Hydrogen sorption properties of V85Ni15

An alloy with nominal composition V₈₅Ni₁₅ was prepared in a vacuum induction melting apparatus. The chemical analysis of the sample showed a V (Ni) content of 82.63 (15.68) at% and small contaminations by carbon and aluminum. XRD measurements confirmed that the bcc Ni-V solid solution phase is the main constituent of the sample. However, a minor impurity (approximately 6.5 wt%) due to the precipitation of the sigma NiV_3-x phase is present in the sample.Hydrogen sorption measurements extending from 150 °C up to 400 °C in a wide pressure range (up to 90 bar) were performed. Upon hydrogenation below 250 °C, one observes the subsequent presence of an α phase and of two hydride phases with different values of dehydrogenation enthalpy: ΔH_dehydr = 21 ± 1 kJ/mol for 0.15 ≤ H/M ≤ 0.30 and ΔH_dehydr = 26 ± 2 kJ/mol for 0.53 ≤ H/M ≤ 0.59. Above 300 °C, there is no evidence of the formation of hydrides and only an α phase is present up to the maximum measured composition, with a hydrogenation enthalpy ΔH_hydr = 10.0 ± 0.5 kJ/mol.     

多次真空固溶处理对GH1131高温合金组织和力学性能的影响

利用真空高压气淬工艺研究了GH1131高温合金经1100~1170 ℃范围内多次真空固溶处理后的组织和力学性能。结果表明,固溶态组织包含奥氏体晶粒和颗粒状碳化物,且随着固溶温度的升高,晶粒度稍有增大趋势。GH1131高温合金经多次真空固溶处理后组织均匀,常温与高温力学性能稳定,经1100 ℃+1130 ℃+1170 ℃三次真空固溶处理后,晶粒度维持了6~8级,900 ℃高温抗拉强度达到200 MPa。     

组合赋权的TOPSIS在冲击地压危险性评价中的应用

为了合理准确地评价煤矿冲击地压危险性,在现有评价冲击地压危险性实例的基础上,从煤矿地质因素和开采因素2个方面,选取10个主要的影响指标,利用熵权法和指标相关性权重法分别计算影响冲击地压危险性的各评价指标权重,再根据组合赋权的方法得出各指标的综合权重,构建基于逼近理想解理论的冲击地压危险性评价模型。以重庆砚石台煤矿为例,选取20组评价冲击地压危险性样本数据进行分析,确定评价冲击地压危险性的最优和最劣状况,然后计算出各个评价方案与最优和最劣状况的距离,最后综合最优与最劣距离,确定评价对象的相对贴近度。应用结果表明:评价结果与实际情况一致,且该模型相较其他模型的评价结果更加科学准确,表明该方法有良好的实用价值。     

汽车用钢弹性模量测试探讨

采用静态拉伸试验方法对系列汽车用钢材料进行测试，得到了汽车用钢材料的弹性模量，分析了强化方式、轧制方向、塑性变形等对材料弹性模量的影响。结果表明：强化方式影响材料的弹性模量，固溶强化的汽车用钢材料弹性模量最大；材料的弹性模量表现出各向异性特点，垂直于轧制方向的弹性模量最大；塑性变形降低材料的弹性模量。研究结果为工程设计、冲压模拟、碰撞模拟、回弹模拟等提供计算依据。     

Scandium recovery from raffinate copper leach solution as potential new source with ion exchange method

Raffinate copper leach solution of the Iran Sarcheshmeh copper complex has up to 3 mg/L scandium (Sc), which is significantly better than many existing sources, making it a possible source for the recovery of Sc using the ion exchange method. Visual Minteq software was employed to ascertain the ionic species likely to be formed under operational conditions in the mine and for selecting the suitable ion exchange resin. The cationic resin thus chosen was employed statically with ions-bearing synthesized solutions and statically/dynamically for actual copper mining raffinate solution. Room temperature and pH of 1.5 showed the highest Sc adsorption. The dynamic tests established the full saturation of the resin at 450 BV of the raffinate solution flow. Using sodium carbonate for elution, desorption of Sc, Y and Ce from the resin during static elution tests at constant duration was higher than that of Fe, Al and Cu. The results from the dynamic tests followed similar trends for the priority and the extent of the elution process. Desorption results from specimens of dynamic tests show a 60:1 concentration ratio leading to a 186 mg/L Sc-rich solution.     

