AlSi10Mg的激光选区熔化成形研究

利用激光选区熔化(selective laser melting,SLM)成形技术对Al Si10Mg铸造铝合金的成形进行了工艺研究,获得了致密的成形,并对其沉积态和热处理态试样进行了静态拉伸性能测试和显微组织分析。结果表明:对于Al Si10Mg,其SLM沉积态的常温拉伸强度远高于铸件标准,延伸率与铸态相当;退火工艺对SLM试样的组织及力学性能有着重要的影响,随着退火温度的提高,试样微观组织发生改变,在300℃、2 h退火工艺下,原本均匀分布的颗粒状Si聚集长大为针状,使得试样的强度下降,延伸率升高。抗拉强度由沉积态的507~518 MPa下降到378~406 MPa,延伸率由沉积态的3.0%~3.5%增加到6.5%~9.5%。     

丝材成分对电弧增材Al-Cu合金组织及力学性能的影响

针对电弧增材制造Al-Cu合金力学性能非均匀问题,采用不同成分的丝材研究了Cu含量及Fe、Si杂质含量对热处理后成形组织及力学性能的影响。结果表明:Cu含量低(5.3%,质量分数),α(Al)基体中固溶Cu含量不足,成形试样屈服强度显著降低,Cu含量适中(5.8%～6.5%),成形组织中残余少量θ相(Al_2Cu),对塑性影响较小,成形试样强度提高;在Cu含量适中、Si含量较低(ω(Si)0.08%)时,随着Fe含量增加,成形组织中残余的块状或条状α(Fe)相增加,α(Al)基体中固溶Cu含量减少,成形试样屈服强度降低;在Cu含量适中,Fe、Si含量较高时(0.15%),成形试样层间形成的针状β(Fe)相增加,垂直方向塑性显著降低;严格控制丝材中Fe、Si杂质含量(Si少于0.08%,Fe少于0.15%),Cu含量适中(5.8%～6.5%),成形试样无明显各向异性,平均抗拉强度、屈服强度、断后伸长率分别超过440 MPa、300 MPa、10%。     

Al-Si-Mg-Y合金消失模铸造振动压力凝固的组织与性能

应用消失模铸造振动压力凝固成形技术制备了Al-7Si-0.8Mg-0.3Y(ASMY)合金。通过SEM、XRD、DSC和TEM等测试方法对其铸态和T6组织进行分析,研究其对力学性能的影响。结果表明:在ASMY合金铸态组织的晶界处生成有少量Al3Y短棒状颗粒相;在T6热处理过程中,稀土Y或Al3Y阻碍Mg2Si相的析出和扩散聚集,使析出相Mg2Si呈弥散分布;Mg2Si相与晶界稳定相Al3Y对合金同时起到钉扎强化作用;采用消失模铸造振动压力凝固技术后,铝合金的孔隙率显著降低,从1.1%降低0.18%;ASMY合金消失模铸造振动压力凝固试样T6态的抗拉强度达到308MPa,比A356普通消失模试样T6态的抗拉强度提高29%。     

热挤压对挤压过共晶Al-17.5Si合金组织与性能的影响

对过共晶Al-17.5Si合金热挤压成形后的组织与性能进行了研究。结果发现,挤压铸造Al-17.5Si合金的共晶组织明显细化,板片状的共晶Si相变为细小珊瑚状。并且,随着挤压比压的增大,粗大的初生Si相显著减少,α-Al枝晶越来越发达。对其进行热挤压后,发达的α-Al枝晶消失,细小珊瑚状的共晶Si相完全破碎为小粒状弥散分布在基体中。其力学性能大幅提高,塑性得到显著的改善。在320 MPa比压下铸造的坯锭再经热挤压成形后,其抗拉强度和伸长率分别达到158.82 MPa和11.65%,比重力铸造的分别提高了84.13%和441.86%。     

间接挤压铸造Al-11Si-3Cu-Mg合金的组织、性能和偏析行为

研究了Al-11Si-3Cu-Mg合金在间接挤压铸造工艺下的微观组织、力学性能和Si、Cu元素偏析行为。结果表明，在110 MPa压力下，间接挤压铸造成形的试样截面处的微观组织呈现出明显的不均匀性，表现为外层细小α-Al固溶体枝晶，内层为粗大枝晶，Al-Si共晶组织分布在α-Al固溶体枝晶间隙，在局部形成较大的偏聚块，内外层中间形成一圈Al-Si共晶组织和富Cu相的偏聚环；经T6热处理后，其抗拉强度为443 MPa,屈服强度为312 MPa,伸长率为2.85%。在试样截面处从中心到边缘进行能谱分析，发现外层Si和Cu元素在重力作用下呈正偏析，内层在压力作用下呈现负偏析；元素偏析越严重，越容易形成裂纹，对力学性能产生不利影响。     

