过共晶Al－Si合金共生区激光表面处理

用２ｋＷ连续ＣＯ２激光对过共晶Ａｌ－１８Ｓｉ合金以不同能量密度和扫描速度进行快速熔凝处理。用扫描电镜、电子微区分析仪分析了微观结构。从计算机对Ａｌ－Ｓｉ合金ｆ－ｎｆ系统的非平衡理论计算所得的共生区及实验结果的分析可见，当能量密度和扫描速度决定的凝固条件处于共生区中部时，过共晶Ａｌ－Ｓｉ合金激光表面处理可以得到共晶间距低于２００ｎｍ的完全共晶结构。     

过共晶铝硅合金细化初晶硅的研究

研究了ZL8604过共晶铝硅合金初晶硅细化剂和加入方式与加入量以及影响细化效果的冶铸工艺因素,实验结果达到了技术指标要求。     

Prediction of evaporation heat transfer coefficient and pressure drop of refrigerant mixtures

A study on the prediction of heat transfer coefficient (HTC) and pressure drop of refrigerant mixtures is reported. HTCs and pressure drops of prospective mixtures to replace R12 and R22 are predicted on the same cooling capacity basis. Results indicate that nucleate boiling is suppressed at qualities greater than 20.0% for all mixtures and evaporation becomes the main heat transfer mechanism. For the same capacity, some mixtures containing R32 and R152a show 8.0–10.0% increase in HTCs. Some mixtures with large volatility difference exhibit as much as 55.0% reduction compared with R12 and R22, caused by mass transfer resistance and property degradation due to mixing (32.0%) and reduced mass flow rates (23.0%). Other mixtures with moderate volatility difference exhibit 20.0–30.0% degradation due mainly to reduced mass flow rates. The overall impact of heat transfer degradation, however, is insignificant if major heat transfer resistance exists in the heat transfer fluid side (air system). If the resistance in the heat transfer fluid side is of the same order of magnitude as that on the refrigerant side (water system), considerable reduction in overall HTC of up to 20% is expected. A study of the effect of uncertainties in transport properties on heat transfer shows that transport properties of liquid affect heat transfer more than other properties. Uncertainty of 10.0% in transport properties causes a change of less than 6% in heat transfer prediction.     

ERD facility for analysis of hydrogen and deuterium in solids

Hydrogen is the lightest element in nature, and so, its detection and quantitative analysis is difficult by the conventional methods utilized for other elements. In the recent years the technique of elastic recoil detection analysis (ERD) using 1–2 MeV He⁺ beam has been developed to quantitatively and simultaneously analyze hydrogen and its isotopes in solids. Such a facility has been set up using the 2 MeV Van-de-Graaff accelerator at IIT Kanpur. It facilitates H and D analysis in a material up to a depth of ∼ 1μm with a detection sensitivity of 0·1 at.% and depth resolution of about 300 ?. The application potential of this setup is illustrated by presenting the results of measurements performed on Al:H:D systems prepared by plasma source ion implantation and highT _c YBCO pellets exposed to humid atmosphere.     

氧化铝丝的研制

氧化铅丝生产过程中最关键的工艺是连续阳极氧化。氧化膜击穿电压决定于氧化膜厚度。控制膜厚度的三要素为:电解液(成份、浓度及温度),槽电压和铝丝走速。     

Electrochemical Investigation on the Formation of Dy-Fe Alloy in Molten Chlorides

ＥｌｅｃｔｒｏｃｈｅｍｉｃａｌＩｎｖｅｓｔｉｇａｔｉｏｎｏｎｔｈｅＦｏｒｍａｔｉｏｎｏｆＤｙＦｅＡｌｏｙｉｎＭｏｌｔｅｎＣｈｌｏｒｉｄｅｓＬｉｕＧｕａｎｋｕｎ（刘冠昆），ＴｏｎｇＹｅｘｉａｎｇ（童叶翔），ＨｏｎｇＨｕｉｃｈａｎ（洪惠婵），Ｙａｎｇ...     

塑料合金用反应型相容剂

反应型相容剂含有反应基团,可与含相应基团的聚合物起化学反应,因而在混炼过程中增容。本文系统地介绍各种反应型相容剂的设计、合成、品种和应用。     

定量电子晶体学硼对Ni3Al的电荷密度分布的影响

阐述了定量电子晶体学测定晶体电荷密度分布的基本原理和方法，不足之处和改善途径。以硼对Ｎｉ３Ａｌ的电荷密度分布的影响为实例，介绍了定量电子晶体学在研究晶体电子结构方面的应用前景。     

GH871 合金的蠕变断裂机制

对采用AIM+ESR和VIM+ESR工艺冶炼的GH871合金在650 ℃的蠕变性能及特征的研究表明,与用AIM+ESR工艺冶炼的GH871合金相比,用VIM+ESR工艺冶炼的GH871合金在蠕变断裂过程中裂纹萌生的形式(包括裂纹形状及形成时间)和裂纹扩展至裂纹连接所需的时间均表现出明显韧化的特征.     

Surface Position-Resolved Thermophysical Properties for Metallic Alloys

Thermophysical properties are collective measures of a material to transport dynamical quantities of physical nature on its surface or through the bulk. As such, the exact nature of couplings between particles in a many-body assembly of building block atoms or molecules sensitively determines their values. The couplings between nearest neighbors are the product of the local elemental composition and the material phase. In this study, thermal cycling of a four-element Wood’s alloy specimen brings out cadmium-rich patches to the top surface of the specimen. An assembly of such patches leads to depth-dependent deviations of elemental composition from that of the bulk. Surface-layer atoms are driven to form a high temperature laser-produced plasma (LPP), and time-resolved spectroscopy of their emissions show the variability of elemental composition over surface positions as well as over depth from the surface. These thermal history-driven composition anomalies contribute to significant variability in the measured values of spectral emissivity and thermal diffusivity.