Please wait a minute...
Acta Metall Sin  2020, Vol. 56 Issue (2): 212-220    DOI: 10.11900/0412.1961.2019.00192
Current Issue | Archive | Adv Search |
Study on the Solidification of Ag-Ni Monotectic Alloy
DENG Congkun1,2,JIANG Hongxiang1,ZHAO Jiuzhou1(),HE Jie1,ZHAO Lei3
1. Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
2. University of Chinese Academy of Sciences, Beijing 100049, China
3. School of Mechanical Engineering, Liaoning Shihua University, Fushun 113001, China
Download:  HTML  PDF(8344KB) 
Export:  BibTeX | EndNote (RIS)      

The Ag-Ni alloy has high electrical conductivity, good thermal conductivity, high specific heat capacity, and excellent electrical wear resistance if the Ni-rich phase is dispersedly distributed in the Ag-based matrix. It has been widely used in the medium load contactors, magnetic starters, relays, etc. However, Ag-Ni alloy is a typical monotectic system. Generally, the liquid-liquid phase transformation leads to the formation of a solidification microstructure with serious phase segregation. So far, there have been few studies on the solidification process of Ag-Ni alloys and powder-metallurgical techniques are commonly used to prepare Ag-Ni alloys in industry. In this work, casting experiments and microhardness test were carried out with the Ag-Ni monotectic alloy. The samples with composite microstructure, in which the Ni-rich particles dispersed homogeneously in Ag matrix, were obtained. The microhardness of Ag-Ni alloy increases with the increase of nickel content and the cooling rate of the sample during solidification. When the cooling rate during the liquid-liquid phase transition of the Ag-4.0%Ni alloy reaches 1800 K/s, the microhardness of the Ag-4.0%Ni alloy is close to that of the Ag-10.0%Ni sheet electrical contacts produced by powder metallurgy. A model describing the microstructure evolution during cooling Ag-Ni monotectic alloy melt has been proposed. The process of microstructure formation has been simulated and discussed in details. The results indicate that the cooling rate during the nucleation of the Ni-rich droplets/particles has a dominant influence on the solidification microstructure. The average radius of the Ni-rich particles increases with the increase of nickel content, while it decreases with the increase of the cooling rate during solidification. The average radius of the Ni-rich particles shows an inverse square root dependence on the cooling rate during the nucleation of the Ni-rich droplets/particles. The Ostwald coarsening of the Ni-rich droplets/particles is very weak during cooling Ag-Ni monotectic alloy melt. Rapid/sub-rapid solidification has a good application prospect in the preparation of the high-performance Ag-Ni contact materials.

Key words:  Ag-Ni monotectic alloy      liquid-liquid phase separation      solidification microstructure      microhardness      simulation     
Received:  13 June 2019     
ZTFLH:  TG111.4  
Fund: National Natural Science Foundation of China(51771210);National Natural Science Foundation of China(51574216);National Natural Science Foundation of China(51774264);Basic Research Project of Education Department of Liaoning Province(L2017LQN022)
Corresponding Authors:  Jiuzhou ZHAO     E-mail:

Cite this article: 

DENG Congkun,JIANG Hongxiang,ZHAO Jiuzhou,HE Jie,ZHAO Lei. Study on the Solidification of Ag-Ni Monotectic Alloy. Acta Metall Sin, 2020, 56(2): 212-220.

