The Experts below are selected from a list of 222 Experts worldwide ranked by ideXlab platform

Peng Peng - One of the best experts on this subject based on the ideXlab platform.

  • Determination of the Liquid diffusion coefficient of the Sn-Ni peritectic alloy through temperature gradient Zone melting
    International Journal of Heat and Mass Transfer, 2020
    Co-Authors: Peng Peng, Jinmian Yue, Anqiao Zhang
    Abstract:

    Abstract In the present work, a new method determining the Liquid phase diffusion coefficients DL in a binary peritectic alloy is presented. This method is based on the evolution in both the microstructure and melt concentrations which can be linked through Liquid droplet migration in the mushy Zone during thermal stabilization. The thermal stabilization experiments of different time (2 to 8 h) are performed on Sn–Ni peritectic alloy (L+Ni3Sn2→Ni3Sn4) in a Bridgman-type directional solidification furnace. Two different mushy Zones are formed during thermal stabilization of samples which are kept still in the furnace. The diffusion-controlled Liquid droplet migration is caused by remelting/resolidification by temperature gradient Zone melting (TGZM). It leads to not only the variation of volume fractions of solid(fS)/Liquid(fL) phases in the mushy Zone but also the increase of the melt concentration in the complete-Liquid Zone C. Thus, based on the conservation of mass during thermal stabilization, fS and fL can be correlated to not only the Liquid droplet migration velocity vm but also the melt concentration in the complete-Liquid Zone C during thermal stabilization. Since fS and fL can be easily obtained through microstructure analysis, the experimental value of vm at specific location/temperature is given. Then, the expression of vm which is function of DL is provided by an analytical model describing the remelting/resolidification process during the Liquid migration. Finally, DL and the activation energy of the Sn-Ni peritectic alloy are obtained by equating the experimental values of vm with the expression of vm by this analytical model.

  • Morphology evolution of the interface between different mushy Zones of a Sn-Ni peritectic alloy in a temperature gradient
    Materials Letters, 2016
    Co-Authors: Peng Peng
    Abstract:

    Abstract During thermal stabilization, the (Ni 3 Sn 2 +Liquid) and (Ni 3 Sn 4 +Liquid) mushy Zones were formed between the complete Liquid Zone and the non-molten Zone due to the imposed temperature gradient. The morphology of the interface between these mushy Zones changed during thermal stabilization. A thin Liquid film which gradually disappeared was formed between the mushy Zones at the initial of thermal stabilization. Due to the solute diffusion through the Liquid channels by temperature gradient Zone melting (TGZM), the triple junctions at T P gradually moved upwards, leading to serrated interface. If the thermal stabilization time is long enough, this interface is smoothed.

  • Influence of solutal convection on solute distribution of melt during preparation of directionally solidified Sn–36 at.%Ni peritectic alloy
    International Journal of Heat and Mass Transfer, 2015
    Co-Authors: Peng Peng, Jingjie Guo
    Abstract:

    Abstract Experiments consisting of melting followed by thermal stabilization on Sn–36 at.%Ni peritectic alloy have been carried out in a Bridgman-type furnace. Due to imposed temperature gradient, a mushy Zone is created between the complete Liquid Zone and the non-molten Zone. Microstructure evolution and solute distribution in the melt during thermal stabilization have been characterized. As thermal stabilization time increases, the volume fraction of Liquid in the mushy Zone decreases. A Sn boundary layer which results from evacuation of Liquid in the mushy Zone is built up at the solid/Liquid interface at the initial of thermal stabilization then gradually disappears. A model is proposed to describe this boundary layer which is influenced by solutal convection during thermal stabilization. It is found that solute segregation in the complete Liquid Zone can be destroyed by solutal convection. This solute boundary layer can lead to further downward migration of the solid/Liquid interface during thermal stabilization.

Tzuoo-lun Yeh - One of the best experts on this subject based on the ideXlab platform.

  • The optimal variation of Zone lengths in multipass Zone refining processes
    Separation and Purification Technology, 1999
    Co-Authors: Ho-ming Yeh, Tzuoo-lun Yeh
    Abstract:

    The effect of variable Zone length on the separation efficiency in Zone refining processes was investigated theoretically. During Zone refining operation, properly adjusting the Zone length along the ingot influences the solute concentration in the Liquid Zone, leading to an enhancement of the extent of separation. For multipass operations, considerable improvement in separation is obtained by adjusting Zone lengths in each pass separately.

Jingjie Guo - One of the best experts on this subject based on the ideXlab platform.

