不同Co含量Mm（NiCoMnAl）5贮氢合金的低温放电特性

用电化学方法研究了-40℃条件下Co含量对AB5型贮氢合金的放电容量、氢化物分解的稳定性及氢在贮氢合金中的扩散系数等的影响。结果表明：随Co含量的增大，晶胞体积增大，氢化物分解的焓变增大，低温放电容量减小。氢扩散是影响贮氢合金的低温放电性能的重要因素。     

Nb-Ni-Ti体系氢分离合金膜的结构和渗氢性能研究

开展了Nb-Ni-Ti体系氢分离合金膜的结构和渗氢性能研究。采用XRD、SEM分析膜片的相结构和组织特征,利用Devanathan-Stachurski双电解池法测定膜片的氢扩散系数,考察膜片厚度、成分和结构组织对其氢扩散系数的影响。实验结果表明:氢分离膜的氢扩散系数均随膜片厚度的增加而增大。制备的Nb-Ni-Ti体系合金膜都具有两相结构,即先析出相(bcc-Nb(Ni,Ti)固溶体)和共晶相(bcc-Nb(Ni,Ti)+β2-NiTi),个别成分点有少量的第三相NiTi2生成。膜片成分和组织结构对氢扩散系数影响显著,当合金中先析出固溶体相比例增加时,合金中的氢扩散系数也随着增大,而Ni,Ti含量的变化引起共晶相变化,NiTi相及NiTi2相都不同程度增加了共晶相的相比例而引起氢扩散系数的降低,但同时在结构上改善了合金在吸氢膨胀过程中发生的氢脆现象。氢在Nb-Ni-Ti体系氢分离膜中的扩散系数在10-9数量级范围。     

Mg（2-x）MxNi氢化物储氢性能的一种计算方法

通过对Mg(2-x)MxNi(M=Ti,Ag,Al)储氢合金材料的焓变、熵变、吸氢量与组成和键参数之间关系的分析,建立了焓变、熵变和吸氢量的半经验数学模型,得出影响焓变、熵变、平衡氢压和吸氢量的主要因素及其显著性的大小。结果表明：在所研究的合金体系中,电负性差△X和弹性模量G增大,则氢化物的生成焓△H^0负值减小,原子尺寸δ增大时,氢化物的H^0负值增大。氢化物的△S^0随着△X增大而增大。合金弹性模量、原子尺寸、电荷半径和温度越高,材料的储氢量越大,而电子密度越大,材料的储氢量反而越小。     

贮氢合金

贮氢合金能吸收相当于自身体积 10 0 0倍左右的氢气 ,在室温附近能反复进行吸放氢 ,这较之液态氢能将体积相当于它 80 0倍左右的氢气液化有利得多。贮氢合金几乎都是吸氢的金属 (碱土类金属 ,第 3族～第 5族金属及Ｐｄ)与不吸氢的金属 (除Ｐｄ以外的第 6族～第 12族金属 )组合而成的合金。大多根据吸氢金属来对贮氢合金加以分类 ,下表列出了一些主要的贮氢合金的吸氢量、氢平衡压以及氢化物的生成焓。合金 吸氢量ｘ(ＭＨｘ)吸氢量% (质量 ) 分类 1分类 2 结晶构造(合金 )结晶构造(氢化物 )平衡压力 (温度 )Ｐ(Ｔ)/ＭＰａ ,(Ｋ)氢化物生成焓…     

LaNi_xAl_y合金吸氢性能的研究

本文借助X射线衍射法确定了La-Ni-Al三元体系中以LaNi_5为基的固溶体范围。800℃时其范围为:Al<12.2wt-％, 31wt-％相似文献   

TiV0.8-xCr1.2Alx合金的结构与贮氢性能

研究了Al对TiV0.8-xCr1.2Alx(x=0、0.05、0.1、0.15、0.2)合金的结构与贮氢性能的影响.XRD、PCT等测试研究表明:TiV0.8-xCr1.2Alx合金均为单相bcc结构,铸态时主相为树枝状晶组织;随着Al含量由0增加到6.67 at%,合金的晶格常数变大,吸氢量和放氢量减小,氢化物标准生成焓变与生成熵变增大.放氢的平台压随着Al含量的增加而线性增大.TiV0.75Cr1.2Al0.05合金最大吸氢量达3.887%(质量分数),有效吸氢量达2.288%.     