URL:     OR

Fig.1  Experimental results (symbols) and calculated results (solid lines) of the cooling curves for the center region of Ag-4.0%Ni alloys with different diameters (d) (T—temperature, t—time, Tm and Te refer to the monotectic reaction temperature and the eutectic reaction temperature of Ag-Ni alloy, respectively)
Fig.2  Schematic distribution of the Ni-rich particles in Ag-4.0%Ni alloy with a diameter of 8 mm (a), measured volume fraction (φsβ) distributions of the Ni-rich particles along the axial z direction (b) and radial r direction (c)
Fig.3  SEM images of the Ag-xNi alloys for the samples of 5 mm in diameter with x=1.25% (a), x=2.24% (b), x=3.0% (c) and x=4.0% (d)
Fig.5  Average 2D radius (<R>2D) of the Ni-rich particles in Ag-Ni alloys for the samples of 5 mm in diameter vs alloy composition
Fig.6  SEM images showing solidification micro-structures of Ag-4.0%Ni alloys with diameters of 4 mm (a), 6 mm (b) and 8 mm (c)
Fig.7  Experimental results (black symbols) and calculated results (black line) of <R>2D of the Ni-rich particles in Ag-4.0%Ni alloys and the cooling rate of the melt during the nucleation (T.nuc, red line and symbols) of the Ni-rich droplets as a function of sample diameter
Fig.8  Microhardnesses of Ag-Ni alloys as a function of alloy composition for the samples of 5 mm in diameter (a) and as a function of sample diameter for the Ag-4.0%Ni alloys (b)
Thermal conductivity of liquid Ag klAg122.29093+0.04259TW·K-1·m-1
Thermal conductivity of liquid Ni klNi57W·K-1·m-1
Thermal conductivity of solid Ag ksAg429W·K-1·m-1
Thermal conductivity of solid Ni ksNi90.7W·K-1·m-1
Density of liquid Ag ρlAg9330-0.91(T-1233.7)kg·m-3
Density of liquid Ni ρlNi7905-1.19(T-1727)kg·m-3
Density of solid Ag ρsAg10500kg·m-3
Density of solid Ni ρsNi8900kg·m-3
Specific heat of liquid Ag cpl,Ag283J·kg-1·K-1
Specific heat of liquid Ni cpl,Ni620J·kg-1·K-1
Specific heat of solid Ag cps,Ag235J·kg-1·K-1
Specific heat of solid Ni cps,Ni444J·kg-1·K-1
Latent heat of solidification of pure Ag LAg102809J·kg-1
Latent heat of solidification of pure Ni LNi292334J·kg-1
Table 1  The thermophysical property parameters of Ag-Ni system[31,32]
Fig.9  Supersaturation (S, red line) of the matrix melt, nucleation rate (I, green line), number density (N, black line) and <R>2D (blue line) of the Ni-rich droplets/particles in the center region of the sample as a function of time during cooling the Ag-2.24%Ni alloy (solid line) and Ag-4.0%Ni alloy (dashed line) for the samples of 5 mm in diameter (a), and the enlargement of the microstructure evolution during the period from 55 ms to 265 ms (b)
Fig.10  Cooling rate (T., black line) and supersaturation (S, red line) of the matrix melt and nucleation rate (I, green line) of the Ni-rich droplets in the center region of the sample as a function of time during cooling a Ag-4.0%Ni alloy sample with a diameter of 4 mm (solid line) and 6 mm (dashed line)
Fig.11  Experimental results (solid circles) and calculated results (open circles) of the average radius (<R>) of the Ni-rich particles in Ag-xNi alloys with x=1.25% (blue color), x=2.24% (green color), x=3.0% (red color), x=4.0% (black color) vsT.nuc of the Ni-rich droplets/particles