电弧增材制造(WAAM)Al-7Si-0.6Mg-xFe组织与性能的研究

本文研究了Fe含量对WAAM Al-7Si-0.6Mg合金组织与性能的影响,并观察了合金中富Fe相形貌和分布。结果表明,WAAM成形试样中富Fe相为细小针状,为亚稳态镁硅相和π-Fe相的混合相。经T6热处理后,富Fe相中Mg₂Si脱溶而形成π-Fe相。随着Fe含量的增加,合金中的富Fe相的尺寸增大、数量增多。Fe含量在较小的范围内变化即可对WAAM成形合金的延伸率产生较大影响,而对强度作用不明显,当Fe含量由0.11%增加到0.18%,合金的断裂延伸率降低了47.1%。     

SLM成形和热处理对AlSi10Mg合金组织与性能的影响

与重力铸造AlSi10Mg合金相比,激光选区熔化成形过程中产生细小的晶粒,在α-Al基体中的粗大块状或针状Si相变为网格状且均匀分布。由于激光选区熔化成形过程中冷却速度较快,形成了过饱和固溶体,其抗拉强度、屈服强度和伸长率分别为483MPa、314MPa和6.43%。经T6处理后,均匀网络状的Si相发生溶解、断裂,并且聚集长大为圆整钝化的不规则形状,以及成细小弥散分布的Si相,合金的抗拉强度和屈服强度降低至208MPa、167MPa,伸长率提高至10.37%。     

快速凝固粉末冶金TiB2颗粒增强AlFeVSi耐热铝合金

利用快速凝固粉末冶金方法制备了TiB2颗粒增强Al-8.5Fe-1.3V-1.7Si耐热铝合金试样以及不含TiB2颗粒的基体合金试样,通过光学显微镜、扫描电镜分析了其显微组织和断口形貌,采用X射线衍射进行了物相分析,并进行力学性能测试.结果发现,TiB2颗粒能有效地添加到Al-8.5Fe-1.3V-1.7Si耐热铝合金基体中,并能有效地抑制平衡相Al13Fe4的析出,且能细化晶粒,TiB2颗粒的存在使得粒度小于74μm粉末冶金合金挤压试样的室温强度高达454.1 MPa,屈服强度达407.8 MPa,延伸率保持在7.7%;350℃高温强度稳定在210 MPa以上,延伸率稳定在7.7%以上.     

热处理对选区激光熔化成形M2052合金组织性能的影响

目的综合提升选区激光熔化(Selective Laser Melting,SLM)成形M2052锰铜合金的力学性能。方法利用SLM技术成形M2052锰铜合金,并通过固溶、时效及固溶+时效等热处理方法对其成形态组织进行调控。通过扫描电子显微镜和X射线衍射仪,对合金的显微组织、晶粒形貌、拉伸断口形貌及物相组成进行分析,并通过拉伸性能、冲击性能测试,分别评价SLM成形及热处理后的屈服强度、抗拉强度、延伸率和冲击韧性。结果 SLM成形的M2052合金经过固溶处理后,形成了典型的类孪晶结构;时效处理后的组织和SLM成形态类似,形成了细微的亚孪晶组织;固溶+时效处理后,类孪晶组织粗大。四种状态的显微组织均由单相γ固溶体组成,时效态和固溶+时效态析出了α-Mn相,但时效态析出含量较多。SLM成形态具有较高的抗拉强度σb和屈服强度σp0.2(636 MPa和548 MPa),时效处理能提高合金的σb和σp0.2(707MPa和570MPa),但是冲击韧性和延伸率(5.5J和8.5%)较差;而固溶处理能显著提高合金的冲击韧性和延伸率(23.5 J和22.25%)。综合比较,固溶+时效态试样具有最好的力学性能(冲击韧性为17 J,延伸率为10.8%,σb为503 MPa和σp0.2为322.5 MPa)。断口分析表明,四种状态下均为韧性断裂。结论固溶+时效热处理可以在存在单相γ固溶体条件下析出少量的α-Mn相,综合提升锰铜合金的力学性能。     