EH36钢的氢陷阱及氢脆敏感性

采用氢渗透测试、慢拉伸试验等研究手段,探究EH36钢表面、1/4和1/2厚度处的氢陷阱、氢扩散系数及氢脆敏感性。结果表明,表面及1/4厚度处的显微组织主要为贝氏体,表面处的显微组织较为细小,1/2厚度处主要为铁素体和珠光体。可逆和不可逆氢陷阱密度由表面到1/2厚度处依次降低,氢扩散系数随之依次增大。随充氢电流密度或时间的增加,各厚度处拉伸试样的屈服强度、抗拉强度、伸长率均有不同程度的降低,氢脆敏感性随之增大;拉伸断口形貌由呈韧性断裂特征的韧窝状逐渐向呈脆性断裂特征的河流状花样转变。表面处的氢脆敏感性最小,1/2厚度处的氢脆敏感性最大;在1/2厚度处的拉伸断口观察到了一些氢致裂纹。     

HYDROGEN ABSORPTION OF LaNi_xAl_y ALLOYS

本文借助X射线衍射法确定了La-Ni-Al三元体系中以LaNi_5为基的固溶体范围。800℃时其范围为:Al<12.2wt-％, 31wt-％相似文献   

钛合金化对Mg_2Ni储氢性能的影响

采用第一性原理方法研究了钛合金化对Mg_2Ni及其氢化物储氢性能的影响。计算结果表明,在掺杂浓度为0~0.5的范围内,Ti优先占据Mg(6i)位,六方结构的固溶体合金Mg_((2-x))TixNi极易分解为立方结构的Mg3TiNi2和六方结构的Mg_2Ni组成的复合相。Ti的掺杂削弱了H原子和Ni原子间的相互作用,降低了其合金体系的吸氢反应焓,提高了Mg2Ni氢化物的解氢能力。     

Zr-2.5Nb合金板材吸氢行为研究

采用电解法对Zr-2.5Nb合金板材进行渗氢,研究不同时间渗氢后试样的吸氢特性;运用X射线衍射仪和金相显微镜对渗氢及热处理后试样的物相结构和显微组织及氢化物分布特征进行分析,并利用LECORH600红外吸收氢测量仪对试样吸氢量进行定量分析。结果表明,合金吸氢后试样表面形成一层氢化物膜,氢化物膜主相为ZrH1.66,氢化物膜厚随着渗氢时间的延长而逐渐增加;合金试样中氢化物呈片状并沿平行板材轧制方向分布,且氢化物随试样吸氢量的增加有聚集生长的趋势,试样的吸氢量随渗氢时间呈抛物线型变化。     

Multiphase and microstructure effects on the hydrogen absorption/desorption behavior of a Ti–22Al–27Nb alloy

The hydrogen absorption/desorption behavior of hydride-forming alloys depends on their microstructure. We investigated multiphase effects on the hydrogen absorption/desorption behavior at 100°C of a ternary alloy [Ti–22Al–27Nb (at.%)] whose microstructure consists of β (bcc) [or its ordered phase β₀ (B2)] and/or O (orthorhombic, based on Ti₂AlNb) phases. On exposing β₀ single-phase specimens to hydrogen, β hydride (B2) is easily formed. However, further hydriding to γ hydride (bct) does not easily occur. When the O phase exists in the β matrix phase, the β→γ hydride transformation occurs and the reversible absorption/desorption of hydrogen between β and γ hydrides is observed. Roles of the O phase in the reversible hydrogen absorption/desorption behavior are discussed on the basis of the crystal structure correlation between the β phase, O phase and γ hydride phase and the ordering of hydrogen atoms in these phases.     

Hydrogen evolution from cathodically charged titanium aluminide alloy Ti–24Al–11Nb

A Ti₃Al-based titanium aluminide alloy, Ti–24Al–11Nb, was cathodically charged with hydrogen in a 5% H₂SO₄ aqueous solution for various charging times, and the formation and dissociation of the hydride, the hydrogen evolution behavior and the total hydrogen uptake were investigated mainly by means of X-ray diffractometry and thermal desorption spectroscopy (TDS). The same kind of hydride phase as observed previously in Ti–25Al alloy (hexagonal hydride) was presumably formed in the Ti–24Al–11Nb alloy after cathodic charging. No damage, such as cracks, was induced by hydrogen charging. Two kinds of TDS peaks, one probably corresponding to hydride dissociation and the other to hydrogen dissolution in the normal lattice site, were found after longer hydrogen charging. It is suggested that niobium addition to Ti₃Al-based titanium aluminide alloy may reduce hydrogen susceptibility during cathodic charging.     

