Al含量对铸态V-Alx合金组织和力学性能的影响

Effect of Al Content on Microstructure and Mechanical Properties of As-cast V-Alx Alloy

V-Al合金膜有着良好的抗氢脆性和高的氢渗透率,有望成为未来取代Pd合金膜的替代材料。V-Al合金的显微组织不仅影响氢分离性能,还将影响强度和塑性成形性能。本研究通过真空非自耗电弧炉熔炼制备了氢分离用V-Alx(x=5,10,20,30,at%,下同)合金。利用扫描电镜/能谱仪、X射线衍射仪及拉伸试验机和维氏硬度仪等手段,研究了Al含量对铸态V-Alx合金微观组织和力学性能的影响。结果表明:V-Alx合金凝固组织均由V基固溶体及Al2O3粒子组成。Al元素的添加对合金有细化晶粒的作用,随Al含量增加,合金晶粒尺寸减小。当Al元素含量为5at%时,合金抗拉强度达到最大,为236MPa,比纯V提高了12%,这是细晶强化、固溶强化和析出强化的共同结果,此时延伸率相比纯V略有降低。当Al元素含量达到10at%及以上时,Al2O3粒子发生粗化导致合金抗拉强度下降,延伸率急剧下降,合金失去塑性。

V-Al alloy membrane has good resistance to hydrogen embrittlement and high hydrogen permeability, which is expected to become a substitute material for replacing Pd alloy membrane in the future. The microstructure of V-Al alloy affects not only the hydrogen separation performance, but also the strength and plastic forming properties. A series of binary alloys of V-Alx(x=5, 10, 20, 30, at%) were prepared by vacuum non-consumable arc melting. The effect of Al content on microstructure evolution and mechanical properties of as-cast V-Alx alloy was investigated by scanning electron microscopy(SEM), X-ray diffraction(XRD), Vickers hardness tester and tensile testing machine. The results show that the solidification microstructure of these V-Alx alloys is composed of V-based solid solution and Al2 O3 particles. The addition of Al element results in grain refinement, and causes the reduction of grain size with the increase of the Al content. When the content of Al element is 5 at%, the elongation of the alloy slightly reduces, but the tensile strength reaches a maximum of 236 MPa, which is 12% higher than that of pure V. This is attributed to the combined effect of both solid-solution hardening and precipitation strengthening. When the content of Al element reaches 10 at% or more, the Al2 O3 particles coarsen, the tensile strength of the alloy decreases, the elongation decreases sharply, and the alloy loses plasticity.