Structure and superconducting properties of Ru_(1-x)Mo_(x)(x=0.1-0.9)alloys

We report the detailed crystal structures and physical properties of Ru_(1-x)Mo_(x)alloys in the solid solution range of x=0.1-0.9.Structure characterizations indicate that the crystal structure changes from the hcp-Mg-type,toβ-CrFe-type,and then bcc-W-type.The measurements of physical properties show that the Ru_(1-x)Mo_(x)samples with x≥0.2are superconductors and the superconducting transition temperature T_c as a function of Mo content exhibits a dome-like behavior.

211Z.1铝合金微观组织及力学性能研究

主要对211Z.1铝合金材料进行了金属型铸造加工及力学性能测试。实验结果显示,制备出的铸造试棒表面光滑,无铸造缺陷。经过T5热处理工艺之后,其平均抗拉强度达到了349.8 MPa,断后延伸率为21.3%,布氏硬度100,展现出优良的力学性能。通过光学显微镜(OM)、扫描电子显微镜(SEM)等技术手段,实施了对合金微观结构的深入分析,探索了微观组织对合金力学性能的影响,并揭示了其性能的内在联系。本研究结果为211Z.1铝合金在工程领域的应用以及未来材料设计方面提供了理论探索和实践指引。

Simulation on function mechanism of T1(Al_2CuLi) precipitate in localized corrosion of Al-Cu-Li alloys

To clarify the corrosion mechanism associated with the precipitate of T1(Al2CuLi)in Al-Li alloys,the simulated bulk precipitate of T1 was fabricated through melting and casting.Its electrochemical behavior and coupling behavior with α(Al)in 3.5% NaCl solution were investigated.Meanwhile,the simulated Al alloy containing T1 particle was prepared and its corrosion morphology was observed.The results show that there exists a dynamic conversion corrosion mechanism associated with the precipitate of T1.At the beginning,the precipitate of T1 is anodic to the alloy base and corrosion occurs on its surface.However,during its corrosion process,its potential moves to a positive direction with immersion time increasing,due to the preferential dissolution of Li and the enrichment of Cu.As a result,the corroded T1 becomes cathodic to the alloy base at a later stage,leading to the anodic dissolution and corrosion of the alloy base at its adjacent periphery.It is suggested that the localized corrosion associated with the precipitate of T1 in Al-Li alloys is caused by the alternate anodic dissolution of the T1 precipitate and the alloy base at its adjacent periphery.

Effect of ageing temperature on precipitation of A1-Cu-Li-Mn-Zr alloy

The precipitation behaviors of an A1-Cu-Li-Mn-Zr alloy at different ageing temperatures （120, 160 and 200 ~C） were investigated using Vickers hardness measurements and transmission electron microscopy （TEM） characterization. Age hardening curves show an increase in precipitation kinetics with increasing ageing temperature. The results of TEM show that for the samples peak aged at 120 ~C, the amount of g＇ （A13Li）, GP zones/0＇ （A12Cu） and Z （A15Cu6Li2） phases is obviously higher than that of T1 （A12CuLi） precipitates; while the samples peak aged at 160 and 200 ~C are usually dominated by T1 phase with a minor fraction of GP zones/0＇ and g＇, and the Z phase almost does not form. In addition, quantitative analysis on the T1 platelets demonstrates that the samples peak aged at 200 ~C have larger plate diameter and smaller area fraction of T1, as compared to the samples peak aged at 160 ~C. Correspondingly, the possible reasons for such phenomena are discussed.

