Crystallization kinetics of the pure triacylglycerols glycerol-1,3-dipalmitate-2-oleate,glycerol-1-palmitate-2-oleate-3-stearate,and glycerol-1,3-distearate-2-oleate

Crystallization kinetics of the three main components of cocoa butter, the triacylglycerols POP, POS, and SOS (where P, O, and S stand for palmitic, oleic, and stearic acids, respectively) were studied by combined differential scanning calorimetry and polarized light microscopy. The morphologies, nucleation kinetics, growth kinetics, and phases of the grains formed were identified with this system. The experimental data, as well as two different models to simulate crystallization and to predict behavior of the pure triacylglycerols, are presented. The first model is based on a macroscopical approach to solidification by using time-temperature-transformation (TTT) diagrams and the additivity principle. It allows prediction of the proportion of the different phases formed for any given thermal path imposed on the sample once the TTT diagram is known for the product. It is illustrated for SOS at constant cooling rates and is compared with experimental results. The second model directly simulates growth of the spherulites in the sample by using nucleation and growth rates that are determined experimentally. It provides a view of the structure as it would be observed with a microscope and shows evolution of the heat released in the sample. Isothermal solidification of POP at 15°C is displayed. The experiment and the model are in good agreement.     

等温马氏体转变动力学模型的修正

自促发形核机制对于等温马氏体转变的解释是正确的.但是现有几种动力学模型尚存在一些不妥之处.文中给出一种物理意义更为明确的修正模型.     

崩岸治理试验工程模袋固化砂浆的研究与应用

通过水泥基高掺量粉煤灰及外加剂对粉细砂进行固化研究，拟寻求一种既有一定的强度，又有较好的施工性能，而且成本又比较低的模袋充灌材料－－模袋固化砂浆，并对其长龄期力学性能进行试验研究。该材料在九江江新洲崩岸治理试验工程中得到实际应用，取得了较好的效果。     

Microstructural Evolution of Rapidly Solidified Co-Mo and Ni-Mo Eutectic Alloys

Droplets of Co-37.6 wt pct Mo and Ni-47.7 wt pct Mo eutectic alloys were rapidly solidified during containerless processing in a 3 m drop tube. A kind of anomalous eutectic appears in these two eutectic alloys when undercooling is beyond 56 and 61 K, respectively. The two eutectic phases in anomalous eutectic were observed to grow in dendrite manner. The formation of anomalous eutectic is ascribed to the cooperative dendrite growth of the two independently nucleated eutectic phases. Current dendrite and eutectic growth theories are applied to describe the observed processes.     

SHS quenching as a route to bulk glassy Fe<Subscript>34</Subscript>Co<Subscript>34</Subscript>B<Subscript>10</Subscript>Si<Subscript>14</Subscript>Nb<Subscript>8</Subscript> alloys

The method of SHS quenching combined with dynamic annealing was used to prepare bulk amorphous metallic glass alloys Fe₃₄Co₃₄B₁₀Si₁₄Nb₈ in a two-stage process. The structural properties and microstructure of thus prepared materials were found to be close to those produced by other methods, such as melting-injection-molding and melt spinning.      

方坯连铸过程中钢液流动、凝固及溶质分布的耦合数值模拟

采用Fe-C二元合金的连续介质模型，对方坯连铸过程进行紊流动，凝固及溶质传输的三维耦合数值模拟，计算表明，注流在结晶器上部形成的回,大部分返回主入流股，其余部分随凝固坯壳向下流动，凝固坯壳在截面上由于注流冲刷造成不均匀分布，与实际情况相符，随凝固进行，液相中的溶质不断富集，最终在铸坯中心区域形成宏观偏析。     

一次枝晶间距模型及在单晶高温合金中的验证(英文)

本文评述了二元系统一次枝晶间距模型的发展及特点,并验证了在多元合金系统中的适用性,结果表明,在 DD8单晶高温合金中,λ_1-G 关系符合二元系统模型,但λ_1-V 关系和二元系统模型有较大的偏离,λ_1为一次枝晶间距,G 为温度梯度,V为凝固速率。在本文凝固条件下,DD8合金的λ_1-G,V关系式为:λ_1=1141.5G~(-0.52)V~(-0.12),其中λ_1单位为μm,G 为 K/mm,V为μm/s。     

Oxidation behavior of Ni2Al-0.1B containing 2Cr

Ni ₃ Al-0.1B containing 2% Cr was subjected to a thermal cycling oxidation test in pure flowing oxygen at atmospheric pressure at temperatures cycled between 400 and 1300 K. Scales formed on the alloy spalled repeatedly after several tens of cycles, resulting in a considerable mass loss of mass of the specimen. The isothermal oxidation behavior of the alloy was also studied at temperatures of 1300, 1400, and 1500 K in the same oxidizing atmosphere. Characteristic breakaway oxidation caused by extensive scale blistering was observed at 1300 and 1400 K after a protective period of about 50 ksec, whereas the oxidation at 1500 K followed a parabolic law without any significant blistering. Particularly at 1300 K, the alloy grain boundaries provided favorable sites for blistering. The influence of Cr may be explained by the modification of mechanical property of the scale.     

Processing Effects on the Engineering Properties of Cast Metal-Matrix Composites

The physical and mechanical properties of metal-matrix composites synthesized using the various solidification and casting techniques are reviewed. The emphasis is on engineering properties such as strength, ductility, fracture toughness, hardness, creep, wear and friction, damping, and thermal and electrical properties. The process-structure-property relationships for these materials are highlighted with specific examples from composites of practical importance. It is shown that as both the structure and properties of cast composites are extremely sensitive to a myriad of process-related variables (temperature, time, atmosphere, pressure etc.), the composite performance must be evaluated in synergy with the fabrication technique in order to establish a rigorous protocol between composite performance and fabrication techniques.     

两向热流对钢锭凝固过程中流动作用的模拟研究

系统考察了两向热流条件下网锭凝固过程中流动的以及流场和温度场的相互作用。结果表明，当流动方向和等温线推进方向一致时，流动强化了等温线的推进，当流动方向和等温线推进方向相反射，流动削弱了等温线的推进。顶部冷却容易引起热扰动，使得对流过程不稳定，底部冷却加快了底部等温线的推进，稳定了对流过程，减少了流速。