稀有难熔金属中氢的测定

叙述了脉冲加热、惰性气氛熔化法测氢的原理及有关试验条件的选择。结果表明，用Ｓｎ作熔池，选择合适的功率（Ｔｉ、Ｚｒ、Ｈｆ为２５００Ｗ，Ｔａ、Ｎｂ为２７００—２８００Ｗ）、试样量和加热时间（Ｔｉ、Ｚｒ、Ｈｆ及其合金３０ｓ，Ｔａ、Ｎｂ及其合金４０ｓ），可对Ｔｉ、Ｚｒ、Ｈｆ．Ｔａ、Ｎｂ及其合金中的氢进行分析，该法准确度高，优于真空热提取法。     

磁控溅射Pd膜对Zr70Fe5.4V24.6合金吸/放氢性能的影响

采用磁控溅射技术在Zr70Fe5.4V24.6(质量分数,%,下同)合金基体上沉积Pd膜。研究磁控溅射沉积Pd膜的生长特性和显微组织及Pd膜对Zr70Fe5.4V24.6合金吸/放氢性能的影响规律。结果发现,在Zr70Fe5.4V24.6合金基体上磁控溅射沉积的Pd膜具有fcc结构并在(111)晶面有明显的择优取向。对镀膜后合金吸/放氢性能的测试结果表明,磁控溅射沉积Pd膜对Zr70Fe5.4V24.6合金的活化性能及吸氢动力学无显著影响。沉积Pd膜后Zr70Fe5.4V24.6合金可逆吸氢量H/A由0.63增至1.20,吸氢平台增长量约为90%。氢化物形成焓绝对值的平均值增大约77%,生成熵的平均值增大约56%,沉积Pd膜后的合金与氢结合所形成的氢化物更稳定。     

表面充氢对TA2在草酸溶液中腐蚀行为的影响

目的提高TA2在草酸溶液中的耐蚀性,揭示表面充氢提高钛在草酸溶液中耐腐蚀性能的机理。方法采用电化学充氢的方法对TA2试样进行表面充氢,采用SEM和XRD分析充氢对试样表面形貌和相组成的影响,并采用电化学测试和腐蚀浸泡实验研究不同充氢时间的TA2试样在草酸溶液中的耐蚀性。结果电化学充氢后,TA2试样表面会生成一层以Ti H1.5为主要组成相的氢化钛层,该氢化钛层的厚度随充氢时间的延长而增厚。电化学测试结果显示,随着充氢时间的延长,TA2试样在草酸溶液中的自腐蚀电位从–0.7 V(vs.SCE)逐渐增加到0 V左右,腐蚀倾向显著下降;极化电阻Rp则从0.2 kΩ·cm^2逐渐增加到了24.1 kΩ·cm^2,耐蚀性能增强。腐蚀浸泡实验结果表明,随着充氢时间的延长,TA2试样在草酸溶液中的腐蚀程度逐渐减弱,腐蚀速率也从未充氢时的4.63mm/a逐渐下降到0.03mm/a。结论在草酸溶液中,电化学充氢TA2试样表面生成的氢化钛层对Ti基体具有保护作用,并且保护效果随氢化钛层的增厚而增强。试样表面氢化钛层对Ti基体的保护作用除了与成分有关外,还与其结构相关,完整致密的氢化钛层可以对Ti基体起到很好的保护作用,而疏松多孔的氢化钛不仅不能保护Ti基体,反而还会促进Ti基体的腐蚀。     