薄片状PtZn@Silicalite-1分子筛的合成及催化丙烷脱氢性能研究

采用水热晶化法,以四甲基胍(TMG)为形貌调控剂,一步合成封装PtZn纳米合金的薄片状Silicalite-1分子筛(PtZn@Silicalite-1)。采用X射线衍射(XRD)、透射电子显微镜(TEM)、X射线光电子能谱(XPS)等技术对样品进行表征分析,并考察了其丙烷脱氢催化性能。结果显示,加入TMG可有效调控Silicalite-1分子筛晶体的生长取向,晶体沿b轴的尺寸与TMG/SiO_(2)的比值呈反比。在550℃和纯丙烷气氛下,片状PtZn@Silicalite-1催化剂表现出优异的丙烷脱氢性能,经过20 h的连续反应,其失活常数仅为0.007 h^(-1),而常规PtZn@Silicalite-1催化剂为0.013 h^(-1)。结合表征结果,薄片状分子筛催化剂具有更大的外比表面积和更短的b轴直通道,这提高了脱氢活性位的可接近性,缩短了气体分子在孔道中的扩散路径,从而提升了催化剂的活性和稳定性。

ZSnSb11-6巴氏合金与ZQSn10-1锡青铜耐磨性对比研究

采用MFT-5000型摩擦磨损试验机,对比研究了ZSnSb11-6巴氏合金和ZQSn10-1锡青铜在不同载荷下的耐磨性。结果表明:当载荷为20 N时,锡青铜的磨损率较巴氏合金低78.3%,当载荷为140 N时,锡青铜的磨损率较巴氏合金仍低36.3%;ZSnSb11-6巴氏合金由于硬度较低,磨痕和犁沟较深,同时随着载荷的增加,易在硬质相β相(SnSb)处发生剥落;ZQSn10-1锡青铜由于硬度较高,磨痕和犁沟较浅,同时由于(α+δ)硬质相的尺寸较小,无尖锐的棱角,剥落程度轻。因此,在20~140 N载荷下ZQSn10-1锡青铜的耐磨性优于ZSnSb11-6巴氏合金。

Al-Cr-Fe-Mn-Ni高熵合金中的L2_(1)相的相稳定性及其性能研究

为开发兼具良好强度与塑性的BCC基高熵合金,可引入与基体共格的B2或L2_(1)相。L2_(1)相具有更好的抗蠕变性能,有望在高温环境中得到应用。但是,目前对BCC型高熵合金中L2_(1)相的存在规律、相稳定性及其对合金性能的影响还缺乏深入的研究。为此,本工作研究了电弧熔炼制备的铸态Al_(0.5)Cr_(2.5-x)FeMn_(x)Ni(x=0.5~1.75)、Al_(0.75)Cr_(2.25-y)FeMn_(y)Ni(y=0.25~1.5)、AlCr_(2-z)FeMn_(z)Ni(z=0.5~1.5)高熵合金的相组成,及800℃或1000℃真空退火120 h对合金组织和相组成的影响。研究表明,这些合金中L2_(1)相的成分特征由40%~50%(原子分数)Ni和15%~20%(原子分数)Al、Mn组成。L2_(1)相只存在于Al含量为10%~15%(原子分数)的合金中,且多以BCC+L2_(1)两相共存,获得的组织为编织网状的调幅分解组织。当Al含量达到20%(原子分数)后,合金则由BCC+B2两相构成。L2_(1)相的存在会使BCC型XRD特征峰出现明显的峰分裂。经过800℃或1000℃退火后,合金中L2_(1)相仍能稳定存在,合金显微组织发生粗化并会形成σ或FCC相。铸态合金的硬度随Mn含量的增加而降低,含L2_(1)相的合金的硬度在463HV~558HV范围内。800℃退火会使含5%~15%(原子分数)Mn的合金硬度降低70HV~100HV,但由于硬质σ相的析出,含20%~30%(原子分数)Mn的合金硬度提高200HV以上;1000℃退火后,由于软质FCC相的形成,合金的硬度略有降低,这些结果将为BCC型高熵合金的设计奠定基础。

轧制应变速率对Mg-1%Al合金组织、阻尼和力学性能的影响

在不同应变速率下轧制Mg-1%Al合金板材,研究了轧制应变速率对Mg-1%Al合金显微组织、力学性能和阻尼性能的影响。随着轧制应变速率增加,Mg-1%Al合金的平均晶粒尺寸和再结晶体积分数增加;抗拉强度、屈服强度和织构强度减小;延伸率先升高后降低,在应变速率20 s^(-1)时达到最高,为25.33%。随着应变速率增加,室温阻尼性能增加,应变速率30 s^(-1)下应变振幅0.1%时阻尼值为0.061,是应变速率15 s^(-1)时的1.5倍。应变速率一定时,阻尼性能随着频率增加而降低。

