Mechanism of intermediate temperature embrittlement in Ni( Bi) alloy
Tensile ductility of Ni( Bi) alloy and high purity Ni are tested at room temperature and elevated temperatures in the range of 400℃ to 850℃ after various thermal pre-treatments.Room-temperature tensile ductility of Ni( Bi) alloy reveals clear minimum after a critical time of isothermal pre-annealing at 750℃ or 650℃.Elevated-temperature tensile ductility of the alloy shows evident intermediate temperature embrittlement with minimum ductility between 700℃ and 750℃,while that of high purity Ni does not.Fractography demonstrates intergranular fracture for samples of low ductility.Furthermore,atom probe analysis indicates a strong tendency of Bi segregation to grain boundaries in nanocrystalline Ni-3at% Bi layer.Based on these observations,non-equilibrium grain-boundary segregation of Bi is identified to control intermediate temperature embrittlement in Ni(Bi) alloy.
nickel alloy grain boundary segregation atom probe tomography tensile test embrittlement
ZHENG Lei MENG Ye YANG Wuqiang XU Min
School of Materials Science and Engineering,University of Science and Technology Beijing,Beijing 100083,China
国内会议
上海
英文
1-8
2013-06-01（万方平台首次上网日期，不代表论文的发表时间）