[1] Li W S, Li Y M, Zhang J, et al. Progress in the research and application of silver-based electrical contact materials [J]. Mater. Rev., 2011, 25(6): 34
[1] (李文生, 李亚明, 张 杰等. 银基电接触材料的应用研究及制备工艺 [J]. 材料导报, 2011, 25(6): 34)
[2] Huang G L, Yan X F, Li G W, et al. Preparation and performance analysis of AgNi(10) electrical contact material by chemical co-deposition [J]. Electr. Eng. Mater., 2010, (1): 12
[2] (黄光临, 颜小芳, 李国伟等. 化学共沉积AgNi(10)电触点材料的制备及性能分析 [J]. 电工材料, 2010, (1): 12)
[3] Rajkumar V B, Chen S W. Thermodynamic modeling of Ag-Ni system combining experiments and molecular dynamic simulation [J]. J. Electron. Mater., 2017, 46: 2282
[4] Zhao J Z, Jiang H X. Progress in the solidification of monotectic alloys [J]. Acta Metall. Sin., 2018, 54: 682
[4] (赵九洲, 江鸿翔. 偏晶合金凝固过程研究进展 [J]. 金属学报, 2018, 54: 682)
[5] Wang S B, Xie M, Liu M M, et al. Research progress of AgNi contact materials [J]. Rare Met. Mater. Eng., 2013, 42: 875
[5] (王塞北, 谢 明, 刘满门等. AgNi电触头材料研究进展 [J]. 稀有金属材料与工程, 2013, 42: 875)
[6] Jiang D Z, Zhang J, Bai Y L, et al. Application performance and preparation technology of AgNi contact materials [J]. Electr. Eng. Mater., 2014, (3): 19
[6] (蒋德志, 章 杰, 白娅玲等. AgNi触头材料应用性能及其主要制备工艺 [J]. 电工材料, 2014, (3): 19)
[7] Qin G Y, Wang J H, Zhao H Z, et al. Rapid solidification texture of Ag-Ni and Ag-Fe powders by ultrasonic arc spray [J]. Chin. J. Nonferrous Met., 2009, 19: 286
[7] (秦国义, 王剑华, 赵怀志等. 超音速电弧喷雾Ag-Ni、Ag-Fe粉末的快速凝固组织特征 [J]. 中国有色金属学报, 2009, 19: 286)
[8] Liu N, Liu F, Chen Z, et al. Liquid-phase separation in rapid solidification of undercooled Fe-Co-Cu melts [J]. J. Mater. Sci. Technol., 2012, 28: 622
[9] Dai R R, Zhang S G, Guo X, et al. Formation of core-type microstructure in Al-Bi monotectic alloys [J]. Mater. Lett., 2011, 65: 322
[10] Huang Q, Luo X H, Li Y Y. An alloy solidification experiment conducted on Shenzhou spacecraft [J]. Adv. Space Res., 2005, 36: 86
[11] He J, Mattern N, Tan J, et al. A bridge from monotectic alloys to liquid-phase-separated bulk metallic glasses: Design, microstructure and phase evolution [J]. Acta Mater., 2013, 61: 2102
[12] Zhu D Y, Yang X H, Han X J, et al. Rapid solidification microstructures of Fe-Sn monotectic alloys at deep undercooling [J]. Chin. J. Nonferrous Met., 2003, 13: 328
[12] (朱定一, 杨晓华, 韩秀君等. Fe-Sn偏晶合金的深过冷快速凝固组织 [J]. 中国有色金属学报, 2003, 13: 328)
[13] Yan N, Wang W L, Dai F P, et al. Microstructure formation mechanism of rapidly solidified ternary Co-Cu-Pb monotectic alloys [J]. Acta Phys. Sin., 2011, 60: 36402
[13] (闫 娜, 王伟丽, 代富平等. 三元Co-Cu-Pb偏晶合金的快速凝固组织形成规律研究 [J]. 物理学报, 2011, 60: 36402)
[14] He J, Zhao J Z, Ratke L. Solidification microstructure and dynamics of metastable phase transformation in undercooled liquid Cu-Fe alloys [J]. Acta Mater., 2006, 54: 1749
[15] Silva A P, Spinelli J E, Garcia A. Thermal parameters and microstructure during transient directional solidification of a monotectic Al-Bi alloy [J]. J. Alloys Compd., 2009, 475: 347
[16] Wang J, Zhong Y B, Ren W L, et al. Effect of high static magnetic field and AC current on solidification of Zn-30wt%Bi monotectic alloy [J]. Acta Phys. Sin., 2009, 58: 893
[16] (王 江, 钟云波, 任维丽等. 强磁场复合交变电流作用下Zn-30wt%Bi偏晶合金的凝固 [J]. 物理学报, 2009, 58: 893)
[17] Jiang H X, Zhao J Z, Wang C P, et al. Effect of electric current pulses on solidification of immiscible alloys [J]. Mater. Lett., 2014, 132: 66
