The two-stage gas boriding in N_(2)−H_(2)−BCl_(3)atmosphere was applied to producing a two-zoned borided layer on Nisil-alloy.The process was carried out at 910℃ for 2 h.The microstructure consisted of two zones diff...The two-stage gas boriding in N_(2)−H_(2)−BCl_(3)atmosphere was applied to producing a two-zoned borided layer on Nisil-alloy.The process was carried out at 910℃ for 2 h.The microstructure consisted of two zones differing in their phase composition.The outer layer contained only a mixture of nickel borides(Ni_(2)B,Ni_(3)B)only.The inner zone contained additionally nickel silicides(Ni_(2)Si,Ni_(3)Si)occurring together with nickel borides.The aim of this study was to determine the presence of nickel silicides on the mechanical properties of the borided layer produced on Ni-based alloy.The hardness and elastic modulus were measured using the nanoindenter with a Berkovich diamond tip under a load of 50 mN.The average values of indentation hardness(HI)and indentation elastic modulus(E_(I))obtained in the outer zone were respectively(16.32±1.03)GPa and(232±16.15)GPa.The presence of nickel silicides in the inner zone reduced the indentation hardness(6.8−12.54 GPa)and elastic modulus(111.79−153.99 GPa).The fracture toughness of the boride layers was investigated using a Vickers microindentation under a load of 0.981 N.It was confirmed that the presence of nickel silicides caused an increase in brittleness(by about 40%)of the gas-borided layer.展开更多
基金This work has been financially supported by Ministry of Science and Higher Education in Poland as a part of the Project No.0513/SBAD.
文摘The two-stage gas boriding in N_(2)−H_(2)−BCl_(3)atmosphere was applied to producing a two-zoned borided layer on Nisil-alloy.The process was carried out at 910℃ for 2 h.The microstructure consisted of two zones differing in their phase composition.The outer layer contained only a mixture of nickel borides(Ni_(2)B,Ni_(3)B)only.The inner zone contained additionally nickel silicides(Ni_(2)Si,Ni_(3)Si)occurring together with nickel borides.The aim of this study was to determine the presence of nickel silicides on the mechanical properties of the borided layer produced on Ni-based alloy.The hardness and elastic modulus were measured using the nanoindenter with a Berkovich diamond tip under a load of 50 mN.The average values of indentation hardness(HI)and indentation elastic modulus(E_(I))obtained in the outer zone were respectively(16.32±1.03)GPa and(232±16.15)GPa.The presence of nickel silicides in the inner zone reduced the indentation hardness(6.8−12.54 GPa)and elastic modulus(111.79−153.99 GPa).The fracture toughness of the boride layers was investigated using a Vickers microindentation under a load of 0.981 N.It was confirmed that the presence of nickel silicides caused an increase in brittleness(by about 40%)of the gas-borided layer.
