The microstructure and hardness of conventionally solidified Ni-xSi (x = 21.4%, 22%, 24%, 26%) alloys
were investigated. The solidification microstructures of different Ni-Si alloys were observed by optical microscope
(OM) and scanning electron microscope (SEM) and the phase composition was indentified under the help of energy
dispersive X-ray (EDX) analysis. The macro- and micro-hardness of the Ni-Si alloys at room temperature were
also examined. The experimental results indicated that both the microstructure and hardness closely depended
on the Si content. Due to the vast formation of primary γ-Ni31Si12 phase, the hardness of Ni-26.0%Si alloy was
significantly improved compared with that of Ni-21.4%Si eutectic alloy. However, the fracture toughness was
greatly weakened simultaneously. The (β1-Ni3Si+γ-Ni31Si12) lamellar eutectoid structure formed in the primary
γ-Ni31Si12 phase exhibited better ductility than single γ-Ni31Si12 phase at the cost of relatively small hardness
reduction.
LIU Li1,2* (刘礼), MA Xiao-li1 (马晓丽), ZHAO Su3 (赵素)
. Microstructure and Hardness of Ni-xSi Alloys[J]. Journal of Shanghai Jiaotong University(Science), 2012
, 17(6)
: 648
-652
.
DOI: 10.1007/s12204-012-1339-0
[1] Li D Q, Lin D L, Liu Y. Deformation behavior of FeAl intermetallic alloy at elevated temperatures [J].Transactions of Nonferrous Metals Society of China,1998, 8(2): 235-239.
[2] Zhao Y H, Zhou J E, Yan W. Aluminum matrix composite reinforced by in-situ formed intermetallic Al3Ti [J]. Transactions of Nonferrous Metals Society of China, 2002, 12(4): 643-648.
[3] Mahajan S, Pande C S, Imam M A. Formation of annealing twins in f.c.c. crystals [J]. Acta Materialia,1997, 45(6): 2633-2638.
[4] Cui C J, Zhang J, Wu G N, et al. The preferential orientation of the directionally solidified Si-TaSi2 eutectic in situ composite [J]. Journal of Crystal Growth,2007, 309(1): 93-96.
[5] Gali A, Bei H, George E P. Thermal stability of Cr-Cr3Si eutectic microstructures [J]. Acta Materialia,2009, 57(13): 3823-3829.
[6] Kashyap S, Tiwary C S, Chattopadhyay K. Effect of Gallium on microstructure and mechanical properties of Nb-Si eutectic alloy [J]. Intermetallics, 2011,19(12): 1943-1952.
[7] Zhu J H, Liu C T. Intermediate-temperature mechanical properties of Ni-Si alloys: Oxygen embrittlement and its remedies [J]. Intermetallics, 2002, 10(4): 309-316.
[8] Lu Y P, Liu N, Shi T, et al. Microstructure and hardness of undercooled Ni78.6Si21.4 eutectic alloy [J]. Journal of Alloys Compounds, 2010, 490(1-2): L1-L4.
[9] Mukhtaroy S K, Valitov V A, Dudova N R. Thermal stability and mechanical properties of nanostructured nickel based alloy Inconel 718 [J]. Reviews on Advanced Materials Science, 2010, 25: 219-224.
[10] Fan K, Liu F, Yang G C, et al. Precipitation in assolidified undercooled Ni-Si hypoeutectic alloy: Effect of non-equilibrium solidification [J]. Materials Science and Engineering A, 2011, 528(22-23): 6844-6854.
[11] Karak¨ose E, Keskin M. Microstructure evolution and mechanical properties of intermetallic Ni-xSi(x = 5, 10, 15, 20) alloys [J]. Journal of Alloys and Compounds, 2012, 528: 63-69.
[12] Nash P, Nash A. Binary alloy phase diagram [M].Metals Park, OH, USA: ASM International, 1996:2859.
[13] Dutra A T, Ferrandini P L, Caram R. Microstructure and mechanical behavior of in situ Ni-Ni3Si composite [J]. Journal of Alloys Compounds,2007, 432(1-2): 167-171.
[14] Caram R, Milenkovic S. Microstructure of Ni-Ni3Si eutectic alloy produced by directional solidification [J].Journal of Crystal Growth, 1999, 198-199: 844-849.