[18] Zhang L, Wang E G, Zuo X W, et al. Effect of high magnetic field on the transition behavior of Cu-rich particles in Cu-80%Pb hypermonotectic alloy [J]. Acta Metall. Sin., 2010, 46: 423
[18] (张 林, 王恩刚, 左小伟等. 强磁场对Cu-80%Pb过偏晶合金中富Cu颗粒迁移行为的影响 [J]. 金属学报, 2010, 46: 423)
[19] Sun Q, Jiang H X, Zhao J Z. Effect of micro-alloying element Bi on solidification and microstructure of Al-Pb alloy [J]. Acta Metall. Sin., 2016, 52: 497
[19] (孙 倩, 江鸿翔, 赵九洲. 微量元素Bi对Al-Pb合金凝固过程及显微组织的影响 [J]. 金属学报, 2016, 52: 497)
[20] Shi R P, Wang C P, Wheeler D, et al. Formation mechanisms of self-organized core/shell and core/shell/corona microstructures in liquid droplets of immiscible alloys [J]. Acta Mater., 2013, 61: 1229
[21] Wang C P, Liu X J, Shi R P, et al. Design and formation mechanism of self-organized core/shell structure composite powder in immiscible liquid system [J]. Appl. Phys. Lett., 2007, 91: 141904
[22] Li H L, Zhao J Z. Convective effect on the microstructure evolution during a liquid-liquid decomposition [J]. Appl. Phys. Lett., 2008, 92: 241902
[23] Guo J J, Liu Y, Jia J, et al. Coarsening mode and microstructure evolution of Al-In hypermonotectic alloy during rapidly cooling process [J]. Scr. Mater., 2001, 45: 1197
[24] Zhou F M, Sun D K, Zhu M F. Lattice Boltzmann modelling of liquid-liquid phase separation of monotectic alloys [J]. Acta Phys. Sin., 2010, 59: 3394
[24] (周丰茂, 孙东科, 朱鸣芳. 偏晶合金液-液相分离的格子玻尔兹曼方法模拟 [J]. 物理学报, 2010, 59: 3394)
[25] Zhao J Z, Ratke L, Jia J, et al. Modeling and simulation of the microstructure evolution during a cooling of immiscible alloys in the miscibility gap [J]. J. Mater. Sci. Technol., 2002, 18: 197
[26] Zhao J Z, Li H L, Zhang X F, et al. Microstructure evolution during a liquid-liquid decomposition under the common action of the nucleation, growth and Ostwald ripening of droplets [J]. Int. J. Mater. Res., 2009, 100: 46
[27] Lv L X, Zhen L, Xu C Y, et al. Phase field simulation of spinodal decomposition under external magnetic field [J]. J. Magn. Magn. Mater., 2010, 322: 978
[28] Jiang H X, Zhao J Z, He J. Solidification behavior of immiscible alloys under the effect of a direct current [J]. J. Mater. Sci. Technol., 2014, 30: 1027
[29] Ratke L, Diefenbach S. Liquid immiscible alloys [J]. Mater. Sci. Eng., 1995, R15: 263
[30] Patankar S V, translated by Zhang Z. Numerical Heat Transfer and Fluid Flow [M]. Beijing: Science Press, 1984: 27
[30] (Patankar S V著, 张 政译. 传热与流体流动的数值计算 [M]. 北京: 科学出版社, 1984: 27)
[31] Gale W F, Totemeier T C. Smithells Metals Reference Book [M]. 8th Ed., The Netherlands: Elsevier Butterworth-Heinemann, 2004: 1127
[32] Iida T, Guthrie R I L, translated by Xian A P, Wang L W. The Physical Properties of Liquid Metals [M]. Beijing: Science Press, 2006: 234
[32] (Iida T, Guthrie R I L著, 冼爱平, 王连文译. 液态金属的物理性能 [M]. 北京: 科学出版社, 2006: 234)
[33] Yang Z Z, Sun Q, Zhao J Z. Directional solidification of monotectic composition Al-Bi alloy [J]. Acta Metall. Sin., 2014, 50: 25
[33] (杨志增, 孙 倩, 赵九洲. Al-Bi偏晶点成分合金定向凝固过程研究 [J]. 金属学报, 2014, 50: 25)
[1] CHEN Yongjun, BAI Yan, DONG Chuang, XIE Zhiwen, YAN Feng, WU Di. Passivation Behavior on the Surface of Stainless Steel Reinforced by Quasicrystal-Abrasive via Finite Element Simulation[J]. 金属学报, 2020, 56(6): 909-918.
