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探寻了Nb-Ti-Co氢分离合金的共晶点成分并利用Bridgman定向凝固实验对其进行验证,研究了近共晶点处9种合金的显微组织、氢渗透性能及氢脆现象,并与贵金属Pd的氢渗透性能进行比较.结果表明,Nb-Ti-Co三元合金中完全由共晶Nb[Ti,Co)+TiCo相构成的合金成分为Nb_(31)Ti_(35)Co_(34);当Bridgman定向凝固实验的抽拉速率为5μm/s时,共晶组织中的2相呈现岀规则的共生生长.9种合金中完全由共晶相构成的合金在673.5 K具有最大的氢渗透系数2.7×10~(-8)mol/(m·s·Pa~(0.5)),是相同条件下Pd的氢渗透系数的1.72倍;Nb含量相同时,随着Ti/Co比值的降低,氢渗透系数逐渐减小.氢渗透过程中,合金膜内部的初生TiCo相作为裂纹源首先萌生裂纹,而后以此发生二次裂纹现象并逐渐向膜边缘扩展;当TiCo相体积分数小于5%时,共晶Nb(Ti,Co)+TiCo相抵消原有初生TiCo相上的裂纹源,使得合金膜具有良好的抗氢脆性能.
The eutectic composition of Nb-Ti-Co hydrogen separation alloy was explored and verified by Bridgman directional solidification experiment. The microstructure, hydrogen permeability and hydrogen embrittlement of 9 alloys near the eutectic point were investigated. The results show that the composition of the Nb-Ti-Co ternary alloy consisting of Nb [Ti, Co] + TiCo phases is Nb 31 Ti 35 Co 4 34). When the draw rate of Bridgman directional solidification experiment is 5μm / s, the two phases in the eutectic structure exhibit symbiotic growth. The alloys composed entirely of eutectic phases in 9 kinds of alloys have the largest The hydrogen permeability coefficient is 2.7 × 10 -8 mol / (m · s · Pa ~ (0.5)), which is 1.72 times of the hydrogen permeability coefficient of Pd under the same conditions. With the same Nb content, with the Ti / Co ratio And the hydrogen permeability coefficient decreases gradually. During the hydrogen infiltration process, the primary TiCo phase in the alloy film first cracks as a crack source, and then the secondary cracks occur and gradually extend to the film edge. When the volume fraction of TiCo phase is less than 5 %, The eutectic Nb (Ti, Co) + TiCo phase counteracts the original crack source on the TiCo phase, which makes the alloy film have good resistance to hydrogen embrittlement.