Rheological behavior of continuous roll casting process of aluminum alloy

The rheological behavior of aluminum alloy and its influencing factors in physical simulation of continuous roll casting process were studied by using a Gleeble-1500 thermal-mechanical simulation tester with a set of special clamp system. The relationships between the flow stress and the strain rate in the deformation process of simulating roll casting experiment were obtained. The results show that four different characteristic stages exist in the temperature range of the whole rheological process. The first occurs when the temperature is higher than 600℃, which belongs to the creep deformation stage; the second occurs when the temperature lies in the range of 500 - 600℃, and it can be regarded as the high temperature and low stress level deformation stage; the third occurs when the temperature decreases to the range of 300 - 500℃, it is considered to be the middle stress level deformation stage; the last occurs when the temperature is less than 300℃ and the strain rate is less than 1.00 s^-1 , it belongs to middle stress level deformation stage. But when the strain rate is larger than 1.00 s^-1, it belongs to the high stress level deformation stage. And the relative constitutive models suitable for the four different stages of continuous roll casting process were established through multivariate linear regression analysis of the experimental data.     

Microstructures of spinodal phases in Cu-15Ni-8Sn alloy

The microstructures of spinodal phases in Cu-15Ni-8Sn alloy were studied by TEM. It was found that when the alloy is completely in a as-quenched state, spinodal decomposition is quick. Ordering appears after spinodal decomposition. The ordered phase with DO22 structure has three variants obtained from coarsening spinodal structure. The reason of ordering appeared after spinodal decomposition is that the content of solute atoms needed by ordering is higher than the average, which can be reached by the composition fluctuation of spinodal decomposition. It was speculated that the morphology of the ordered phase is needle-like.     

The Effects of Aging Precipitation on the Recrystallization of CuNiSiCr Alloy

The interaction between precipitation and recrystallization and its effect on the properties of the Cu-Ni-Si-Cr alloy during aging were discussed. The results show that the deformation results in much more dispersed precipitation of the phases. The precipitations have accelerating or retarding effects on the recrys allization. On the formation and growth of recrystallization, the precipitated phases are coarsed or dissolved in front of grain boundaries following a re-precipitation in the recrystallization area.     

液位传感器用磁致伸缩FeCo合金特性研究

研究了加工工艺和热处理工艺对Fe63Co合金饱和磁致伸缩系数(sλ)的影响。饱和磁致伸缩系数(sλ)最好为6.75×10-5。试验表明该合金的饱和磁致伸缩系数对热处理工艺不敏感。     

Al-Ti纤维增强Mg合金复合材料的制备及其微观组织

本文采用粉末冶金工艺制备出了一种新的Al-Ti纤维增强Mg合金复合材料,经光学显微镜、扫描电子显微镜和X射线衍射分析,表明Al-Ti纤维在Mg合金基体中分布均匀,制备过程中没有被损伤.纤维/基体界面上有不连续的颗粒状Mg17Al12析出,此析出相直径小于1.5μm,且数量很少.     

钛板圆孔翻边成形极限与形状非轴对称化研究

为确定钛板圆孔翻边成形性能,揭示各向异性对制件形状和尺寸精度的影响,在室温和600℃用TC1MS1.5 mm钛合金坯料分别进行了圆孔翻边成形试验.结果表明:与室温冷翻边相比,热翻边可有效提高成形极限、消除冷翻边制件形状翘曲以及唇口部位椭圆化现象,在唇口边沿完好与破裂状态之间存在集中颈缩形式,而冷翻边则在底孔尺寸小于极限值时会直接发生破裂;冷、热圆孔翻边变形程度越大,则形状非轴对称化程度越严重.     

镁合金表面覆盖层形成方法及相关国家标准

镁合金具有优异的比强度,但耐蚀性较差,很少在铸态下直接使用,需要进行表面处理以形成防护性覆盖层.本文对现有的镁合金表面覆盖层形成方法,如电化学镀、化学转化、阳极氧化、气相沉积、激光表面改性和有机涂层等,进行了评述.国家标准对相关技术等具有极强的指导意义,而目前系统介绍有关我国国家标准中涉及表面处理方面的资料很少,所以本文也针对目前国家标准中表面处理工艺、检测方法等进行简单的介绍.     

钛及钛合金仿生表面改性研究进展

钛及钛合金具有较好的生物相容性及优良的机械性能，在临床上得到了越来越广泛的应用。表面生物活性化能够进一步改善其表面性能，提高表面生物活性。本文对钛及其合金的仿生表面改性进行了综述，具体介绍了化学法、促形核剂法、自组装单分子法的活化机理，并对仿生表面改性的发展方向进行了探讨。     

Partial Remelting of Thixotropic Magnesium-Rare Earth Alloy from Near Non- Equilibrium- Liquidus Casting

After the investigation on partial remelting of thixotropic magnesium serial alloys （ZK60） by near non-equilibrium liquidus casting （NNLC）, the primary solid grains of ZK60-2Ca alloy spheroidized notably during partial remelting processing, however, coarsening and polygonization as occurred holding time prolonged. The refining and globularity of the thixotropic alloys are promoted after further alloyed by Y, RE, Nd and/or Ag, and the results vary with those addition. The remelting structure of ZK60-2Ca-1Y alloy is finer than its base alloy. And the effect of RE, especially Ag, on the refinement of microstrueture is notable, but Nd does nothing on it. There is little impact of remelting temperature fluctuation on partial remelted microstrueture as holding time in general. On the contrary, it is more sensitive at longer holding time. The quality thixotropic silver-contained alloy can be achieved by remelted partially at 600℃ for 10 min.     

GH4169合金的X射线荧光光谱分析

采用x射线荧光光谱仪测定GH4169合金中的锰、硅、镍、铬、钼、铝、钛、铌。研究了测量条件及基体 吸收—增强效应的校正。还时测量精度进行了研究,各元素的相对标准偏差分别为0．0466％～O．6777％。与 化学分析结果对照结果良好。