Improved Corrosion Behavior of Biodegradable Mg-4Zn-1Mn Alloy Modified by Sr/F co-doped CaP Micro-arc Oxidation Coatings

The Sr/F co-doped CaP(Sr/F-CaP)coatings were prepared by micro-arc oxidation(MAO)under different voltages to modify the microstructure and corrosion behavior of Mg-4Zn-1Mn alloy.The surface and interface characteristics investigated using scanning electron microscopy(SEM)and energy dispersive X-ray spectrometer(EDS)showed that the MAO coatings displayed uneven crater-like holes and tiny cracks under lower voltage,while they exhibited relatively homogeneous crater-like holes without cracks under higher voltage.The thickness of MAO coatings increased with increasing voltage.The corrosion behavior of Mg-4Zn-1Mn alloy was improved by the MAO coatings.The MAO coatings prepared under 450 V and 500 V voltages possessed the best corrosion resistance with regard to the electrochemical corrosion tests and immersion corrosion tests,respectively.The MAO coatings fabricated under 450-500 V could provide a better corrosion protection effect for the substrate.

Behavior of Growth and Coarsening of T_1(Al_2CuLi) Precipitates in Al-Li Alloys 2090 and 2090+Ce

The behavior of growth and coarsening of T-1(Al2CuLi) precipitates was comparatively studied by means of TEM technique in two Al-Li alloys 2090 and 2090+Ce (with cerium content less than 0.1% in mass fraction). Statistical analysis results show that T-1 precipitates in alloy 2090+Ce have smaller aspect ratio, which is connected with the more intersections between different T-1 variants in this alloy. It is also found that the variation of maximum length of T-1 precipitates with aging time can be obviously divided into two stages of growth and coarsening. The diffusion coefficients of solute atoms of Cu and Li are calculated via growth kinetics curves of T-1 precipitates. The results show that the diffusion of atom Cu plays a more important role in the formation of T-1 precipitates.

BFe10-1-1合金K-TIG焊接接头的组织和性能

采用Keyhole TIG(K-TIG)焊接工艺开展了10 mm厚BFe10-1-1铜合金板的焊接试验。结果表明:采用K-TIG焊实现了单面焊双面成型,焊缝成型美观,接头焊缝截面无气孔、未熔合、裂纹等缺陷;焊缝区主要为枝晶状α组织,由熔合线向焊缝中心生长延伸;母材区和热影响区的组织是孪晶状的α相,且热影响区距离焊缝越近,其晶粒尺寸越大。焊缝区的硬度值较高,从焊缝到母材的硬度值先降低再增加,近熔合线的焊缝区和打底焊缝上部区域出现轻微软化。接头平均抗拉强度为346.5 MPa,断裂位置为母材;在α=180°、d=4 t条件下进行侧弯测试,未发现裂纹。

Comparative study on the hydrogen storage performance of as-milled MgRENi rapid quenched alloy catalyzed by metal sulfides

The composites of Mg_(20)Pr_(1)Sm_(3)Y_(1)Ni_(10)as-quenched alloy and 3 wt.%M(M=CoS,CoS_(2),MoS_(2))catalyst were prepared by high-speed vibration ball mill.The effects of metal sulfides on the hydrogenation and dehydrogenation dynamics of alloys were compared.The results show that the as-milled composites contain a large number of amorphous embedded by a small amount of nanocrystals,and there are many point defects.After ball milling,the crystal grain size in the composites containing CoS is relatively larger,followed by CoS_(2)and MoS_(2)again.After hydrogenation,the amorphous phase is crystallized to form Mg_(2)NiH_(4),YH_(3),Pr_(8)H_(18.96),Sm_(3)H_7,Mg,Co or Mo phases,however,Mg_(2)Ni,YH_(2),PrH_(2)and Ni_(3)Y phases appeared after dehydrogenation.The maximum hydrogenation capacity of the composites containing CoS,CoS_(2)and MoS_(2)are 3.939,4.265 and 4.507 wt.%,respectively.The hydrogenation saturation ratio of composite containing MoS_(2)is higher than that of the composites containing CoS and CoS_(2).The dehydrogenation activation energy of the composites containing CoS,CoS_(2)and MoS_(2)is 107.76,68.43 and 63.28 kJ.mol^(-1).H_(2).On the improvement of hydrogen storage performance of Mg_(20)Pr_(1)Sm_(3)Y_(1)Ni_(10)alloy,the catalytic effect of MoS_(2)sulfide is better than that of CoS_(2)sulfide,and which is better than CoS sulfide.