[2] WANG Xia, WANG Wei, YANG Guang, WANG Chao, REN Yuhang. Dimensional Effect on Thermo-Mechanical Evolution of Laser Depositing Thin-Walled Structure[J]. 金属学报, 2020, 56(5): 745-752.
[3] LIU Jizhao, HUANG Hefei, ZHU Zhenbo, LIU Awen, LI Yan. Numerical Simulation of Nanohardness in Hastelloy N Alloy After Xenon Ion Irradiation[J]. 金属学报, 2020, 56(5): 753-759.
[4] WANG Bo,SHEN Shiyi,RUAN Yanwei,CHENG Shuyong,PENG Wangjun,ZHANG Jieyu. Simulation of Gas-Liquid Two-Phase Flow in Metallurgical Process[J]. 金属学报, 2020, 56(4): 619-632.
[5] ZHOU Xia,LIU Xiaoxia. Mechanical Properties and Strengthening Mechanism of Graphene Nanoplatelets Reinforced Magnesium Matrix Composites[J]. 金属学报, 2020, 56(2): 240-248.
[6] ZHANG Jun,JIE Ziqi,HUANG Taiwen,YANG Wenchao,LIU Lin,FU Hengzhi. Research and Development of Equiaxed Grain Solidification and Forming Technology for Nickel-Based Cast Superalloys[J]. 金属学报, 2019, 55(9): 1145-1159.
[7] XU Qingyan,YANG Cong,YAN Xuewei,LIU Baicheng. Development of Numerical Simulation in Nickel-Based Superalloy Turbine Blade Directional Solidification[J]. 金属学报, 2019, 55(9): 1175-1184.
[8] Peiyuan DAI,Xing HU,Shijie LU,Yifeng WANG,Dean DENG. Influence of Size Factor on Calculation Accuracy of Welding Residual Stress of Stainless Steel Pipe by 2D Axisymmetric Model[J]. 金属学报, 2019, 55(8): 1058-1066.
[9] Wang LI,Qian SUN,Hongxiang JIANG,Jiuzhou ZHAO. Solidification of Al-Bi Alloy and Influence of Microalloying Element Sn[J]. 金属学报, 2019, 55(7): 831-839.
[10] Bin CHEN,Jie HE,Xiaojun SUN,Jiuzhou ZHAO,Hongxiang JIANG,Lili ZHANG,Hongri HAO. Liquid-Liquid Phase Separation of Fe-Cu-Pb Alloy and Its Application in Metal Separation and Recycling of Waste Printed Circuit Boards[J]. 金属学报, 2019, 55(6): 751-761.
[11] Baojun ZHAO,Yuhong ZHAO,Yuanyang SUN,Wenkui YANG,Hua HOU. Effect of Mn Composition on the Nanometer Cu-Rich Phase of Fe-Cu-Mn Alloy by Phase Field Method[J]. 金属学报, 2019, 55(5): 593-600.
[12] ZHANG Qingdong, LIN Xiao, LIU Jiyang, HU Shushan. Modelling of Q&P Steel Heat Treatment Process Based on Finite Element Method[J]. 金属学报, 2019, 55(12): 1569-1580.
[13] LU Shijie, WANG Hu, DAI Peiyuan, DENG Dean. Effect of Creep on Prediction Accuracy and Calculating Efficiency of Residual Stress in Post Weld Heat Treatment[J]. 金属学报, 2019, 55(12): 1581-1592.
[14] MA Kai, ZHANG Xingxing, WANG Dong, WANG Quanzhao, LIU Zhenyu, XIAO Bolv, MA Zongyi. Optimization and Simulation of Deformation Parameters of SiC/2009Al Composites[J]. 金属学报, 2019, 55(10): 1329-1337.
[15] Haifeng ZHANG, Haile YAN, Nan JIA, Jianfeng JIN, Xiang ZHAO. Exploring Plastic Deformation Mechanism of MultilayeredCu/Ti Composites by Using Molecular Dynamics Modeling[J]. 金属学报, 2018, 54(9): 1333-1342.
No Suggested Reading articles found!