激光增材制造高Nb含量GH4169合金微观偏析行为研究

目的减轻不同热处理状态下激光增材制造高Nb含量GH4169合金组织中的微观偏析。方法采用激光增材制造方法对球磨Nb合金化后的合金粉末进行快速成形,获得具有较高Nb含量的GH4169合金试样。通过光学显微镜、扫描电子显微镜及能谱分析、维氏硬度测试方法,对沉积态、固溶态和直接时效态试样进行分析,研究因合金中Nb含量变化引起的微观偏析对沉积态和热处理态合金的枝晶组织和显微硬度的影响。结果随着Nb含量的增加,一方面,由于枝晶间的Nb含量增加,枝晶间(γ+Laves)共晶数量增加,且共晶组织形貌更为连续;沉积态试样的显微硬度由228.4HV增大至534.1HV。另一方面,枝晶干Nb元素含量增加,枝晶干与枝晶间Nb元素含量的差异缩小,Nb元素的偏析比由8.59减小至4.13。后续固溶处理后,枝晶结构逐渐消失,枝晶间Laves相的数量随之减少,枝晶干与枝晶间的微观偏析减轻;固溶态试样硬度值随之减小,减小趋势随固溶温度的升高而逐渐平缓。随着Nb含量的增加,直接时效处理后,各试样显微硬度值在微观区域内的均匀性提高,枝晶干与枝晶间强化相的析出差异减小。结论合适的热处理制度既可以实现合金元素的均匀化,还能减小枝晶干与枝晶间强化相的析出差异,减轻激光增材制造高Nb含量GH4169合金组织中的微观偏析。     

脉冲加热-红外法测定钽、铌中氢量

本文对应用TCH600氧氮氢分析仪脉冲加热-红外吸收法测定钽、铌中氢量的提取功率、分析积分时间、积分延迟时间、比较器水平、称样量等主要分析参数进行了较详细的试验和研究,结果表明,上述最佳参数分别为45 s,10 s,1%,0.05～0.1g。采用原冶金部行业标准铌粉以及LECO公司钛标中的氢量建立校正曲线。以此建立的分析方法对氢标准物质和样品进行准确度、精密度试验,标准测定值与认定值相吻合,相对标准偏差RSD在2.0%～4.2%之间(n=5)。     

Effect of Hydrogen on Alpha Titanium Alloy

The effect of up to 200 ppm hydrogen on the microstructure and mechanical properties of high-purity titanium containing oxygen, nitrogen, tin, and aluminum was investigated. Increasing the hydrogen content resulted in precipitation of a hydride phase and decreased the notch-bend impact strength of the alloys containing oxygen, nitrogen, and tin, similar to the hydrogen embrittlement of unalloyed high-purity titanium. No hydride precipitation or significant embrittlement of the Ti-5AI alloy was found with up to 180 ppm hydrogen.     

Hydriding/dehydriding properties of Mg-Ni-based ternary alloys synthesized by mechanical grinding

The Mg-Ni-based ternary alloys Mg2-xTixNi(x=0, 0.2, 0.4) and Mg2Ni1-xZrx(x=0, 0.2, 0.4) were successfully synthesized by mechanical grinding. The phases in the alloys and the hydriding/dehydriding properties of the alloys were investigated. Mg2Ni and Mg are the main hydrogen absorption phases in the alloys by XRD analysis. Hydriding kinetics curves of the alloys indicate that the hydrogen absorption rate increases after partial substitution of Ti for Mg and Zr for Ni. According to the measurement of pressure-concentration-isotherms and Van't Hoff equation, the relationship between ln p(H2) and 1 000/T was established. It is found that while increasing the content of correspondingly substituted elements at the same temperature, the equilibrium pressure of dehydriding increases, the enthalpy change and the stability of the alloy hydride decrease.     

Hydrogen storage alloys for high-pressure suprapure hydrogen compressor

In this work, AB₅ type rare earth-based and AB₂ type TiCr₂-based hydrogen storage alloys were studied for the purpose of high-pressure hydrogen compression. A pair of hydrogen storage alloys, Ml_0.55Mm_0.2Ca_0.25Ni₅ (Ml: La-rich mischmetal; Mm: Ce-rich mischmetal) and (Ti_0.97Zr_0.03)_1.1Cr_1.6Mn_0.4, with favorable hydrogen storage properties was developed as the alloys for a double-stage high-pressure metal hydride hydrogen compressor (MHHC). With the developed alloy pair, we designed and built a MHHC prototype with hydrogen capacity of 100 L, which could produce high-pressure ultrapure hydrogen with pressure of 45 MPa and purity of 99.9999% from industrial grade hydrogen (98% purity) at pressure of around 2 MPa. During the compression procedure, only hot water is used as the heating source. The compression characteristics were studied and the thermal efficiency was calculated.