 composite were increased by 74%, 57% and 100% respectively. The improved mechanical properties were due to particle pushing dendrite refinement and particle strengthening. © 2016 W. S. Maney & Son Ltd.


Li Z.,Nanchang University | Li Z.,Key Laboratory of Light Alloy Preparation and Processing in Nanchang City | Yan H.,Nanchang University | Yan H.,Key Laboratory of Light Alloy Preparation and Processing in Nanchang City
Journal of Rare Earths | Year: 2015

The study systematically investigated the effects of master alloy addition containing rare earth elements La and Yb on the microstructures characteristic and tensile properties of AlSi10Cu3 alloy. It was studied by means of optical microscopy, X-ray diffraction, scanning electron microscopy, energy diffraction spectrum and differential thermal analyzer. The results showed that the addition of (La+Yb) obviously reduced the sizes of the primary α-Al phase and eutectic Si particles as well as β-Al5FeSi phase and improved the morphology of the primary α-Al phase and eutectic Si particles. The optimum addition of (La+Yb) addition was 0.6 wt.%. Comparing the 0.6 wt.% (La+Yb) modified AlSi10Cu3 alloy with the unmodified alloy, it was found that the mean diameter, mean area and SADS of primary α-Al phase were decreased by 50.80%, 75.74% and 50.83% respectively; the aspect ratio, size (length) and mean area of eutectic Si particles were decreased by 66.30%, 81.78% and 78.99%, respectively, and the average size of the β-Al5FeSi phase was 16.4 μm. In addition, the addition of (La+Yb) greatly improved the tensile properties of AlSi10Cu3 alloy, especially in the ultimate tensile strength and elongation as a result of the significant improvement in microstructure. © 2015 The Chinese Society of Rare Earths.


Yan H.,Nanchang University | Yan H.,Key Laboratory of Light Alloy Preparation and Processing in Nanchang City | Wang Z.,Nanchang University | Wang Z.,Key Laboratory of Light Alloy Preparation and Processing in Nanchang City
Journal of Rare Earths | Year: 2016

The influence of heat treatment (T6) on the ambient temperature dry sliding wear behavior of the extruded AZ91 alloy treated with Y using a pin-on-disc apparatus was investigated. Wear rates and friction coefficients were measured within a load range of 5-70 N at a sliding speed of 0.188 m/s over a constant sliding distance of 226.195 m. Worn surfaces and debris were examined using a scanning electron microscope equipped with an energy dispersive spectrometer. The experimental results revealed that, as applied load was increased, the alloy wear rates increased, but the friction coefficients decreased. Four chief operating wear mechanisms were observed, i.e., abrasion, oxidation, delamination and plastic deformation. The extruded AZ91 alloy treated with Y exhibited better wear resistance by adopting T6, which was mainly due to large amounts of fine Mg17Al12 distributed in the grains and the resulting modified strength and micro-hardness. © 2016 The Chinese Society of Rare Earths.


Rao Y.-S.,Nanchang University | Rao Y.-S.,Key Laboratory of Light Alloy Preparation and Processing in Nanchang City | Yan H.,Nanchang University | Yan H.,Key Laboratory of Light Alloy Preparation and Processing in Nanchang City | And 2 more authors.
Rare Metals | Year: 2015

The rheological behavior of semisolid Mg2Si/AM60 composites prepared by ultrasonic vibration treatment was investigated. The effects of primary α-Mg solid content, the ultrasonic power and the content of reinforcement phase Mg2Si on the apparent viscosity of semisolid composites were discussed. The results show that the apparent viscosity of the semisolid composites increases with the increase in α-Mg solid content. Meanwhile, the apparent viscosity decreases with the increase in ultrasonic power, and the reduction amplitude is higher when the solid content is higher. In addition, the apparent viscosity increases with the increase in Mg2Si content. Based on experimental data fitting, the rheological model of semisolid Mg2Si/AM60 composites prepared by ultrasonic vibration was established. © 2015 The Nonferrous Metals Society of China and Springer-Verlag Berlin Heidelberg


Chen X.-H.,Nanchang University | Chen X.-H.,Key Laboratory of Light Alloy Preparation and Processing in Nanchang City | Yan H.,Nanchang University | Yan H.,Key Laboratory of Light Alloy Preparation and Processing in Nanchang City
Journal of Materials Research | Year: 2015

Nanosized Al2O3 (Al2O3np) reinforced Al7075 composites were fabricated by specially made Al2O3np containing Mg powder and subtype multifrequency ultrasonic vibration. Compared to traditional techniques, Al2O3np was effectively dispersed in the matrix by the novel method. Microstructural studies showed that the addition of Al2O3np caused the grain refinement and that the resultant microstructures of composites depended on the dominant size and degree of Al2O3np clustering. The grain refinement could be mainly attributed to particle pushing mechanisms. Compared to the matrix alloy, the ultimate tensile and compressive strength of the as-cast composite with 1.5 wt% Al2O3np fabricated at 800 °C were increased by 59.6% and 42.6%, respectively. Transmission electron microscope analysis showed that high density dislocations and clear interfaces between particles and matrix were present in the grains, suggesting that the superior improvement of mechanical properties can be attributed to dislocation-type strengthening of matrix alloy and load transfer from matrix to hard nanoparticles. Copyright © Materials Research Society 2015.


