Microstructure and Hardness of Ni-xSi Alloys

doi:10.1007/s12204-012-1339-0

Abstract

Abstract: 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.

Key words: Ni-Si alloy| intermetallic compound| microstructure| hardness

摘要： 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.

关键词: Ni-Si alloy| intermetallic compound| microstructure| hardness

CLC Number:

TG 146

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.

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