Immiscible alloys gained a considerable interest in last decades due to their valuable properties and potential applications. Many experimental and theoretical researches were carded out worldwide to investigate the s...Immiscible alloys gained a considerable interest in last decades due to their valuable properties and potential applications. Many experimental and theoretical researches were carded out worldwide to investigate the solidification of immiscible alloys under the normal gravity and microgravity condition. The objective of this article is to review the research work in this field during the last few decades.展开更多
Continuous solidification experiments are carried out with Pb–Al alloys under the influence of the electric current pulses（ECPs）. The results demonstrate that the ECPs mainly affect the microstructure formation thr...Continuous solidification experiments are carried out with Pb–Al alloys under the influence of the electric current pulses（ECPs）. The results demonstrate that the ECPs mainly affect the microstructure formation through changing the energy barrier for the nucleation of the minority phase droplets（MPDs） and minority phase particles（MPPs） during cooling Pb–Al alloys in the liquid–liquid and liquid–solid phase transformation temperature ranges in advance of the solidification of the matrix liquid. For Pb–Al alloys with Al-rich droplets/particles as the minority phase, the ECPs lower the energy barriers for the nucleation of the MPDs/MPPs and cause a significant increase in the nucleation rate of the MPDs/MPPs and, thus,promote the formation of Pb–Al alloys with a well-dispersed or even nanoparticles dispersed microstructure. The ECPs parameters show an important influence on the microstructure formation of Pb–Al alloys. The refinement extent of the MPDs/MPPs increases with the increase in the peak current density. For a given peak current density, the refinement extent of the MPDs/MPPs increases with the increases in the pulse frequency and pulse width first, and then level off and become asymptotic.展开更多
The directional solidification has been carried out for the AI-413i-2,5Co （wt pct） alloys with different melt superheat temperatures. The microstructure characterization and the quantitative metallographic analysis ...The directional solidification has been carried out for the AI-413i-2,5Co （wt pct） alloys with different melt superheat temperatures. The microstructure characterization and the quantitative metallographic analysis have been performed. The results indicated that the Bi-rich sphere size and cellular spacing decrease with increasing melt superheat temperature. The interaction between the advancing solidification interface and the Bi-rich spheres with different sizes was analyzed. The effect of the melt superheat treatment on microstructure evolution was discussed for the immiscible alloys. The microstructure development in ternary Al-Bi-Co alloys directionally solidified with different melt superheat temperatures was clarified.展开更多
In this work, a quaternary Ni-Cu-Nb-Ta system has been designed to obtain composite microstructure with sphericalcrystalline Cu-rich particles embedded in amorphous Ni-rich matrix. The alloy samples were prepared by u...In this work, a quaternary Ni-Cu-Nb-Ta system has been designed to obtain composite microstructure with sphericalcrystalline Cu-rich particles embedded in amorphous Ni-rich matrix. The alloy samples were prepared by using single-roller melting-spinning method. The microstructure and thermal properties of the as-quenched alloy samples were char-acterized by X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, anddifferential scanning calorimetry. It shows that the spherical crystalline Cu-rich particles are embedded in the amorphousNi-rich matrix. The average size of the Cu-rich particles is strongly dependent upon the Cu content. The effect of the alloycomposition on the behavior of liquid-liquid phase separation and microstructure evolution was discussed. The phaseformation in the Ni-based metallic glass matrix composite was analyzed.展开更多
The solidified microstructure of immiscible alloys strongly depends on the nucleation, diffusional growth, especially the coalescence of the second phase droplets in the miscibility gap. A numerical model based on the...The solidified microstructure of immiscible alloys strongly depends on the nucleation, diffusional growth, especially the coalescence of the second phase droplets in the miscibility gap. A numerical model based on the discrete multi-particle approach was developed to simulate the nucleation and coalescence mode of the second phase droplets during the earth-based processing of immiscible alloys (in this case, the effect of gravity cannot be neglected). The cooling rate is the major factor influencing the coalescence mode. Under the super-rapid or rapid solidification condition (>104K/s), Brownian collision is the dominant coalescence mode. Marangoni collision becomes the dominant mode under the sub-rapid solidification condition (>102K/s). In the conventional slow cooling scope(101K/s), Stokes collision becomes the dominant coalescence mode, correspondingly, leading to a serious phase segregation.展开更多