Huang W.,Nanchang University | Huang W.,Key Laboratory of Light Alloy Preparation and Processing in Nanchang City | Huang W.,Jinggangshan University | Yan H.,Nanchang University | Yan H.,Key Laboratory of Light Alloy Preparation and Processing in Nanchang City
Journal of Rare Earths | Year: 2014

Semi-solid Al2Y/AZ91 magnesium matrix composites slurry was prepared by ultrasonic vibration, effect of ultrasonic vibration temperature and time on microstructure of semi-solid slurry was investigated. The results showed that with the ultrasonic vibration temperature decreasing the solid volume fraction of semi-solid slurry increased. The best ultrasonic vibration temperature was 600 °C. With the increase of ultrasonic vibration time, the average grain diameter of primary a-Mg particles decreased firstly, then increased, the average shape factor increased gradually and decreased slightly after 90 s, and a few rosette dendrites were observed after 120 s. The best semi-solid slurry with average grain diameter of 75 μm and shape factor of 0.7 were gained after the melt was treated by ultrasonic vibration for about 60 s at near liquidus temperature (600 °C). At last, the microstructure evolution mechanism of semi-solid magnesium matrix composites slurry was analyzed by the theories of thermodynamics and kinetics. © 2014 The Chinese Society of Rare Earths.


Chen X.H.,Nanchang University | Chen X.H.,Key Laboratory of Light Alloy Preparation and Processing in Nanchang City | Yan H.,Nanchang University | Yan H.,Key Laboratory of Light Alloy Preparation and Processing in Nanchang City | And 2 more authors.
International Journal of Cast Metals Research | Year: 2015

In the present research, aluminium metal matrix composites (AMMCs) with different weight percentages of TiAl3 particles were fabricated by in situ stir casting process. A heterogeneous nucleation phenomenon in the cast AMMCs was studied. Microstructural characterisation was investigated by optical microscopy, X-ray diffraction and scanning electron microscopy. Tensile test was carried out in order to identify the mechanical properties of composites after aging. The primary aluminium phase which nucleated heterogeneously on TiAl3 particles has been identified with a small lattice disregistry while their crystallographic orientation relationship was (001)TiAl3 // (100)Al. The microstructure analysis revealed uniform distribution of reinforcements, grain refinement and clean TiAl3/Al interface in specimens. The mechanical results showed that the addition of up to 1 wt-%Ti led to an improvement in the tensile strength and ductility as compared against matrix. Fractography of the specimens showed that the fracture surfaces of as cast composite exhibited mixed rupture characteristics of quasi-cleavage and tough. © 2015 W. S. Maney & Son Ltd.


Huang B.-H.,Nanchang University | Huang B.-H.,Key Laboratory of Light Alloy Preparation and Processing in Nanchang City | Yan H.,Nanchang University | Yan H.,Key Laboratory of Light Alloy Preparation and Processing in Nanchang City
Chinese Rare Earths | Year: 2015

The effects of heat treatment on microstructure and mechanical properties of extruded AZ61-x% La magnesium alloy were investigated by optical microscope (OM), scanning electron microscope (SEM), X-ray diffraction (XRD)as well as tensile testing. The results showed that, after the T6 treatment, the β-Mg17Al12 phases dispersed around the grain boundary suffered completely dissolved re-precipitated and re-distributed around the grain boundaries; the morphology of β-Mg17Al12 phase changed from network to blocky. In addition, some fine block B phases were also observed in the region of grain. Rare earth phase could refine grains and significantly improve the hardness of the alloy. However, after T6 treatment, hardness was decreased even though the tensile strength, yield strength and elongation of alloy has increased. Meanwhile, T5 treatment has less effect on the mechanical properties of the alloy. ©, 2015, Editorial Office of Chinese Rare Earths. All right reserved.


Chen X.-H.,Nanchang University | Chen X.-H.,Key Laboratory of Light Alloy Preparation and Processing in Nanchang City | Yan H.,Nanchang University | Yan H.,Key Laboratory of Light Alloy Preparation and Processing in Nanchang City
Materials and Design | Year: 2016

Interactions between the solidification front and the remaining suspended particles take place during solidification of particles reinforced composites. The particles are either engulfed by the solidification front or pushed by the solid-liquid interface. In this study, the relation of distribution and clustering degree of nano-Al2O3 in Al7075 with the microstructure of alloy was investigated by conducting casting experiment. A hydrodynamic model for calculating the critical interface velocity required to push nano-particles by the interface was proposed. In addition, the influence of the nano-particles present ahead of solidification front on interface shape was discussed. Microstructural studies showed that the resulting microstructures of composites depended on the size and degree of nano-Al2O3 clustering. Based on the model, it was found that for particles below approximately 36% of the critical radius, r < 0.36 r* = 0.9973 μm, the critical interface velocities were four orders of magnitude lower than those obtained by micron particles, suggesting that smaller particles are easily engulfed by the interface rather than pushed. The experimental results were validated by the prediction of the model. Result showed that the constitutional super-cooling of local melts and the accumulation of solute behind the particle caused formation of a cellular interface. © 2016 Elsevier Ltd.

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