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Core-shell microstructure formed in the ternary Fe-Co-Cu peritectic alloy droplet
FuPing Dai,BingBo Wei
Chinese Science Bulletin , 2009, DOI: 10.1007/s11434-009-0103-9
Abstract: The metastable liquid phase separation occurs in the ternary Cu50Fe37.5Co12.5 peritectic alloy droplets during free fall. The separated alloy melt rapidly solidifies and evolves core-shell microstructure composed of L1(Cu) and L2(Fe,Co) phases. Based on the determination of the phase transition temperature, the core-shell microstructure evolution, the interfacial energy, the temperature gradient and the Marangoni migration are analyzed. The interfacial energy of the separated liquid phase increases with the decrease of the temperature. The temperature gradient changes from large to small along the radius direction from inside to outside in the alloy droplet. The Marangoni force (F M) acting on the micro-droplet of L2(Fe,Co) phase increases with the increase of the size of the L2(Fe,Co) phase, and decreases with the increase of undercooling. Driven by F M, the micro-droplet of L2(Fe,Co) phase migrates from outside to inside in the alloy droplet, collides and coagulates each other during migration, and then forms different types of core-shell microstructures.
Solidification microstructure and phase constitution of Fe-7.5%Mo-16.5%Si ternary quasiperitectic alloy
Li Li,XiaoYu Lu,ChongDe Cao,FuPing Dai
Chinese Science Bulletin , 2010, DOI: 10.1007/s11434-009-3372-4
Abstract: Solidification of Fe-7.5%Mo-16.5%Si ternary quasiperitectic alloy is investigated by using differential scanning calorimetry (DSC) and drop tube containerless processing techniques. The primary phase is identified as R (Fe5Mo3Si2) and the quasiperitectic phases are τ1 (Fe5MoSi4) and Fe3Si. With the decrease of droplet diameter, the cooling rate and undercooling of the droplets increase rapidly. The experiment result indicates that the solidification microstructure is composed of remnant primary phase, quasiperitectic phases and ternary eutectic when the droplet diameter exceeds 400 μm, whereas the ternary eutectic is suppressed when the droplet is smaller than 400 μm in diameter.
Microstructure of Pd_(77.5)Au_6Si_(16.5) Alloy Droplet Solidified in a Drop Tube Process
Liling SUN,Qi WU,Liwei SUN,Wenkui WANG,

材料科学技术学报 , 1996,
Abstract: The microstructure development of Pd77.5Au6Si16.5 alloy droplet solidified in a drop tube process was studied. It was found that two distinct microstructures, i.e. (Pd,Au)3Si primary phase and Pd+(Pd,Au)3Si eutectic can be obtained when the droplet diameter is within the range between 2.3~0.4 mm. The morpologies of the (Pd,Au)3Si developed from dendrite trunk-like with single branching only into dendrite cluster-like with ternary branching with the decrease of the droplet diameter. When the droplet diameter is about 0.25 mm, the primary phase (Pd,Au)3Si almost disappears and the microstructure mainly shows Pd+(Pd,Au)3Si eutectic. The morphology of the eutectic transforms from fiber-like to plate-like with the decrease of the droplet diameter in the range between 2.3-0.25 mm. When the droplet diameter is about 0.19 mm, the microstructure is only the single phase of Pd solid solution
Microstructure and Peritectic Reaction within As-solidified Mg-Zn-Y Alloy
Microstructure and Peritectic Reaction within As-solidified Mg–Zn–Y Alloy

Diqing WAN,Gencang YANG,

材料科学技术学报 , 2008,
Abstract: An investigation on the microstructure and peritectic reaction involving icosahedra phase (I-phase) and crystalline phase (W-phase) within Mg-Zn-Y alloy during conventional solidification technology and rapid quench- ing was carried out. The solidification process of the peritectic reaction is discussed in details. It is shown that there is no obvious crystallographic relationship between the W-phase and I-phase during the solidification of Mg-Zn-Y alloy.

