Study Of Hydrogen Separation V-Ti-M(M=Cr、Mo、Y、Cu) Ternary Alloy Microstructure And Properties

Vanadium based alloy membranes have higher hydrogen permeability and lower cost than Pd alloy membranes,and they are potentially promising in the field of hydrogen separation alloy membrane purification.Compared with binary alloys such as V-Fe,V-Al and V-Cr,V-Ti alloy membranes have excellent cold roll forming ability and can maintain single-phase solid solution structure,which is chosen as a reference alloy.Therefore,in this paper,eight V-Ti-M ternary hydrogen separation alloys with different composition contents are designed based on V₉₀Ti₁₀ alloy with the addition of third group elements M=Cr,Mo,Y and Cu.The effects of the types and contents of hydrogen repelling elements on the organization and properties of V-Ti-M alloy were investigated by microstructure analysis,cold rolling and microhardness testing,hydrogen penetration test,hydrogen embrittlement resistance test and PCT hydrogen absorption test,and the results obtained from them are stated as follows.（1）The results showed that after adding Cr,Mo,Y and Cu to V₉₀Ti₁₀alloy,V_90-xTi₁₀Cr_xand V_90-xTi₁₀Mo_x（x=5,10,20）alloys maintained single-phase V-based solid solution structure,while V₈₅Ti₁₀Cu₅ and V₈₅Ti₁₀Y₅ had second-phase precipitation.After adding 5%of the third component,the cold roll forming ability of the V-Ti-M alloy was slightly reduced compared with that of the V₉₀Ti₁₀ alloy,but its deformation along the thickness direction could remain above 85%.After further increasing the Cr and Mo contents for the single-phase structured V_90-xTi₁₀Cr_x and V_90-xTi₁₀Mo_x alloys,the cold roll-forming ability of the alloys decreased rapidly,while the Vickers hardness gradually increased.For the V₈₅Ti₁₀Cu₅and V₈₅Ti₁₀Y₅ alloys with dual-phase organization,the cold-rolled elongation in the length direction was 510%and 622%,respectively,while the hardness of the former（HV=184.6）was higher than that of the latter（HV=124.9）,indicating that the strengthening effect of the second phase Ti Cu₂ particles was more obvious.（2）The J·L values of V₈₅Ti₁₀M₅ ternary alloy membranes at 400°C or 300°C under0.6 MPa were in the order of V₈₅Ti₁₀Cr₅>V₈₅Ti₁₀Cu₅>V₈₅Ti₁₀Y₅ from largest to smallest.where the J·L value of V₈₅Ti₁₀Cr₅ at 400°C was the largest at 87.6×10^-6mol H₂m^-1s^-1.The permeability of V₈₅Ti₁₀M₅ alloy at 673 K(Φ/10^-6mol H₂m^-1s^-1Pa^0.5)was 0.22,0.192,0.174,and 0.139 according to V₈₅Ti₁₀Mo₅,V₈₅Ti₁₀Cr₅,V₈₅Ti₁₀Cu₅,and V₈₅Ti₁₀Y₅ in order,all of which were much higher than that of pure Pd（0.016）at the same conditions.With the increase of Cr content and Mo content,the hydrogen flux and hydrogen permeability of both V_90-xTi₁₀Cr_xand V_90-xTi₁₀Mo_x gradually decreased,but the hydrogen flux and hydrogen permeability of V_90-xTi₁₀Mo_x were always higher than those of V_90-xTi₁₀Cr_x alloy membranes under the same conditions,which showed that the hydrogen repulsion effect of adding Cr element to V₉₀Ti₁₀alloy was stronger than that of Mo element.（3）The solubility coefficients(mol H₂m^-3Pa^-0.5)of A group V₈₅Ti₁₀Y₅,V₈₅Ti₁₀Cu₅,V₈₅Ti₁₀Mo₅ and V₈₅Ti₁₀Cr₅ at 673 K and 0.6 MPa were 14.31,18.28,19.13 and 19.27,respectively.At 573 K at 0.6 MPa,the The solubility coefficients of V₈₅Ti₁₀Y₅,V₈₅Ti₁₀Cu₅,V₈₅Ti₁₀Mo₅ and V₈₅Ti₁₀Cr₅ were 16.23,19.97,20.74 and 20.81,respectively.Comparing the hydrogen diffusion coefficients of A group,the diffusion coefficient of V₈₅Ti₁₀Mo₅ is the largest at 673 K,but at the same time its（r_u+r_d）/2 is also larger,which indicates that the hydrogen absorption is relatively larger in A group.At 673 K,the hydrogen diffusion coefficients of A group decreased in the order of V₈₅Ti₁₀Mo₅,V₈₅Ti₁₀Cr₅,V₈₅Ti₁₀Cu₅ and V₈₅Ti₁₀Y₅.The hydrogen dissolution in V_90-xTi₁₀Cr_x alloy gradually decreases with the increase of Cr content,and the solubility coefficient also decreases gradually.The solubility coefficient decreases from 19.27 to 13.61 after increasing the Cr content from 5%to 20%at673 K,and the hydrogen diffusion coefficient also decreases by about 43.5%.（4）Among the eight V-Ti-M alloy films studied,V₈₅Ti₁₀Cu₅,V₈₅Ti₁₀Y₅ and V₇₀Ti₁₀Cr₂₀ showed better hydrogen embrittlement resistance.The other five V-Ti-M alloys all experienced hydrogen embrittlement during the slow cooling process at 0.6 MPa pressure difference.The anti-hydrogen embrittlement performance of the alloy membranes of V₈₅Ti₁₀Cr₅ and V₈₅Ti₁₀Mo₅,which showed poor anti-hydrogen embrittlement ability,gradually improved when the Cr and Mo contents were further increased,with V₇₀Ti₁₀Cr₂₀slow cooling to room temperature and maintaining the integrity of the membranes.Compared with V_90-xTi₁₀Mo_x,V_90-xTi₁₀Cr_x under the same conditions had lower membranes breaking temperature at slow cooling,which shows that the increase of Cr content is stronger than Mo in improving the anti-hydrogen embrittlement performance.