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多相V-Ti-Ni氢分离合金制备成形工艺及组织性能研究

作者:优质期刊论文发表网  来源:www.yzqkw.com  发布时间:2019/10/29 8:12:43  

摘要:随着化石燃料的广泛使用,环境污染问题日益严重。人们对清洁能源氢的需求日益增加。效率高、成本低和成形性能好的金属氢提纯膜材料受到广泛关注。目前商业化较高的Pd-Ag合金膜,由于Pd的总量少产能低,使其广泛使用受到严重阻碍。V-Ti-Ni系列合金由于成本低、机械性能好和氢渗透性能强,被认为是新一代氢提纯膜材料。本文对V-Ti-Ni系列合金中的V60Ti20Ni20、V70Ti15Ni15和V80Ti10Ni10三种合金的组织、热处理工艺、力学性能及氢分离性能进行研究,优化合金成分和热处理参数,并对合金轧制性能进行相关研究,旨在促进V-Ti-Ni合金膜的推广应用。

首先,对氩弧熔炼的制备的V60Ti20Ni20、V70Ti15Ni15和V80Ti10Ni10三种合金组织的构成与元素分布进行分析。利用SEM对合金的组成进行观察。根据各相衬度的不同,确定合金中有三种不同的合金组织。利用EDS和XRD对合金元素分布的分析,确定合金中不同衬度的相为V基固溶体、NiTi相和NiTi2相。为了解三种合金的透氢性能情况,对三种合金进行透氢试验。V80Ti10Ni10合金在透氢试验初期时,透氢量就迅速升高,合金发生氢脆破裂。V70Ti15Ni15合金进行透氢试验,当进气侧压强小于0.45MPa时,合金透氢量随着进气侧压强的增大而增加;当进气侧表面压强大于等于0.45MPa时,合金透氢量迅速增大,合金发生破裂。V60Ti20Ni20合金在进行透氢试验时,合金的透氢量随着透氢进气侧表面压强的增大而增强,并且未发生氢脆破裂。与V70Ti15Ni15合金在相同压强下的透氢量进行对比发现,V70Ti15Ni15合金的透氢量高。当压强超过0.55MPa时,V60Ti20Ni20合金的透氢量明显高于V70Ti15Ni15合金最大值。

针对三种合金进气侧压强承受能力的不同,对V60Ti20Ni20、V70Ti15Ni15和V80Ti10Ni10三种合金进行拉伸试验。研究表明,三种合金的断裂方式均为脆性断裂。但V60Ti20Ni20合金延伸率和断面收缩率明显好于V70Ti15Ni15和V80Ti10Ni10合金。从断口分析可以发现,V60Ti20Ni20合金断口有韧窝、二次裂纹存在和少量且尺寸较小解理面的出现。V70Ti15Ni15合金断口明确有韧窝和二次裂纹的存在。相对于V60Ti20Ni20合金,尺寸整体偏小。V80Ti10Ni10合金断口为解理断面,其为低能断裂方式。所以作为轧制对象的合金为V60Ti20Ni20合金。

为了提高合金膜的轧制成形能力,分析热处理工艺对合金显微组织和力学性能的影响,优化热处理工艺参数。对V60Ti20Ni20合金进行不同温度和不同时间下的热处理。分别分析热处理时间对合金各相分布的影响和热处理温度对合金各相分布的影响。为了给后来研究者对V70Ti15Ni15和V80Ti10Ni10合金研究时提供参考,对这两种合金也进行了相应条件下的热处理和分析。研究表明,V60Ti20Ni20合金在热处理的作用下,富Ti区减小,元素分布趋于均匀化,NiTi2相细化。但当保温时间为21h,热处理温度分别为800℃和850℃时,枝晶间区域NiTi2相增多。与硬度变化对照发现,合金硬度也有所升高。最终确定轧制前对合金进行热处理参数为:加热温度为850℃,保温时间为18h。热处理使得V70Ti15Ni15和V80Ti10Ni10合金枝晶间区域的NiTi2相减少。V70Ti15Ni15和V80Ti10Ni10两种合金在热处理温度一定的情况下,合金硬度随保温时间的增长而降低。三种合金硬度进行对比发现,相同热处理条件下V60Ti20Ni20合金的硬度值比V70Ti15Ni15和V80Ti10Ni10两种合金的高。