Coherency strain induced hardening in bulk polycrystalline ceramics: A case study with MgO-based “ceramic alloys”

The role of coherency strain at the matrix/precipitate interface toward hardening of bulk polycrystalline “ceramic alloys” has been established here. Formation of “near ideal” bulk polycrystalline ceramic microstructure characterized by the presence of uniformly distributed coherent “ultra-fine” MgCr₂O₄ particles (size: ~25 nm) within matrix (MgO) grains was achieved via solid-state precipitation during aging treatment of bulk supersaturated MgO–Cr₂O₃ solid solutions (formed during pressureless sintering in air, followed by fast cooling). The as-aged MgO–MgCr₂O₄ “ceramic alloys” exhibited hardness increment by ~73% over that of phase pure bulk MgO upon aging for just 10 hours at 1000°C in air. Evidences toward the presence of significant coherency strains across the MgO/MgCr₂O₄ coherent interfaces were obtained with transmission electron microscopy. Analysis based on hardening mechanisms and comparisons with MgO–MgFe₂O₄ system, having lesser hardening due to lower misfit strain at MgO/MgFe₂O₄ coherent interfaces (despite greater content of second-phase particles), confirm the dominant role of coherency strains toward hardness enhancement in “ceramic alloys.”     

耦合效应下压力型锚索锚固机理的近似理论分析

为了更加精确地研究压力型锚索的锚固机理,基于锚索预应力与岩土体蠕变的耦合效应推导了锚索预应力方程。在此基础上根据Mindlin问题解,推导了耦合效应作用下锚索砂浆体的压应力和剪应力近似解,并考虑锚索预应力与岩土体蠕变之间的耦合效应进行了案例分析。研究结果表明:锚索预应力和砂浆体受到的应力峰值均按反幂函数随时间逐渐衰减并稳定;承压板的长宽比与压应力峰值之间存在正相关关系,与剪应力峰值之间存在负相关关系;岩土体的泊松比与应力峰值之间存在正相关关系。该成果丰富了压力型锚索锚固机理的理论研究,可为边坡锚固设计提供一定的理论依据。     

基于稳定固溶体团簇模型的无扩散阻挡Cu合金薄膜的成分设计

随着超大规模集成电路的发展,器件特征尺寸不断缩小,必然会出现Cu互连扩散阻挡层厚度无法进一步减小等瓶颈问题。因此,开发新型无扩散阻挡层Cu合金薄膜(Cu种籽层)势在必行。该新型互连结构在长时间的中高温(400~500℃)后续工艺实施过程中,需同时具备高的稳定性(不发生互扩散反应)和低的电阻率。基于此,首先综述了目前无扩散阻挡层结构的研究现状及问题,然后对基于稳定固溶体团簇模型设计制备的无扩散阻挡Cu-Ni-M薄膜的研究工作进行了梳理,通过多系列薄膜微观结构、电阻率及稳定性的对比,深入探讨了第三组元M的选择原则及其对薄膜热稳定性的影响。为进一步验证稳定固溶体团簇模型的有效性,对第二组元的变化进行了相关讨论。结果证实,选取原子半径略大于Cu、难扩散且难溶的元素作为第三组元M,薄膜表现出良好的扩散阻挡能力;当M/Ni=1/12,即合金元素完全以团簇形式固溶于Cu基体时,薄膜综合性能达到最优,能够满足微电子行业的要求。所有研究表明,稳定固溶体团簇模型在无扩散阻挡层Cu合金薄膜的成分设计方面十分有效,该模型也有望在耐高温Cu合金及抗辐照材料成分设计方面推广使用。     

T4和T6热处理对Mg-2.5Zn-1.5Ca-0.22Zr合金组织和硬度的影响

采用光学显微镜、扫描电镜和显微硬度仪等研究了T4和T6热处理对Mg-2.5Zn-1.5Ca-0.22Zr镁合金显微组织及硬度的影响。结果表明:Mg-2.5Zn-1.5Ca-0.22Zr镁合金经T4热处理之后,网状结构的β-Ca2Mg6Zn3相逐渐分解并转变为不规则的团聚的块状结构,MgZn2相逐渐溶解于α-Mg基体中,硬度比铸态时显著提高,达到63.87 HV;经过不同时间的T6热处理之后,MgZn2相从α-Mg基体中重新析出,球状的Mg2Ca中间化合物均匀的分布于晶粒内且发生明显长大。随着时效时间的延长,MgZn2相增多,对位错的钉扎增强,合金的硬度提高,在"峰时效"时的硬度达到64.97 HV。410℃×24 h固溶处理后150℃×8 h时效处理为Mg-2.5Zn-1.5Ca-0.22Zr镁合金的最佳热处理工艺。     

Phase equilibria studies in the CaO–SiO2–Al2O3–MgO system with CaO/SiO2 ratio of 0.9

Phase equilibria and liquidus temperatures in the CaO–SiO₂–Al₂O₃–MgO system at a CaO/SiO₂ weight ratio of 0.9 in the liquid phase have been experimentally determined employing high-temperature equilibration and quenching technique followed by electron probe X-ray microanalysis. Isotherms at 1573, 1623, 1673, and 1773 K were determined and the primary phase fields of wollastonite, melilite, olivine, periclase, spinel, and corundum have been located. Compositions of the olivine and melilite solid solutions were analyzed and discussed. Comparisons between the newly constructed diagram, existing data, and FactSage predicted phase diagrams were performed and differences were discussed. The present study will be useful for guidance of industrial practices and further development of thermodynamic modeling.