  • Influence of thermal stabilization treatment on microstructure evolution of the mushy Zone and subsequent directional solidification in Ti-43Al-3Si alloy
    Materials & Design, 2016
    Co-Authors: Tong Liu, Liangshun Luo, Liang Wang, N.n. Guo, Ruirun Chen, Jingjie Guo
    Abstract:

    Abstract Thermal stabilization (TS) and directional solidification (DS) experiments were performed on Ti-43Al-3Si alloy in a Bridgman-type furnace. The effects of thermal stabilization time on the microstructure evolution of mushy Zone and initial interface of directional solidification were investigated. The results show that the volume fraction of Liquid in mushy Zone and the length of mushy Zone decrease as the thermal stabilization time increases. The concentrations of Al and Si exhibit a decreasing trend in the complete Liquid Zone with increasing TS time, while the solute concentrations of Al and Si in complete Liquid Zone are always higher than those of the original as-cast alloy. A long TS time promotes solute diffusion and provides a solute homogeneous initial interface for subsequent DS process. Isolated α grains and Ti 5 Si 3 particles in mushy Zone tend to coarsen with the increase of thermal stabilization time. Long time TS treatment also leads to growth of Ti 5 Si 3 particles which may act as nucleation sites to terminate the continuous growth of dendrite and inheritance of the lamellar orientation. Directionally solidified samples with aligned lamellar structures can be obtained within 30 min TS treatment in Ti-43Al-3Si alloy.

  • Influence of solutal convection on solute distribution of melt during preparation of directionally solidified Sn–36 at.%Ni peritectic alloy
    International Journal of Heat and Mass Transfer, 2015
    Co-Authors: Peng Peng, Jingjie Guo
    Abstract:

    Abstract Experiments consisting of melting followed by thermal stabilization on Sn–36 at.%Ni peritectic alloy have been carried out in a Bridgman-type furnace. Due to imposed temperature gradient, a mushy Zone is created between the complete Liquid Zone and the non-molten Zone. Microstructure evolution and solute distribution in the melt during thermal stabilization have been characterized. As thermal stabilization time increases, the volume fraction of Liquid in the mushy Zone decreases. A Sn boundary layer which results from evacuation of Liquid in the mushy Zone is built up at the solid/Liquid interface at the initial of thermal stabilization then gradually disappears. A model is proposed to describe this boundary layer which is influenced by solutal convection during thermal stabilization. It is found that solute segregation in the complete Liquid Zone can be destroyed by solutal convection. This solute boundary layer can lead to further downward migration of the solid/Liquid interface during thermal stabilization.

Ho-ming Yeh - One of the best experts on this subject based on the ideXlab platform.

  • The optimal variation of Zone lengths in multipass Zone refining processes
    Separation and Purification Technology, 1999
    Co-Authors: Ho-ming Yeh, Tzuoo-lun Yeh
    Abstract:

    The effect of variable Zone length on the separation efficiency in Zone refining processes was investigated theoretically. During Zone refining operation, properly adjusting the Zone length along the ingot influences the solute concentration in the Liquid Zone, leading to an enhancement of the extent of separation. For multipass operations, considerable improvement in separation is obtained by adjusting Zone lengths in each pass separately.

A.l. Greer - One of the best experts on this subject based on the ideXlab platform.

  • Shear bands in metallic glasses: Size effects on thermal profiles
    Acta Materialia, 2011
    Co-Authors: Daniel B. Miracle, A. Concustell, Yanhui Zhang, Alain Reza Yavari, A.l. Greer
    Abstract:

    Abstract The characteristic dimensions of the hot, Liquid Zone behind a moving shear-band front in a metallic glass are analyzed. In addition to the expected dependence on material constants, the thickness of the Zone is proportional to the shear offset, while its width is proportional to the square of the offset. Considering the bending of a plate, the size and shape of the hot Zone are found to be strongly dependent on plate thickness. For shear offsets ≪ 1 μ m , typical of plate thickness ≪ 100 μ m , local temperature rises are insignificant. For larger dimensions, local temperature rises give a Liquid Zone centered on the shear plane with width comparable to the sample dimensions. The scaling of characteristic lengths and times with plate thickness facilitates the interpretation of the transitions observed in mechanical behavior, and the variation in behavior from glass to glass.

  • Shear bands in metallic glasses: Size effects on thermal profiles
    Acta Materialia, 2011
    Co-Authors: Daniel B. Miracle, A. Concustell, Yanhui Zhang, Alain Reza Yavari, A.l. Greer
    Abstract:

    The characteristic dimensions of the hot, Liquid Zone behind a moving shear-band front in a metallic glass are analyzed. In addition to the expected dependence on material constants, the thickness of the Zone is proportional to the shear offset, while its width is proportional to the square of the offset. Considering the bending of a plate, the size and shape of the hot Zone are found to be strongly dependent on plate thickness. For shear offsets