铸造方法对Al-Mg-Mn-Ce合金组织和力学性能的影响

采用砂型铸造、金属型铸造和压铸制备了Al-5.0Mg-0.6Mn-0.25Ce合金,研究了不同铸造方法(冷却速率)对合金组织和力学性能的影响。结果表明,随着冷却速率增加,铸态合金中的α-Al枝晶发生等轴化,粗大的第二相发生细化。低冷却速率时,砂型铸造、金属型铸造合金的铸态组织主要由α-Al枝晶和分布在周围的Al_3Mg_2相、Al_6(Fe,Mn)相、Mg_2Si相等第二相组成;高冷却速率时,压铸合金则由α-Al等轴晶和分布在其周围的短棒状含Mn相、针状Mg_2Si相组成。随着冷却速率增加,铸态合金的屈服强度、抗拉强度逐渐增加,而伸长率则呈现先增后减的趋势,这主要是与合金显微组织和内部气孔、缩孔等缺陷有关。冷却速率越高,合金组织越细,并且Mg、Mn固溶在α-Al基体内的含量增多,所以合金强度越高。然而,压铸合金中,组织内存在气孔和针状Mg_2Si相降低了合金的塑性。     

Coprecipitation thermodynamics of iron(II-III) hydroxysulphate green rust from Fe(II) and Fe(III) salts

Iron(II-III) hydroxysulphate GR(SO₄²⁻) was prepared by precipitating a mixture of Fe(II) and Fe(III) sulphate solutions with NaOH, accompanied in most cases by iron(II) hydroxide, spinel iron oxide(s) or goethite. Its [Fe(II)]/[Fe(III)] ratio determined by transmission Mössbauer spectroscopy was 2±0.2, whatever the initial [Fe(II)]/[Fe(III)] ratio in solution. Proportion of Fe(OH)₂ increased when the initial [Fe(II)]/[Fe(III)] ratio increased, whereas proportion of α-FeOOH or spinel oxide(s) increased when this ratio decreased. GR(SO₄²⁻) is metastable vs. Fe₃O₄ except in a limited domain around neutral pH. Precipitation from solutions containing both Fe(II) and Fe(III) dissolved species seems to favour GRs formation with respect to stable systems involving iron (oxyhydr)oxides.     

STRUCTURAL REFINEMENT FOR Nd_2(Fe_(0.9)Si_(0.1))_(14) B FROM NEUTRON DIFFRACTION MEASUREMENT

Neutron diffraction measurements on Nd2(Fe0,Si0 ,)14B at room temperature and 77 K were performed. Data analysis using profile refinement was carried out. The results show that at room temperature Si atoms occupy preferentially 4c, 8j, and I6k2 sites, and the magnetic moments of bath Nd and Fe are parallel to C—axis. At 77 K, the site occupations remain unchanged as in room temperature, while the calculated Nd magnetic moment direction has an angular deviation of 37.8 ° from C—axis.     

阿司匹林-烟酰胺-锌络合物对血小板聚集作用和实验性血栓形成的影响

目的: 对阿司匹林-烟酰胺-锌络合物(WUY)的抗血小板聚集作用和抗实验性血栓形成作用进行研究。方法: 用 Born 法测定 WUY 对抗腺苷二磷酸钠(ADP)、花生四烯酸(AA) 和胶原诱导大鼠体外或体内血小板最大聚集, 用小鼠静注 AA 引起的死亡率以及大鼠实验性血栓形成研究药物的抗血栓作用, 并且用放免法测定家兔口服药物后血小板释放产物血栓烷 B₂ (TXB₂) 和 6-酮前列腺素 F_1α (6-keto-PGF_1α) 的含量。结果: WUY 高、中、低 3 种剂量在体外都能显著对抗诱导剂(ADP、AA 和胶原) 引起的血小板聚集, 其中高剂量组的抗血小板聚集作用比阿司匹林(ASP) 强。在体内, WUY 明显抑制 AA 诱导的血小板聚集作用, 1 h 和 3 h 作用最强。WUY 对小鼠尾静脉注射 AA 后诱发的肺栓塞死亡有较强的预防作用, ED₅₀ 比ASP 低, 对大鼠实验性血栓形成也有显著的抑制作用。WUY 高剂量能显著抑制血浆中TXB₂ 水平和提高血浆中6-keto-PGF_1α 含量, 而ASP则降低血浆中 TXB₂ 和 6-keto-PGF_1α 的水平。结论: WUY 具有比ASP 更强的抗血小板聚集作用和抗实验性血栓形成作用, 并能提高血浆中 6-keto-PGF 1α 含量。     

