V-Ti-Fe三元合金显微组织、氢传输行为及耐蚀性能研究

Study on Microstructure,Hydrogen Transportation Behavior and Corrosion Resistance of V-Ti-Fe Alloy

Nb-Ti-Fe双相合金已被证实具有优异的渗氢性能,有望成为替代传统Pd膜的渗氢材料。V和Nb同属于5B族,具有类似的物理化学性质,但是,V-Ti-Fe双相合金组织转变规律和渗氢性能至今无人研究。基于此,本工作对V-Ti-Fe三元合金的显微组织和渗氢行为开展了详细研究,并探索了热处理和电化学腐蚀对改善渗氢性能的可能性。研究结果表明:V-Ti-Fe三元合金体系中存在一个包共晶凝固反应,即L+TiFe_(2)→Bcc-(V,Ti)+TiFe(1626 K)。液相面投影图中存在三个相区,分别为TiFe相区、TiFe_(2)相区和Bcc-(V,Ti)相区。其中,TiFe相区合金室温组织由初生TiFe相和{Bcc-(V,Ti)+TiFe}共晶结构组成,TiFe_(2)相区合金室温组织由初生TiFe相、TiFe_(2)相和Bcc-(V,Ti)相构成,Bcc-(V,Ti)相区合金室温组织由初生Bcc-(V,Ti)相和TiFe相组成,渗氢性能测试证实了该系合金抗氢脆性能较弱。具体来说,上述三区域内部铸态合金在渗氢实验前均发生了不同程度的破碎,仅V_(2.5)Ti_(62.5)Fe_(35)合金能够渗氢,不过,该合金在渗氢后期发生断裂。最后,本工作采用电化学腐蚀和真空热处理两种方法改善该合金体系的渗氢性能,其中,V_(2.5)Ti_(62.5)Fe_(35)合金具有较高的耐腐蚀性能,经热处理后该合金的渗氢性能明显提升,其在623 K下的氢渗透性能为1.03×10^(-9)mol H_(2)m^(-1)·s^(-1)·Pa^(-0.5)。

Nb-Ti-Fe duplex alloys have been proven to have excellent hydrogen permeability,which are also expected to become a hydrogen permeable material to replace traditional Pd films.V and Nb belong to the same 5B group,with similar physical and chemical properties.However,the microstructure and hydrogen permeability changes of V-Ti-Fe have not been studied so far.Based on this,studying in detailed the microstructure and hydrogen transportation behavior of V-Ti-Fe ternary alloys,and the possibility of heat treatment and electrochemical corrosion for improving hydrogen permeability are explored.The results show that there is a quasiperitectic solidification reaction in the V-Ti-Fe ternary alloy system,determined as L+TiFe_(2)→V+TiFe(1626 K).There are three phase regions in the liquid phase projection surface,containing of the TiFe phase region,the TiFe_(2)phase region and the Bcc-(V,Ti)phase region.Among them,the room temperature structure of the TiFe phase alloy is composed of the primary TiFe phase and the{Bcc-(V,Ti)+TiFe}eutectic structure,the room temperature structure of the TiFe_(2)phase alloy is composed of the primary TiFe phase,TiFe_(2)phase and Bcc-(V,Ti)phase,and the room temperature structure of the Bcc-(V,Ti)phase alloy is composed of the primary Bcc-(V,Ti)phase and TiFe phase.Hydrogen permeability test confirmed that the alloy system has weak hydrogen embrittlement resistance.Specifically,the internal cast alloy in the above three regions has undergone different degrees of crushing during the hydrogen permeation experiment,and only the V 2.5 Ti 62.5 Fe 35 alloy can permeate hydrogen,but the alloy breaks during the hydrogen permeation process.Finally,the hydrogen permeability of the alloy system is improved by two methods,electrochemical corrosion and vacuum heat treatment.Of these alloys,V 2.5 Ti 62.5 Fe 35 alloy not only has high corrosion resistance,but also possesses excellent hydrogen permeability after heat treatment,and its hydrogen permeability is 1.03×10^(-9)mol H_(2)m^(-1)·s^(-1)·Pa-0.5 at 623 K.