高性能聚丁烯-1/聚丙烯釜内合金管材的结构与性能

采用单螺杆管材挤出机,制备了高等规聚丁烯-1(iPB)与聚丁烯-1/聚丙烯合金(PBA)管材,通过差式扫描量热、小角X射线衍射、耐热蠕变、爆破性能、静液压性能与力学性能测试,考察了iPB与PBA管材的结晶性能与力学性能,PBA管材中PB的片晶厚度,熔融温度与结晶温度均得到提升,耐热蠕变性、爆破与静液压性能、力学性能均优于iPB管材,可作为新一代高性能热水管材使用。

Effects of Ce addition on microstructure and mechanical properties of Mg-6Zn-1Mn alloy

The effects of Ce addition on the microstructure of Mg-6Zn-1Mn alloy during casting, homogenization, hot extrusion, T4, T6 and T4＋two-step aging were investigated. The mechanical properties of alloys with and without Ce were compared. The results showed that Ce had an obvious effect on the microstructure of ZM61-0.5Ce alloy by restricting the occurrence of dynamic recrystallization and restraining the grain growth during extrusion and heat treatment subsequently. A new binary phase Mg 12 Ce was identified in ZM61-0.5Ce alloy, which distributed at grain boundaries and was broken to small particles distributed at grain boundaries along extrusion direction during extrusion. The mechanical properties of as-extruded ZM61-0.5Ce alloy were improved with the addition of Ce. The improved tensile properties of as-extruded ZM61-0.5Ce alloy were due to the finer grain sizes as compared to ZM61 alloy. However, the UTS and YS decreased severely and the elongation increased when ZM61-0.5Ce was treated by T6 and T4＋two-step aging. Brittle Mg 12 Ce phase, which was distributed at the grain boundary areas and cannot dissolve into the Mg matrix after solution treatment, became crack source under tensile stress.

Effects of yttrium and strontium additions on as-cast microstructure of Mg-14Li-1Al alloys

Mg-14Li-1Al （LA141）, LA141-0.3Y, LA141-0.3Sr, and LA141-0.3Y-0.3Sr alloys were prepared in an induction furnace in the argon atmosphere. The microstructures of these alloys were investigated through scanning electron microscope （SEM）, X-ray diffractometer （XRD） and energy dispersive spectrometer （EDS）. The results show that yttrium and/or strontium additions produce a strong grain refining effect in LA141 alloy. The mean grain sizes of the alloys with addition of Y and/or Sr are reduced remarkably from 600 to 500, 260, 230 μm, respectively. Al 2 Y, Al 4 Sr and Mg 17 Sr 2 phases with different morphologies are verified and exist inside the grain or at the grain boundaries, thus possibly act as heterogeneous nucleation sites and pin up grain boundaries, which restrain the grain growth.

Damping properties of as-cast Mg-xLi-1Al alloys with different phase composition

Three kinds of different phases of Mg-xLi-1Al alloys with x=5 （full α LA51）, 9 （dual-phase LA91）, and 14 （rich-βLA141） were prepared by vacuum melting method. Their microstructure and damping capacities were investigated by optical microscopy, X-ray diffractometry, and dynamic mechanical analysis. The results show that the addition of Li changes the crystal structure of the alloys and causes new damping mechanisms to emerge. And the appearance of BCC structure makes the damping performance improved remarkably. The lower the elastic modulus is, the smaller the strain is and even the slower the acceleration is. The dual-phase alloy shows a better damping capacity while the temperature changes. Furthermore, all three alloys have two significant peaks：P1 caused by the movement of dislocations on the basal planes and P2 caused by the sliding of grain boundaries.