Understanding Solid-Solid (fcc→ω+bcc) Transition at Atomic Scale

An atomic transition model of a face-centered cubic (fcc) crystal to a primitive hexagonal ω and body-centered cubic (bcc) structures has been crystallographically built. The fcc structure can transform into the ω structure through a local shuffling or displacement of atoms about 0.4014 Å in iron for a _{fcc iron} = 3.59 Å. The bcc structure can form either after the ω formation or concurrently by the similar mechanism, or the ω structure can be treated as an intermediate stage during the transition of fcc → bcc. Such a transition (fcc → ω + bcc transition) can be confirmed by Widmanstätten pattern formed in an iron meteorite, pearlitic structure and martensite composed of bcc-ferrite and ultra-fine ω particles in iron-carbon steels. The present fcc-bcc orientation relationship matches with Pitsch’s one.     

Extraction and separation of Ga(Ⅲ) and TI(I) or In(Ⅲ) and TI(I) from chloride media with CA-12 in sulphonating kerosene

The extractjon behavior and mechanism of gallium(Ⅲ)and thallium(Ⅰ)or indium(Ⅲ)and thallium(Ⅰ)with Sec-octylphenoxy acetic acid(CA-12)from hydrochloric acid solution in sulphonating kerosene were studied.Optimum extracuon conditions were evfluatedfrom critical study of various experimental parameters andthe probable composition of the extracted species is ascertainedfromlg D-lg C plots.The effects of differentions on the determination of these ions were examined.     

Molybdate/Al(III) composite films on steel and zinc-plated steel by chemical conversion

A molybdate(VI)-Al(III) chemical conversion process was developed as an alternative to the chromate processes. Steel and zinc-plated steel specimens were treated in the solutions of 0.16 mol l⁻¹ ammonium alum (AlNH₄(SO₄)₂ · 12H₂O) with small amounts of ammonium molybdate(VI) (0.002-0.016 mol l⁻¹ (NH₄)₆Mo₇O₂₄ · 4H₂O) at 60 °C for 10-30 min in an ultrasonic rinsing apparatus. The formed films were composed of oxyhydroxides containing Mo(V,VI), Al(III), Fe(II,III), and sulfate ions (and Zn(II) ions in the case of zinc-plated steel), and showed good corrosion resistance in an aerated 0.5 mol l⁻¹ NaCl-0.15 mol l⁻¹ H₃BO₃ solution (pH=7). The films macerated during the corrosion test, but they did not detach and functioned as a protective layer. This process may be useful in forming undercoats for paints and polymer coatings on steel and zinc-plated steel.     

面向等离子体W材料改善韧性的方法与机制

目的: 探讨胰岛素样生长因子1（IGF-1）基因多态性与抗高血压药物治疗后血压水平的关联性。方法: 运用流行病学现况调查方法,收集服用复方利血平、降压片和珍菊降压片的780例高血压患者的一般临床特征并测量其血压和临床生化指标。选择IGF-1基因的5个标签位点,采用TaqMan技术进行基因分型。采用协方差分析及分层分析对其基因多态性与药物治疗后血压水平的关系进行评价。结果: 在服用降压片的高血压病人中,rs6219位点不同基因型之间舒张压水平差异有统计学意义（P=0.01）。在服用复方利血平的高血压病人中,rs5742612和rs6218位点不同基因型之间收缩压水平差异有统计学意义（P值分别为0.04、0.017）。在服用珍菊降压片的高血压患者中,rs6218位点不同基因型之间舒张压水平及rs6219位点不同基因型之间收缩压水平差异均有关联（P值分别为0.017、0.033）。进一步分层分析发现,服用降压片的患者中,随着rs35767位点遗传变异女性收缩压的水平呈线性下降,而男性舒张压水平呈线性上升,校正混杂因素后P值分别为0.028、0.038。结论: IGF-1基因多态性与复方利血平、降压片和珍菊降压片三种抗高血压药物治疗后血压水平均有显著相关,提示IGF-1基因可能是高血压重要的药物疗效生物标记。     

