BRITTLE-DUCTILE TRANSITION OF ANNEALEMBRITTLED Fe_(75)Si_(10)B_(15)METALLIC GLASS

Studies were made of the effect of mechanical pulverization on relaxation,crystallizationand brittle-ductile transition of the anneal-embrittled Fe_(75)Si_(10)B_(15) metallic glass rib-bon.Results show that the Curie temperature,T_C,decreases and the total enthalpy ofrelaxation increases gradually with variation of pulverized time.DSC traces reveal anextra exothermic peak,T_X_1,and a distinct glass transition endothermic peak,T_g_1,withincreasing pulverized time,T_C,T_X_1,and T_g_1 decrease simultaneously,and the exother-mic peak area corresponding to T_X_1 increases gradually.The surface slip-steps of flakyparticles and their corresponding shear are produced by pulverizing the pre-embrittledamorphous glass.The lost ductility of the glass may restore during annealing.     

INFLUENCE OF RARE-EARTH ELEMENTS ON THERMAL STABILITY OF PdSi_(16.5)GLASS

The influence of rare-earth elements,La,Ce,Pr,Nd,Sm,Eu,Gd,Dy,Ho,Er and Yb onthe thermal stability of PdSi_(16.5) glass was studied systematically by means of DSC.Allrare-earth elements,especially heavy ones,increase obviously the thermal stabilityparameters,including T_θ(T_g ,T_x ,T_g),T_(rg) and ΔE etc.The crystallization temperaturesT_(p1) and T_(p2) increase linearly with the lanthanide constriction increasing,but Eu shows ananomalous influence:Pd-Si-Eu metallic glass possesses the highest thermal stability and thelowest concentration limit of glass forming among Pd-Si-R glasses.     

INFLUENCE OF BORON ON MICROSTRUCTURE AND MECHANICAL PROPERTIES OF RAPIDLY SOLIDIFIED Ni_3Al

By means of nonstoichiometry,rapid solidification and adequate boron addition,the tensilestrength and bending resistance of Ni_3Al has been improved.When adding 0.52 to 1.37 at.-%B into Ni_3Al,which has the beneficial effect on the ductility.If boron addition is too high,there are coarse Ni_(23)B_6 particles and NiB_(12) phases found at the grain boundaries.Boronmodification in Ni_3Al promotes the ordering in the region near grain boundaries.The grainboundary of boron free Ni_3Al is a large angle one,but turns into a small angle grain bound-ary with sub-grains of dislocation characteristics when the boron content in Ni_3Al reaches1.37 at.-%.     

Fe_8Ni_(27)Co_(43)Si_8B_(14)金属玻璃的磁稳定性

在直到300℃的范围内考查了 Fe_8Ni_(27)Co_(43)Si_8B_(14)金属玻璃的磁导率弛豫。估计了弛豫过程的激活能谱。证实了时效引起的磁导率衰减是可逆的结构重排过程。观察到磁导率衰减中的 cross-over 效应。定量地估计了较低温度下的磁稳定性。     

MSSBAUER STUDY ON MAGNETIC ANISOTROPY OF AMORPHOUS ALLOY Fe_(71)Ni_(10)B_(13)Si_4C_2

本文研究了Fe_(71)Ni_(10)B_(13)Si_4C_2非晶态合金在磁场退火时的反常磁各向异性变化。结果表明,在430℃磁场热处理时优先发生了表面晶化现象,导致垂直磁各向异性的反常增大。磁矩取向的择优性取决于压应力引起的和磁场热处理感生的两种磁各向异性。     