Immiscible alloys have aroused considerable interests in the last decades on account of their special physical andmechanical properties and potential applications. A considerable number of researches have been impleme...Immiscible alloys have aroused considerable interests in the last decades on account of their special physical andmechanical properties and potential applications. A considerable number of researches have been implemented toinvestigate the solidification behaviors of immiscible alloys in electric and magnetic fields. It has been indicated that themagnetic field and electric current can remarkably affect the solidification process and microstructures of immisciblealloys. The solidification techniques under the effects of electric and magnetic fields have great potentials for the fabri-cation of immiscible alloys. This paper reviews the research work in this field in recent years.展开更多
Immiscible alloys are attractive for their valuable physical and mechanical properties. In this paper, Al-ln immiscible alloy is prepared by melt spinning process and its morphological evolution is studied at various ...Immiscible alloys are attractive for their valuable physical and mechanical properties. In this paper, Al-ln immiscible alloy is prepared by melt spinning process and its morphological evolution is studied at various indium contents. The results show that the morphologies of the matrix phase depend on the indium content. Different morphologies lead to different distribution of the second phase particles. Due to a particular solidification mechanism of immiscible alloys, even under the melt spinning rapid solidification condition, it is still impossible to produce homogeneous Al-ln hypomonotectic alloy ribbons. But for Al-ln hypermonotectic alloys, there is almost no segregation of the second phase throughout the cross section of the ribbons.展开更多
Immiscible alloys have attracted growing interest for their valuable physical and mechanical properties. However, their production is difficult because of metallurgical problems in which there is a serious tendency fo...Immiscible alloys have attracted growing interest for their valuable physical and mechanical properties. However, their production is difficult because of metallurgical problems in which there is a serious tendency for gravity separation in the region of the miscibility gap. So far the study on the liquid separation mechanism is still one of the important projects in the spatial materials science and the spatial fluid science. The studied results about the liquid phase separating mechanism of immiscible alloys are presented, at the same time the preparation techniques of homogeneous immiscible alloys are summarized, and the existing problems and the related researching areas in the future are also pointed out.展开更多
Using synchrotron X-ray imaging technique,the segregation evolution in solidifying Al-10 wt% Bi immiscible alloys was investigated at different cooling rates.Irrespective of the cooling rate,most of the Bi solute appe...Using synchrotron X-ray imaging technique,the segregation evolution in solidifying Al-10 wt% Bi immiscible alloys was investigated at different cooling rates.Irrespective of the cooling rate,most of the Bi solute appeared at the upper part of the sample after solidification.The reason for this Bi enrichment phenomenon is different for different cooling rates.Besides Marangoni motion,positive segregation,which has rarely been noticed before,can also make Bi solute transfer to the hot top zone.It is also found that,bubbles（or pores） appear in solidifying Al-10 wt% Bi alloys,and the number of bubbles（or pores） increases with the increase of the cooling rate,while the size of the bubbles（or pores） decreases.展开更多
基金financial support from the National Natural Science Foundation of China (Grant Nos. 51271185, 51471173 and 51501207)the China Manned Space Engineering (Grant No. TGJZ800-2-RW024)
文摘Immiscible alloys gained a considerable interest in last decades due to their valuable properties and potential applications. Many experimental and theoretical researches were carded out worldwide to investigate the solidification of immiscible alloys under the normal gravity and microgravity condition. The objective of this article is to review the research work in this field during the last few decades.
基金supported by the National Natural Science Foundation of China(Grant Nos.51771210,51501207,51471173 and 51271185)the China’s Manned Space Station Project(Grant No.TGJZ800-2-RW024)the Natural Science Foundation of Liaoning Province(Grant No.201501043)
文摘Continuous solidification experiments are carried out with Pb–Al alloys under the influence of the electric current pulses（ECPs）. The results demonstrate that the ECPs mainly affect the microstructure formation through changing the energy barrier for the nucleation of the minority phase droplets（MPDs） and minority phase particles（MPPs） during cooling Pb–Al alloys in the liquid–liquid and liquid–solid phase transformation temperature ranges in advance of the solidification of the matrix liquid. For Pb–Al alloys with Al-rich droplets/particles as the minority phase, the ECPs lower the energy barriers for the nucleation of the MPDs/MPPs and cause a significant increase in the nucleation rate of the MPDs/MPPs and, thus,promote the formation of Pb–Al alloys with a well-dispersed or even nanoparticles dispersed microstructure. The ECPs parameters show an important influence on the microstructure formation of Pb–Al alloys. The refinement extent of the MPDs/MPPs increases with the increase in the peak current density. For a given peak current density, the refinement extent of the MPDs/MPPs increases with the increases in the pulse frequency and pulse width first, and then level off and become asymptotic.
