化工用Monel-400容器的焊接裂纹成因及优化工艺

对蒙乃尔合金400(Monel-400)材料焊接裂纹及其成因进行了分析,通过焊接试验研究,摸索和总结出了化工用蒙乃尔合金容器的焊接工艺,制定了相应的焊接工艺评定及专项技术措施,为现场优化施焊蒙乃尔合金容器及高返修合格率积累了一定经验,对类似设备的焊接制造亦有积极的指导作用。     

锆基金属玻璃中离子减薄诱导的微结构变化

用电化学双喷、凹坑法和离子减薄制备了4组Zr52.5Cu17.9Ni14.6Al10Ti5金属玻璃的透射电子显微镜样品。透射电镜观测表明,电子透明区域的微结构随采用的离子减薄条件变化敏感。通过对比选区电子衍射花样和相同成分样品等温退火的X衍射花样发现,在一些严重依赖于离子减薄制备的电镜样品中存在显著的加热效应,导致在离子减薄区域形成了不同的有序结构。在那些特意使用长时间减薄的样品中,可达到约780 K的局域峰值温度,远远超过了该成分的玻璃转变温度。这个结果表明,在用离子减薄获得非晶合金的电镜样品时,必须注意减薄过程所诱导的潜在的微结构变化,以避免得到错误的判断     

Fe60.5-xPt39.5Ndx(x≤1.5)合金相转变和居里温度研究

采用X射线衍射,差热分析和居里温度测量等方法研究Fe60.5-x Pt39.5Ndx合金的相转变、居里温度和有序度。结果表明：Nd的添加有利于稳定FCC相结构;随着Nd含量x的增加,Fe60.5-xPt39.5Ndx合金的有序度及有序FCT相的居里温度都逐渐减小     

Microstructure and properties of high silicon aluminum alloy with 2% Fe prepared by rheo-casting

The morphology changes of both Fe-containing intermetallic compounds and the primary Si phase of Al-20Si-2Fe- 2Cu-0.4Mg-1.0Ni-0.5Mn (mass fraction, %) alloy produced by semi-solid rheo-diecasting were studied. The semi-solid slurry of high silicon aluminum alloy was prepared by direct ultrasonic vibration (DUV) which was imposed on the alloy near the liquidus temperature for about 2 min. Then, standard test samples of 6.4 mm in diameter were formed by semi-solid rheo-diecasting. The results show that the DUV treatment suppresses the formation of needle-like β-Al₅(Fe, Mn)Si phase, and the Fe-containing intermetallic compounds exist in the form of fine Al₄(Fe, Mn)Si₂ particles. Additionally, the primary Si grows up as fine and round particles with uniform distribution in a(Al) matrix of this alloy under DUV treatment. The tensile strengths of the samples at the room temperature and 573 K are 230 MPa and 145 MPa, respectively. The coefficient of thermal expansion (CTE) between 25 °C and 300 °C is 16.052 8×10^?6 °C^?1, and the wear rate is 1.55%. The hardness of this alloy with 2% Fe reaches HB146.3. It is discovered that modified morphology and uniform distribution of the Fe-containing intermetallic compounds and the primary Si phase are the main reasons for reducing the CTE and increasing the wear resistance of this alloy.     

基于神经网络泛函数的摩擦学系统转化模型研究

建立了摩擦学特性影响规律的径向基神经网络模型，可以较准确地计算和预测不同摩擦学系统条件下摩擦系数与各影响参数之间的关系；进一步基于神经网络建立了不同系统之间的泛函数关系，基本解决了摩擦学系统的条件转化，为摩擦学设计、程序化计算和分析提供了一种方便有效的工具。     

316不锈钢粉末直接激光烧结的球化效应

采用直接金属激光烧结的方法,对316不锈钢粉末进行了一系列激光烧结实验。实验发现,由于液相粘度较高、表面张力大以及熔体材料不浸润固相颗粒和基板等因素的影响,导致烧结过程中出现球化现象。球化的出现,一方面导致形成球形的液滴表面和不连续的烧结线,妨碍下一粉末层的铺放,不利于烧结的顺利进行,严重时还将会导致无法烧结成形;另一方面也使得烧结层留有大量孔隙,强度很低,成形质量不高。分析了316不锈钢粉末球化效应产生的原因,讨论了工艺参数对316不锈钢金属粉末烧结成形的影响。     

基于Pro/E前处理的有限元分析在机械工程中的应用

文中利用Pro/E软件进行前处理,再导入到ANSYS软件中对减速器的低速轴进行有限元分析,并说明了这种方法如何在整个机械行业中高效应用.     

The Structure and Mechanical Properties of Cr4Mo4V Steel Treated by PIII Carbonitriding

The composition and structure of PIII(plasma immersion ion implantation)carbonitrided Cr4Mo4V steel were analyzed using X-ray photoelectron spectroscopy(XPS),X-ray diffraction(XRD),optical microscopy(OM)and SEM.The results indicate that the nitride and carbide are dispersion phase precipitation and except formation of compound other implantation atoms dissolve into martensite matrix.The total concentration of carbon and nitrogen is about 30 at%near the surface,and still keeps at about 20 at%even at the depth of 8μm.The effect of treatment temperature,implantation time and ratio of N2 to CH4 on the hardness and wear resistance of carbonitrided layer are investigated.It is found that the hardness of Cr4Mo4V steel increases after treatment.The highest hardness of samples is 22.3 GPa,which is about 1.8 times than initial steel.The dry-wear resistance of the samples is also improved after treatment,and the sample with higher hardness shows the better wear resistance.     

AZ31镁合金薄壁管分流挤压速度影响规律仿真研究

基于DEFORM-3D平台,以军用战地发射塔天线用AZ31镁合金薄壁管分流挤压工艺过程为研究对象,研究建立了精确、高效的AZ31镁合金薄壁管分流挤压有限元模型。模拟研究揭示了挤压速度对挤压力、焊合压力及模口坯料金属峰值温度的影响规律。基于所得规律,综合考虑挤压力、焊合质量及挤出管材表面质量要求,获得了该规格AZ31镁合金薄壁管在2000t挤压机上的合理挤压速度范围为3.5~7mm/s。     

Study on superprism effect in the multilayer optical thin film stack

1Introduction Superprismeffectisaspecialphenomenon existinginphotoniccrystals(PCs)[12].Nowa days,manyresearchesdemonstratethatPCs possessanomalousdispersionandanisotropy propertiesnearthebandgap,leadPCsachieve hugedispersion[34].For1Dmultilayerstacks,whichownpeculiarproperties,canactasPCs,moreandmorepeoplechoosethisstructureto investigatesuperprismeffect[56].Wehaveused thesimpleststacks periodichighreflectance coatingsarrangedbyonly20layerstoachieve22μmofspatialdispersionbefore.Weselected…