INFLUENCE OF THE ALIGNMENT OF TiO_2 NANOPARTICLES ON OPTICAL AND STRUCTURAL PROPERTIES OF POLY(PHENYLENEVINYLENE) FILMS

A series of poly(phenylenevinylene) (PPV)/titanium oxide (TiO2) nanocomposites with different contents of TiO2 nanoparticles were prepared from mixtures of PPV precursor and titanium butoxide ethanol solution in a sol-gel process. TEM images showed the formation of the connected network of TiO2 nanoparticles with a higher content of TiO2, which resulted in the titanium butoxide hydrolyzed to form Ti organic compound. Meanwhile, the conjugation of PPV polymer chains can be interrupted by the TiO2 network structure. The PL spectra revealed that the emitted light of the PPV/TiO2 nanocomposites blue shifted without fine structure and the PL intensity enhanced when the TiO2 network formed. In the lifetime spectroscopy of positron annihilation, the structural properties of the PPV dominated the character of the nanocomposites, in which the formation of the o-Ps was presented in free volume pf polymer, when the content of TiO2 was below 10%. Further increasing the content of TiO2     

INFLUENCE OF SURFACE MODIFICATION OF Ti BY FLUORINE ION-IMPLANTATION ON FORMATION AND EXPRESSION OF COLLAGEN-I ON OSTEOBLAST

应用等离子体浸没离子注入装置对纯Ti表面进行氟离子注入, 通过SEM和XPS分析研究材料的表面形貌和化学组成. 将MG-63成骨细胞接种于氟离子注入前、后的 Ti样品表面, 采用激光共聚焦显微镜观察材料表面对成骨样细胞MG-63 I型胶原形成的影响; 逆转录聚合酶链反应检测I型胶原mRNA的表达; 蛋白印迹法检测I型胶原蛋白的表达. 结果表明, 氟离子注入后Ti样品表面新出现TiF3; 且MG-63细胞在其表面分别培养6, 24和48 h后, I型胶原的形成和表达均明显高于纯Ti表面. 含氟表面改性层可提高Ti材料的生物相容性.     

STRUCTURE AND GLASS FORMING ABILITY(GFA)OF AMORPHOUS ALLOYS

A new microstructure model is developed for amorphous alloys,so called Cluster medel,in which the amorphous phase is thought of composing of randomly distributed orderedclusters of different sizes.Thermodynamic calculation on this model deduces a parameterdescribing the glass forming ability of metallic alloys:α_c=(1-2.08/Φ_m)T_g/T_m,whereT_g is gass transition temperature,T_m is the melting temperature,and Φ_m is entralpychange of melting.It is believed that easy glass forming alloy systems have larger valuesof a_c.This new criterion of GFA not only provides the theoretical background for severalGFA criteria in the literature cited,but also can predict the GFA of many alloy systemsmore reasonably and accurately.     

INFLUENCE OF PULSED MAGNETIC FIELD ON MICROSTRUC-TURES AND MACRO-SEGREGATION IN 2124 Al-ALLOY

The structures and macro-segregation of 2124 Al-alloy were studied when a pulsedmagnetic field (PMF) was applied during solidification. It is found through experi-ments that a remarkable change occurs in the solidification structures of 2124 Al-alloyunder pulsed magnetic field. The eutectic phase at grain boundaries change from thickcontinuous eutectic network to thin discontinuous one, and the distribution of soluteelements was also homogenized. The typical negative segregation phenomenon of Cu incommon solidification condition was restrained, and the segregation of Mg decreased.     

净化对非晶形成能力和非晶热稳定性的影响SCIEI

采用玻璃熔体净化法和电磁悬浮循环过热法消除Ni_(75),B_(17)Si_R合金液内的异质核心,研究了净化对该合金液非晶形成能力和所形成的非晶合金热稳定性的影响。采用净化和忽冷相结合的工艺制备出了20×10×0.5mm的Ni_(75)B_(17)Si_8非晶试样,试样的厚度较净化前提高了4倍。     

退火变脆Fe75Si10B15金属玻璃的脆韧性转变

研究了机械研磨对退火变脆Fe_(75)Si_(10)B_(15)金属玻璃的弛豫过程,晶化行为及脆韧性转变的影响。发现退火变脆的Fe_(75)Si_(10)B_(15)金属玻璃,经不同时间机械研磨,Curie温度T_C逐渐回落,总的弛像焓ΔH_?逐渐回升。在DSC曲线上观察到明显的玻璃转变温度T_(g_1)和一个附加的宽放热峰T_(x_1),随着研磨时间的增加,T_(x_1),T_(x_1),T_C同步降低,与T_(x_1)对应的放热面积ΔH_(x_1)逐渐增大,并在片状粒子表面形成切变带以及与其对应的剪切带,玻璃在退火过程中失掉的韧性逐渐得到恢复。     