LI Xinzhong,SU Yanqing,GUO Jingjie,WU Shiping,FU Hengzhi,

金属学报 , 2006,
Abstract: A phase-field model was built by optimizing characteristic parameters in the convectional phase-field model for peritectic transition, which is suitable to simulate microstructure evolution for peritectic transition of specific alloys. The growth of peritectic phase along the primary phase surface was simulated using this model for directionally solidified Ti-Al alloy at a high value of G/Vp. The simulating results show that the difference of extending character of trijunction will cause two typical microstructures of discrete band and island band. Furthermore, the width of computational domain, the nucleation undercooling of peritectic phase and initial composition affect the extension of trijunction of directionally solidified peritectic alloy directly, and also the final microstructure.
Formation mechanism of layered microstructure and monotectic cell within rapidly solidified Fe62.1Sn27.9Si10 alloy

Li Zhi-Qiang,Wang Wei-Li,Zhai Wei,Wei Bing-Bo,

物理学报 , 2011,
Abstract: Ternary Fe62.1Sn27.9Si10 monotectic alloy is rapidly solidified in drop tube with the freely-falling-body techniqual and with melt spinning method separately.The phase separation,the microstructure characteristics,and the heat transfer of this alloy are investigated theoretically.Under free fall condition,the core-shell structure with two layers is formed because of Marangoni migration and surface segregation,where the Sn-rich phase is always located at droplet surface and the Fe-rich phase in the center.Wi...

SU Yanqing,LI Xinzhong,GUO Jingjie,WU Shiping,FU Hengzhi,

金属学报 , 2006,
Abstract: The microstructure evolution of both phases is simulated by the phase-field model of peritectic transition for directionally solidified Ti-Al alloy at a high value of Give when the continuous nucleation occured to a sample with a small diameter and the multiple nucleation occured to a sample with a big diameter. The simulated results show that for the small sample decreasing sample size or nucleation undercooling of peritectic phase tended to form island band structure. But to the big sample, the differences of the volume fraction of peritectic phase and the nucleation rate cause to form the discrete band, island band and coupled-growth structures.
Rapid solidification mechanism of Ag60Sb34Cu6 ternary alloy in drop tube
Ying Ruan,Nan Wang,Chongde Cao,Bingbo Wei
Chinese Science Bulletin , 2004, DOI: 10.1007/BF03183403
Abstract: Droplets of Ag60Sb34Cu6 ternary alloy within the diameter range of 60–800 μm were rapidly solidified by means of drop tube containerless processing, and the solidification mechanism is analyzed. With a decrease in droplet size, the cooling rate increases from 57 to 5.8×104 K/s. The maximum undercooling is determined to be 180 K (0.23T L) and the microstructure of primary ε(Ag3Sb) dendrite refines drastically until homogenous equiaxed dendrite forms. Experimental results indicate that (ε+Ag) pseudobinary eutectic cannot form under high undercooling conditions and the solubility of Ag in primary ε phase increases as undercooling increases. Based on thermal analysis and crystal growth morphology, it is found that this alloy is solidified in two ways corresponding to different undercooling levels.
Contribution to the Study of the Relation between Microstructure and Electrochemical Behavior of Iron-Based FeCoC Ternary Alloys
Farida Benhalla-Haddad,Sif Eddine Amara,Abdelkader Benchettara,Kamel Taibi,Rafika Kesri
Journal of Analytical Methods in Chemistry , 2012, DOI: 10.1155/2012/798043
Abstract: This work deals with the relation between microstructure and electrochemical behavior of four iron-based FeCoC ternary alloys. First, the arc-melted studied alloys were characterized using differential thermal analyses and scanning electron microscopy. The established solidification sequences of these alloys show the presence of two primary crystallization phases (δ(Fe) and graphite) as well as two univariante lines : peritectic L
Microstructure evolution and heterogeneous nucleation in ternary Al-Cu-Ni alloys  [PDF]
J. Kundin,E. Pogorelov,H. Emmerich
Physics , 2013,
Abstract: The simulations of the solidification of ternary Al-Cu-Ni alloys by means of a general multi-phase-field model for an arbitrary number of phases reveal that the real microstructure can be generated by coupling the real thermodynamic parameters of the phases and the evolution equations. The stability requirements on individual interfaces for model functions guarantee an absence of "ghost" phases in a $n$-dimensional phase-field space. The special constructed thermal noise terms disturb the stability and can produce the heterogeneous nucleation of product phases in accordance to the energetic and concentration conditions. Of particular interest is that in triple points the nucleation of the forth phase occurs without additional noise. Another observation is the growth of the eutectic-like or peritectic-like structure in various alloys.
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