Mg-6Al-1Nd-1.5Gd合金的高温蠕变机制

采用高温蠕变装置,研究了Mg-6Al-1Nd-1.5Gd合金在150、175、200℃以及50、70、90 MPa条件下的高温压缩蠕变行为,分析合金在高温蠕变过程中的蠕变机制。结果表明,Mg-6Al-1Nd-1.5Gd合金的平均应力指数及蠕变激活能分别为4.64和73.87kJ/mol,其主要蠕变机制是由位错攀移和晶界扩散共同作用,合金的蠕变本构方程为:ε=1.877×10-8σ4.641exp[-73 865/(RT)];合金在高温蠕变过程中,微观组织中的位错密度逐渐增大,出现位错缠结及位错堆积,合金蠕变后的晶粒变得粗大,金属间化合物Al3Nd和Al3Gd在晶界上出现偏聚。     

基于ASP的中小企业联盟模式研究

网络技术正在对企业发生深刻的影响，如何应对和主动适应是中小企业要考虑的问题。分析了中小企业联盟的内涵特征，根据我国中小企业网络、信息资源现状建立了基于ASP的运营模式，构建了中小企业联盟的知识共享机制以及实施模式。     

(TiB_2+Al_3Ti)/ZL101原位复合材料的强化机理

采用透射电镜对(TiB2+Al3Ti)/ZL101原位复合材料中增强相组织、结构和分布进行了研究,测试了(TiB2+Al3Ti)/ZL101原位复合材料的力学性能。结果表明,原位复合材料经热处理后,其抗拉强度、硬度及伸长率都比ZL101基体材料高,分别提高了23.3%、23.5%、14.6%;增强相TiB2和Al3Ti颗粒均匀分布于-αAl基体中,对基体具有显著的晶粒细化效果;(TiB2+Al3Ti)/ZL101原位复合材料主要强化机制为细晶强化、固溶强化、弥散强化和位错强化。     

焊机电源的噪声干扰源分析及抑制措施(二)

较详细地分析了焊机电源产生干扰的内部和外部原因，通过对干扰的3种传导方式分析．提出了抑制干扰源具体措施和应注意的问题。     

高精度铝带材纵剪机

介绍了高精度铝带材纵剪机的类型及最新技术，并对影响剪切质量的关键因素、张力控制形式等进行了综合分析。     

Microstructures and evolution mechanism of highly undercooled Ni-Pb hypermonotectic alloy

The microstructures and evolution mechanism of the undercooled Ni-20%Pb(molar fraction) alloy were investigated systematically by high undercooling solidification technique. The experiment results indicate that the morphology of α-Ni phase and the distribution of Pb element in undercooled Ni-20% Pb alloys change with the in-crease of undercooling. The main evolution mechanisms of α-Ni are dendrite remelting and recrystallization. Pb phase in the microstructure of Ni-20% Pb hypermonotectic alloy originates from L2 phase separated from the parent melt during the cooling process through immiscible gap and L2 phase formed at the temperature of monotectic trans-formation. The solubility of Ph element in α-Ni phase under high undercooling condition is up to 5.83% which is ob-viously higher than that under equilibrium solidification condition. The real reason that causes the solubility difference is distinct solute trapping.     

Anti-oxidation mechanism of SiC-B4C-C composites

Mixture of green petroleum coke, B4 C and SiC together with short carbon fiber were employed as starting materials, the mixture was press formed without any binder after grinding, dense and homogeneous binderless SiC-B4 C-C（carbon/ceramic） composites were then obtained after sintering. Composites thus prepared possess excellent anti-oxidation property, that is, mass loss less than IG within the temperature range from 900 to 1 100 ℃ for 10 h. Anti-oxidation mechanism was also discussed from the viewpoint of thermodynamics, excellent anti-oxidation property of materials thus prepared can be discribed to 1） solid SiO2 formed from SiC, which restrains the filtering of oxygen and simultaneously, its volume expansion brought about by the reaction takes roles both walling up the original pores and making the material more compact; 2） liquid B2O3 from the reaction of B4C not only makes the combination with C, B4 C and SiC tighter through forming solid solution, but also effect of reaction SiC（s）＋2CO（g） =SiO2 （s）＋3C（s） is an expansive process, which improves the microstructure of the material.     

限幅绝缘盖板注塑模设计

通过对限幅绝缘盖板的工艺分析,确定了开放型腔、滑块脱模的模具结构.此模具构思巧妙,结构简单,不但成功地解决了塑件成型、侧孔贯通、顺利脱模的问题,而且大大降低了模具成本,缩短了研制周期.     

多孔烧结材料锻造镦粗成形致密的特性研究

粉末锻造是一种新型高性能的精密塑性成形技术，但其成形时的特殊性导致目前缺乏完善的、普遍适应的粉末锻造成形理论。通过对还原铁粉烧结多孔体预成形坯锻造镦粗成形致密实验，研究了不同初始相对密度、不同高径比、不同摩擦条件对预成形坯锻造镦粗成形、致密的影响规律。得到了粉末锻造镦粗的断裂极限准则，绘制出了断裂极限应变迹线，并着重分析了初始相对密度、高径比和摩擦因子对镦粗断裂极限的影响，确定了镦粗成形极限工艺参数曲线。实验研究结果为粉末锻造预成形坯与模具的设计、工艺参数的优化奠定了理论基础，并提供了有价值的实验数据。