深过冷合金再辉与凝固组织的研究

发现深过冷Ni_(68)B_(21)Si_(11)合金液形核过程中的多次再辉现象,揭示了二次和三次再辉的过冷条件,以及对凝固组织的影响。研究结果表明,深过冷Ni_(68)B_(21)Si_(11)合金液存在两种凝固机制:一是NilB,Nj‘si,B和Ni,B的三相共晶生长;另一个是以NilB为领先相的枝晶簇生长。当过冷度低于200K或超过310K时,合金液凝固仅伴生一次再辉,其晶体生长以第一种凝固方式进行。其他过冷范围内的合金液则发生多次再辉和枝晶簇凝固。     

HEAT CAPACITIES OF Fe_（40）Ni_（40）B_（20） GLASSY ALLOY MEASURED BY ENTHALPY METHOD

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制备条件对非晶态Fe78B13Si9合金的热膨胀各向异性的影响

本文研究了不同条件下形成的非易态Fe_(78)B_(13)Si_9合金在长轴和短轴方向上的热膨胀。结果表明,在所有条件下均存在热膨胀的各向异性。热膨胀系数随着冷却速度的增加而增加,但其各向异性减小;随着熔体喷铸温度的提高两者均减小。在热循环的作用下,短轴方向的热膨胀系数及其各向异性均减小;而在长轴方向的热膨胀系数却增大。我们认为热膨胀各向异性来源于原子交互作用力的方向性、原子振动频率和短程有序结构或缺陷的方向性。     

EFFECT OF PREPARATION CONDITION ON THERMAL EXPANSION ANISOTROPY FOR AMORPHOUS Fe_(78)B_(13)Si_9 ALLOY

The thermal expansion along the longitudinal and transverse directions for amorphousFe_(78)B_(13)Si_9 alloy prepared under various preparing conditions were investigated.The thermalexpansion anisotropy appears in all specimens.The expansion along the longitudinal directionis less than that along the transverse direction.The cooling rate,the melt temperature beforejet casting and the cycling temperature affect the thermal expansion coefficients andanisotropy.The amisotropy of thermal expansion originates from the orientation of atomicinteraction force,the atomic oscillatory frequency and short range order structure or thedirectional arrangement of defects in the alloy.     

Fe78B13Si9纳米晶合金的热性能研究

采用适当的热处理工艺将相同成分的Fe_(78)B_(13)Si_9非晶态合金条带晶化制备成纳米晶合金;测定并研究了纳米晶合金的微观结构(晶体结构及尺寸)和一些结构敏感性能(热膨胀、比热),同时,将其与同样成分的非晶态、大晶粒状态合金的性能进行比较分析,认为由于纳米晶合金特殊的微观结构(短程无序),使其在性能上表现出与通常材料有很大差异。     

Microscopic phase-field study on aging behavior of Ni_(75)Al_(17)Zn_8 alloy

The precipitating kinetics of Ni75Al17Zn8 alloy was studied at both 873K and 973K by microscopic phase-field model.The calculation results show that the order-disorder transformation experiences the matrix→lowly-ordered L10 phase→L12 phase at 973 K.And the nucleation of L12 particles belongs to the spinodal decomposition mechanism.As temperature increases,orderings of Al and Zn atoms are resisted,but coarsening of L12 particles is promoted.The value of coarsening kinetic exponents approaches to 1/2.In addition,the discussions about Ni-Al anti-site defect and Zn substitutions for Ni site and Al site exhibit that the higher the temperature,the more distinctive the Ni-Al anti-site defect,but the less the Zn substitution.