Ti(C,N)复合膜和TiN/Ti(C,N)多层膜组织和显微硬度

采用非平衡反应磁控溅射的方法在Si(100)基片上沉积Ti(C,N)复合膜和不同调制周期、调制比的TiN/Ti(C,N)纳米多层薄膜。薄膜的微观结构和力学性能采用X射线衍射仪(XRD)、显微硬度计进行表征。结果表明,Ti(C,N)复合膜的微观结构和力学性能与掺入C的含量有关;TiN/Ti(C,N)纳米多层膜的微观结构和力学性能与调制周期和调制比有关,其显微硬度在一定的调制周期和调制比范围内出现了超硬现象。Ti(C,N)、TiN/Ti(C,N)均为δ-NaCl面心立方结构;Ti(C,N)复合膜显微硬度提高是因为固溶强化,TiN/Ti(C,N)纳米多层膜硬度的提高主要是共格外延生长在界面处产生的交变应力场。     

Comparison of the spectroscopic behaviour of single crystals of lanthanide halides (X = Cl, Br)

Halides belong to large band gap matrices that have the perspective of wide applications when doped by optical active ions. This paper presents the results of spectroscopic studies of single crystals of halides (Cl, Br) of Ce, Pr and Nd. Their spectroscopic behaviour: electron–phonon coupling, ion pair interactions and the effect of covalency, is compared. Absorption, emission and emission excitation spectra of single crystals of LnCl₃·yH₂O (Ln = Nd, Pr, Ce; y=6, 7) were recorded at room temperatures and low temperatures down to 4.2 K. The intensities of the electronic lines and the Judd–Ofelt parameters were calculated (Nd, Pr) and compared to those of LnBr₃·yH₂O presented earlier by us. The relationship between the hypersensitivity and covalency was discussed. With increasing soft character of the halides (Br⁻ > Cl⁻), the covalent character of Ln–ligand bond increases and the hypersensitive bands become more intense. The Judd–Ofelt intensity analysis resulted in a set of τ_λ parameters evaluated with quite low standard deviations. The temperature dependences of the intensities have been found and the vibronic coupling in the f–f transitions were analysed. At the low temperature (4.2 K), strong vibronic components occur in the electronic lines of the Nd(III) and Pr(III) ions, mainly with the Ln–X vibrations. The modes, which are in resonance with the splitting of the ground state multiplet, mediate in the cooperative transitions.

Vibrational studies of the compounds under test were performed at the ambient temperature using IR and Raman spectroscopy. The assignment of the bands was done on the basis of the factor group analysis. The spectral features below 300 cm⁻¹ point at the differences between the spectra of the bromides and chlorides of Nd and Pr. Although the spectral features within the FIR region are complex, the bands of the praseodymium monocrystals originated by halogen bridges are clearly visible.     

Manufacturing of high performance solid oxide fuel cells (SOFCs) with atmospheric plasma spraying (APS)

The potential of atmospheric plasma spraying (APS) technology has been investigated for the manufacture of anode, electrolyte and cathode of a solid oxide fuel cell. As the substrate a tape-casted FeCr alloy was used. It turned out that all layers can be applied by this technique, however, the APS cathode layer, although applied by suspension plasma spraying led to cells with rather low performance. Much better cell characteristics could be obtained by using screen-printed LSCF cathodes, which do not need any additional thermal treatment.Anode layers with high electrochemical activity were produced by separate injection of NiO and YSZ powders. The manufacturing of gastight electrolyte layers was a key-issue of the present development. As APS ceramic coatings typically contain microcracks and pores their leakage rate is not sufficiently low for SOFC applications.Based on the understanding of the formation of defects during spraying an optimized spraying process was developed which led to highly dense coatings with the appearance of a bulk, sintered ceramic. Open cell voltages above 1 V proofed the low leakage rates of the rather thin (< 50 μm) coatings. With these cells having a screen-printed cathode an output power of 500 mW/cm² could be achieved at 800 °C.It turned out that the long-term stability of the metal substrate based APS SOFCs was rather poor. The aging of the cells was probably due to interdiffusion of anode and substrate material. Hence, diffusion barrier was applied by APS between substrate and anode. These layers were very effective in reducing the degradation rate. For these cells the output power reached 800 mW/cm².