Synergistic effect of co-alloying elements on site preferences and elastic properties of Ni3Al: A first-principles study

The site preferences of co-alloying elements (Mo–Ta, Mo–Re, Mo–Cr) in Ni₃Al are studied using first-principles calculations, and the effects of these alloying elements on the elastic properties of Ni₃Al are evaluated by elastic property calculations. The results show that the Mo–Ta, Mo–Re and Mo–Cr atom pairs all prefer Al–Al sites and the spatial neighbor relation of substitution sites almost has no influence on the site preference results. Furthermore, the Young's modulus of Ni₃Al increases much higher by substituting Al–Al sites with co-alloying atoms, among which Mo–Re has the best strengthening effect. The enhanced chemical bondings between alloying atoms and their neighbor host atoms are considered to be the main strengthening mechanism of the alloying elements in Ni₃Al.     

Material design and development: From classical thermodynamics to CALPHAD and ICME approaches

This paper presents an overview and examples of material design and development using (1) classical thermodynamics; (2) CALPHAD (calculation of phase diagrams) modeling; and (3) Integrated Computational Materials Engineering (ICME) approaches. Although the examples are given in lightweight aluminum and magnesium alloys for structural applications, the fundamental methodology and modeling principles are applicable to all materials and engineering applications. The examples in this paper have demonstrated the effectiveness and limitations of classical thermodynamics in solving specific problems (such as nucleation during solidification and solid-state precipitation in aluminum alloys). Computational thermodynamics and CALPHAD modeling, when combined with critical experimental validation, have been used to guide the selection and design of new magnesium alloys for elevated-temperature applications. The future of material design and development will be based on a holistic ICME approach. However, key challenges exist in many aspects of ICME framework, such as the lack of diffusion/mobility databases for many materials systems, limitation of current microstructural modeling capability and integration tools for simulation codes of different length scales.     

Alloy optimisation of bainitic steel for large plastic mould

Based on the phase transformation theories, especially the T₀ concept of bainite transformation, alloy optimisation of bainitic steel with carbides has been carried out aiming at the produce of plastic mould with large cross-section. The effect of manganese and silicon on proeutectoid ferrite and bainite transformation is explored by dilatometric analysis, XRD and different microscopy techniques. The results show that after the alloy optimisation, the transformation of proeutectoid ferrite is suppressed and when the cooling rate is lower than 0·1°C?s^??1, the new lower bainite transformation appears by decreasing carbon capacity of austenite and promoting carbide precipitation. Industrial production proves that the optimised alloy SDP1 can meet the demand for the plastic mould with the thickness of 1050?mm.     

提高焊膏印刷质量的工艺改进

焊膏印刷作为SMT工艺的第一步，其质量好坏对SMT工艺有着重要影响。文章通过对焊膏成分、特性的分析，讨论了印刷中各种工艺参数的正确选择；对焊膏印刷中容易出现的质量问题进行了详细分析，指出了产生问题的原因，提出了改进措施。     

无机高分子絮凝剂聚硫酸铁合成条件的研究

实验研究了以工业硫酸亚铁及废硫酸为原料,分别采用NaClo_3、KClO_3、H_2O_2及(o_2+NaNO_2)为氧化剂成聚硫酸铁的条件。在以(O_2+NaNO_2)为氧化剂的合成过程中,发现添加微量助催化剂(型号为HG-1、HG-2和HG-3),对提高合成速度及反应过程的稳定性具有重大作用。     

β21s高强度钛合金的铣削试验研究

针对一种新型的难加工钛合金材料β21s,进行了刀具磨损试验和铣削力的测量试验,对材料的切削加工性进行评价,并且给出优选结果,为实际生产提供参考。     

ICP-AES法测定硅铝钡合金中的钡

介绍ICP—AES法测定硅铝钡中的钡的分析方法，用氢氟酸一硝酸一高氯酸混合酸溶解试样，用钡的233．527nm谱线测定钡．该方法简便快速，精密度好，准确度高，加标试验回收率为99％～100％，相对标准偏差为0．25％～0．56％．     

燃煤MHD发电Cr25Al5电极材料的腐蚀行为研究

采用Ｃｒ＿（２５）Ａｌ＿５合金进行煤渣／种子条件下静态腐蚀试验（温度１３７３－１５７３ｋ，时间５０－１５０ｈｒ），试验后得出三种温度下腐蚀重量变化与腐蚀时间的关系，并借助金相显微镜、扫描电镜和俄歇分析进行有关形貌及成份分析，试验表明，温度是材料腐蚀的主要因素，在１４７３ｋ条件下材料的抗蚀性最好，Ａｌ、Ｓｉ元素在腐蚀过渡层中富集，Ｃｒ元素变化不大，但有从基体向外扩散的趋势。由此，这一材料若能进一步改进，可望在控制壁面温度的半热壁型通道中进行试验研究。     

大型复杂高精度波导钎焊设备的研制：简介ZHS—132型真空钎焊炉

应军事电子装备，特别是军用雷达预研和生产的急需，电子工业部第二研究所近期研制的成功大型、复杂、高精度波导钎焊设备ＺＨＳ－１３２型真空钎焊炉。文中主要介绍了该设备的开发背景和对波导钎焊工艺的影响，该设备的设计构思、结构和技术特征，使用功能和效果，以及推广应用前景。     

K418B合金细晶铸造整体涡轮真空热处理工艺研究

通过力学性能评估和金相组织观察，研究五种热处理制度，两个周期的试验结果，确定了Ｋ４１８Ｂ合金细晶铸造整体涡轮的真空热处理工艺。