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 v-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 （31-Ni3Si＋7-Ni31Si12） lamellar eutectoid structure formed in the primary 7-Ni3zSi12 phase exhibited better ductility than single y-Ni31Sil2 phase at the cost of relatively small hardness reduction.
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 primaryγ-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 primaryγ-Ni31Si12 phase exhibited better ductility than singleγ-Ni31Si12 phase at the cost of relatively small hardness reduction.
基金
the Post-Doctoral Science Foundation of China(No.2011M500074)
the National Basic Research Program(973) of China(No.2011CB610405)