基金supported by the Knowledge Innovation Program of the Chinese Academy of Sciences,the National Natural Science Foundation of China (No.50704032)the Liaoning Province Natural Science Foundation of China (No.20081009)
文摘The directional solidification has been carried out for the AI-413i-2,5Co （wt pct） alloys with different melt superheat temperatures. The microstructure characterization and the quantitative metallographic analysis have been performed. The results indicated that the Bi-rich sphere size and cellular spacing decrease with increasing melt superheat temperature. The interaction between the advancing solidification interface and the Bi-rich spheres with different sizes was analyzed. The effect of the melt superheat treatment on microstructure evolution was discussed for the immiscible alloys. The microstructure development in ternary Al-Bi-Co alloys directionally solidified with different melt superheat temperatures was clarified.
基金supported by the National Natural Science Foundation of China(Grant Nos.51774264,51574216 and 51374194)the Natural Science Foundation of Liaoning Province of China(Grant No.2015020172)
文摘In this work, a quaternary Ni-Cu-Nb-Ta system has been designed to obtain composite microstructure with sphericalcrystalline Cu-rich particles embedded in amorphous Ni-rich matrix. The alloy samples were prepared by using single-roller melting-spinning method. The microstructure and thermal properties of the as-quenched alloy samples were char-acterized by X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, anddifferential scanning calorimetry. It shows that the spherical crystalline Cu-rich particles are embedded in the amorphousNi-rich matrix. The average size of the Cu-rich particles is strongly dependent upon the Cu content. The effect of the alloycomposition on the behavior of liquid-liquid phase separation and microstructure evolution was discussed. The phaseformation in the Ni-based metallic glass matrix composite was analyzed.
文摘The solidified microstructure of immiscible alloys strongly depends on the nucleation, diffusional growth, especially the coalescence of the second phase droplets in the miscibility gap. A numerical model based on the discrete multi-particle approach was developed to simulate the nucleation and coalescence mode of the second phase droplets during the earth-based processing of immiscible alloys (in this case, the effect of gravity cannot be neglected). The cooling rate is the major factor influencing the coalescence mode. Under the super-rapid or rapid solidification condition (>104K/s), Brownian collision is the dominant coalescence mode. Marangoni collision becomes the dominant mode under the sub-rapid solidification condition (>102K/s). In the conventional slow cooling scope(101K/s), Stokes collision becomes the dominant coalescence mode, correspondingly, leading to a serious phase segregation.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.51771210,51471173 and 51501207)the China's Manned Space Station Project(Mission No.TGJZ800-2-RW024)the Natural Science Foundation of Liaoning Province(Grant No.201501043)
文摘Immiscible alloys have aroused considerable interests in the last decades on account of their special physical andmechanical properties and potential applications. A considerable number of researches have been implemented toinvestigate the solidification behaviors of immiscible alloys in electric and magnetic fields. It has been indicated that themagnetic field and electric current can remarkably affect the solidification process and microstructures of immisciblealloys. The solidification techniques under the effects of electric and magnetic fields have great potentials for the fabri-cation of immiscible alloys. This paper reviews the research work in this field in recent years.
文摘Immiscible alloys are attractive for their valuable physical and mechanical properties. In this paper, Al-ln immiscible alloy is prepared by melt spinning process and its morphological evolution is studied at various indium contents. The results show that the morphologies of the matrix phase depend on the indium content. Different morphologies lead to different distribution of the second phase particles. Due to a particular solidification mechanism of immiscible alloys, even under the melt spinning rapid solidification condition, it is still impossible to produce homogeneous Al-ln hypomonotectic alloy ribbons. But for Al-ln hypermonotectic alloys, there is almost no segregation of the second phase throughout the cross section of the ribbons.
文摘Immiscible alloys have attracted growing interest for their valuable physical and mechanical properties. However, their production is difficult because of metallurgical problems in which there is a serious tendency for gravity separation in the region of the miscibility gap. So far the study on the liquid separation mechanism is still one of the important projects in the spatial materials science and the spatial fluid science. The studied results about the liquid phase separating mechanism of immiscible alloys are presented, at the same time the preparation techniques of homogeneous immiscible alloys are summarized, and the existing problems and the related researching areas in the future are also pointed out.
基金financially supported by the National Natural Science Foundation of China(Nos.51027005,51271119 and51574165)Shanghai Science&Technology Committee(No.11JC1405900)
文摘Using synchrotron X-ray imaging technique,the segregation evolution in solidifying Al-10 wt% Bi immiscible alloys was investigated at different cooling rates.Irrespective of the cooling rate,most of the Bi solute appeared at the upper part of the sample after solidification.The reason for this Bi enrichment phenomenon is different for different cooling rates.Besides Marangoni motion,positive segregation,which has rarely been noticed before,can also make Bi solute transfer to the hot top zone.It is also found that,bubbles（or pores） appear in solidifying Al-10 wt% Bi alloys,and the number of bubbles（or pores） increases with the increase of the cooling rate,while the size of the bubbles（or pores） decreases.