分析轧制对V60Ti20Ni20合金轧制的影响。当V60Ti20Ni20合金压下量为80%时,合金显微组织出现明显的流变现象。在20%预设压下量进行轧制对比发现,合金微观组织未出现流变现象,但合金硬度随压下量的增大而升高。通过XRD谱进行对比发现,合金为温度和压下量都有利于合金晶粒在(200)晶面的取向的出现。但随轧制加热温度的升高,晶粒在(220)晶面取向性有所增强。

With the widespread use of fossil fuels,environmental pollution is becoming more and more serious.The demand forhydrogen in clean energy is increasing.Hydrogen purification membrane materialswith high efficiency, low cost and good formability have attracted wideattention. At present, the commercialized Pd-Ag alloy membrane is seriouslyhindered because of its low total amount of Pd and low productivity. V-Ti-Niseries alloys are considered as the new generation of hydrogen purificationmembrane materials due to their low cost, good mechanical properties and stronghydrogen permeability. In this paper, the microstructure, heat treatmentprocess, mechanical properties and rolling properties of three alloys ofV60Ti20Ni20, V70Ti15Ni15 and V80Ti10Ni10 alloys in V-Ti-Ni series alloys arestudied to promote the popularization and application of V-Ti-Ni alloy film.

First, the composition and elementdistribution of three kinds of alloy V60Ti20Ni20, V70Ti15Ni15 and V80Ti10Ni10prepared by Ar arc melting were analyzed. The composition of the alloy wasobserved by SEM. According to the contrast of each phase, there are threedifferent alloy structures in the alloy. Using EDS and XRD to analyze thedistribution of alloying elements, it is determined that the phases of alloywith different liners are V based solid solution, NiTi phase and NiTi2 phase.In order to understand the hydrogen permeation performance of the three alloys,three kinds of alloys were tested for hydrogen permeation. During the initialstage of hydrogen permeation, the hydrogen permeation rate of V80Ti10Ni10 alloyincreased rapidly, and the hydrogen brittleness fracture of the alloy occurred.The hydrogen permeation test of V70Ti15Ni15 alloy is carried out. When theinlet side pressure is less than 0.45MPa, the hydrogen permeation rateincreases with the increase of inlet side pressure. When the inlet surfacepressure is greater than or equal to 0.45MPa, the hydrogen permeability of thealloy increases rapidly, and the alloy ruptures. When hydrogen permeation testwas carried out, the hydrogen permeation of V60Ti20Ni20 alloy increased withthe increase of the surface pressure of the hydrogen inlet side, and nohydrogen embrittlement fracture occurred. Compared with the hydrogen permeationcapacity of V70Ti15Ni15 alloy under the same pressure, it is found that thehydrogen permeation of V70Ti15Ni15 alloy is high. When the pressure exceeds0.55MPa, the hydrogen permeation of V60Ti20Ni20 alloy is significantly higherthan that of V70Ti15Ni15 alloy.

Aiming at the difference of the bearingcapacity of three kinds of alloys, the tensile tests of three kinds of alloysV60Ti20Ni20, V70Ti15Ni15 and V80Ti10Ni10 were carried out. The results showthat the fracture modes of the three alloys are brittle fracture. But theelongation and section shrinkage of V60Ti20Ni20 alloy are obviously better thanV70Ti15Ni15 and V80Ti10Ni10 alloys. From fracture analysis, it is found thatthere are dimples, two cracks and small amount of V60Ti20Ni20 cracks. Thefracture of V70Ti15Ni15 alloy has the existence of dimple and two cracks.Compared with V60Ti20Ni20 alloy, the size of the alloy is relatively small. Thefracture of V80Ti10Ni10 alloy is cleavage section, and it is a low-energyfracture mode. So the alloy as rolling object is V60Ti20Ni20 alloy.

In order to improve the rolling formingability of the alloy film, the influence of heat treatment process on themicrostructure and mechanical properties of the alloy was analyzed, and theheat treatment process parameters were optimized. Therefore, the V60Ti20Ni20alloy was heat-treated at different temperatures and time. The effects of heattreatment time and heat treatment temperature on the distribution of alloyphases were analyzed respectively. In order to provide reference for theresearch of V70Ti15Ni15 and V80Ti10Ni10 alloys, the heat treatment and analysisof the two alloys were also carried out.

关键词:合金组织;热处理;力学性能;氢渗透;轧制

Alloy structure; Heat treatment; Mechanicalproperties; Hydrogen permeation; Rolling

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