Microstructure,mechanical properties and creep resistance of Mg-(8%-12%)Zn-(2%-6%) Al alloys

The microstructural characteristics, mechanical properties and creep resistance of Mg-（8%-12%） Zn-（2%-6%） A1 alloys were investigated to get a better overall understanding of these series alloys. The results indicate that the microstructure of the alloys ZA82, ZA102 and ZA122 with the mass ratio of Zn to A1 of 4-6 is mainly composed of a-Mg matrix and two different morphologies of precipitates （block τ-Mg32（Al, Zn）49 and dense lamellar ε-Mg51Zn20）, the alloys ZA84, ZA104 and ZA124 with the mass ratio of 2-3 contain α-Mg matrix and only block r phases, and the alloys ZA86, ZA106 and ZA126 with the mass ratio of 1-2 consist of a-Mg matrix, block r precipitates, lamellar Ф-Al2Mg5Zn2 eutectics and flocculent β-Mg17Al12 compounds. The alloys studied with the mass ratio of Zn to A1 of 2-3 exhibit high creep resistance, and the alloy ZA124 with the continuous network of r precipitating along grain boundaries shows the highest creep resistance.

Anisotropy of localized corrosion in 7050-T7451 Al alloy thick plate

The corrosion anisotropy of 7050-T7451 A1 alloy thick plate in NaCI solution was investigated by immersion tests, slow strain rate testing （SSRT） technique, potentiodynamic and anode polarization measurements, optical microscropy （OM） and scanning electron microscopy （SEM） observations. The results show that the thick plate exhibits severe corrosion anisotropy due to the microstructure anisotropy. The observations of immersion surfaces together with the analysis of polarization curves reveal that the differences of the corrosion morphologies on various sections in this material are mainly related to the area fraction of the remnant second phase, and higher area fraction displays worst corrosion resistance. The stress corrosion cracking （SCC） susceptibility of different directions relative to the rolling direction is assessed by SSRT technique, ranked in the order： S direction 〉 L direction 〉 T direction. The result show that the smaller the grain aspect ratio, the better the corrosion resistance to SCC.

Effect of heat treatment on microstructures and mechanical properties of sand-cast Mg-4Y-2Nd-1Gd-0.4Zr magnesium alloy

Influence of heat treatment on the microstructures and mechanical properties of sand-cast Mg-4Y-2Nd-1Gd-0.4Zr magnesium alloy was investigated,and the tensile fracture mechanisms of the studied alloys under different conditions were also discussed.The results show that the optimum T4 and T6 heat treatment conditions for the as-cast Mg-4Y-2Nd-1Gd-0.4Zr alloy are 525°C,8 h and（525°C,8 h）＋（225°C,16 h）,respectively,with regard to the microstructure observation,DSC heating curve and mechanical properties.The hardness,yield strength,ultimate tensile strength and elongation of the Mg-4Y-2Nd-1Gd-0.4Zr alloy treated by optimum T6 heat treatment are HV91,180 MPa,297 MPa and 7.4%,respectively.Moreover,the Mg-4Y-2Nd-1Gd-0.4Zr alloys under different heat treatment conditions exhibit different tensile fracture modes.

Microstructure of 18R-type long period ordered structure phase in Mg_(97)Y_2Zn_1 alloy

The microstructure of the 18R-type long period stacking ordered （LPSO） phase in Mg 97 Y 2 Zn 1 alloy was investigated by the first principles calculation. The arrangement rule of Zn and Y atoms in the LPSO structure is determined theoretically. The calculation results reveal that the additive atoms are firstly located in the fault layers at the two ends of the 18R-type LPSO structure, and then extend to fault layers in the interior, which is in good agreement with the experimental observations. This feature also implies the microstructural relationship between 18R and other LPSO structures. The cohesive energy and the formation heat indicate the dependence of the stability of 18R LPSO structure on contents of Y and Zn atoms. The calculated electronic structures reveal the underlying mechanism of microstructure and the stability of 18R LPSO structure.